Home-Grown Housing. A renewable resource to the UK housing crisis - Rebecca Sawcer by Cambridge Design Research Studio

Home-Grown Housing: A SUSTAINABLE RESPONSE TO THE UK HOUSING CRISIS

REBECCA SAWCER Jesus College University of Cambridge Design Thesis - May 2016 Word Count: 14,955 A Design Thesis submitted in partial fulfilment of the requirements for the MPhil Examination in Architecture & Urban Design (2014-2016)

‘The best friend of man is the tree. When we use the tree respectfully and economically, we have one of the greatest resources on the earth.’ FRANK LLOYD WRIGHT

ABSTRACT This thesis argues that any attempt to stem the UK’s housing deficit through an approach that does not thwart sustainability efforts requires consideration of both the materials chosen and their methods of procurement. As a response, it explores the positive repercussions that would ensue from a strategy based on afforestation of the Metropolitan Greenbelt and concludes that reestablishing such a commercial space for forestry, and establishing this as a ‘lung’ for the city, would provide a holistically sustainable resource for the provision of housing. It is argued that we must not only encourage, or enforce, the use of timber as a responsible and sustainable construction method, but also allow its widespread use to develop a new residential prototype that can begin to improve Britain’s attitude towards and experience of urban living. These solutions should stem from the naturally inherent advantages of this versatile and robust material, especially in its engineered form, and subsequently, ensure engineered timber design principles become synonymous with an improved residential typology.

ACKNOWLEDGEMENTS Firstly, I would like to thank Ingrid Schroder, Alex Warnock-Smith and Aram Mooradian, the MAUD course tutors, for their guidance and critique throughout my design research project. My sincere appreciation goes to everyone at Waugh Thistleton Architects for their support, knowledge and contagious obsession for all things CLT, both during my fieldwork period spent at their practice, and individually to the multiple members of staff who gave up their time to speak to me about their experiences and insights. I would like to thank David Leviatin and Mike Keogh for the time they devoted to teaching us their traditional timber craft first hand. Thanks also to the many professionals and academics who have offered up their time to discuss my research, both those with whom I have collaborated on projects at Waugh Thistleton and those with whom I have spoken independently; a full list of references can be found in the Bibliography. Much appreciation goes to Nicholas Ray, of Jesus College Cambridge, who has been a source of great help and support with my academic writing for this thesis. Lastly, but by no means least, I would like to thank my supervisor Simon Smith, of Smith and Wallwork, for his continued commitment to my research aims and for his time, assistance and support with my academic writing and design work; his vast knowledge within my areas of interest has been invaluable.

This dissertation is the result of my own work and includes nothing which is the outcome of work done in collaboration except where specifically indicated in the text. 5

CONTENTS Abstract

Acknowledgements

Contents

Introduction

Our Housing Predicament Housing Demand

Current Deficit and Perception

Regulations and Marketing

The Sustainability Imperative Construction Impact

The Original Building Material

Twenty-First-Century Timber Modern Timber

Prefabrication

Industry Perceptions

Changing the Pattern Home-Grown Timber

Timber First Policy

A New Architecture Advantage from Adversity

Designing in Timber

A New Aesthetic

Conclusions

List of Figures

Bibliography

91 7

INTRODUCTION The continued failure to provide sufficient housing to meet the needs of the UK’s burgeoning population has inevitably led to the deteriorating standards and escalating prices that are now so evident throughout our cities. This crisis demands a radical change to the strategies employed in the mass-provision of urban housing. To provide a sustainable future, not only the quantity of housing provided but also the methodology by which it is produced must be critically considered. The construction industry’s preoccupation with concrete and steel is so fundamentally at odds with sustainability that it is essential to consider alternative structural solutions for mid-rise urban developments. Subsequently, it seems viable to propose ‘home-grown’ engineered timber, in particular, crosslaminated timber (CLT). This system has the ability to lead to greater speed and efficiency of construction, its prefabricated nature offering the potential for manufacture to bridge the current deficit in production capacity within the industry. Simultaneously this new ‘home-grown’ material has the potential to create dwellings with a more generous flexible provision of space, transforming the ‘typical’ response to a CLT residential block. This design research aims to address the following questions: Firstly, how can the development of a new infrastructural system to grow and manufacture cross-laminated timber provide London with a genuinely sustainable system for housing production, and secondly; how can we use this radical change in primary construction material to innovate within the quality and aspiration of urban housing in the UK? This thesis will consider the reasons behind, and methods to address, the underutilisation of timber within UK construction. By exploring the origins of the UK-wide aversion to what is an otherwise global industry, it aims to identify the rationale underlying prevailing pessimistic attitudes. It will discuss the social, political, and economic factors that would affect a design proposal to re-forest the greenbelt and construct CLT factories within this zone. I advocate an approach that, with appropriate planning, could capitalise on the UK’s existing rail infrastructure to transport ‘home-grown’ CLT into the capital and mitigate our current reliance on imports. Such initiatives would provide architects and design teams with a strong foundation on which to persuade and incentivise their clients to invest in the inherent qualities of engineered timber as their primary structural solution. It is argued, that encouragement is required for the adoption of ever-improving prefabrication technologies and; that the necessary infrastructure is established to allow the production and use of CLT to become a truly sustainable self-sufficient construction system for the UK.

Home-Grown Housing

This proposed response to the UK housing crisis mitigates the seemingly inevitable, environmental impact inherent in such a huge house-building endeavour. It includes the means to overcome the negative perceptions surrounding timber construction and prefabrication in the UK; and specifies the infrastructural network needed to support the production of â&#x20AC;&#x2DC;home-grownâ&#x20AC;&#x2122;, engineered timber as a principle structural material. During the research period preceding the composition of this thesis, an extensive and varied exposure to the existing industry was gained to understand the broad spectrum of relevant issues. The design research undertaken has attempted to identify, understand, and evaluate the means that might be employed to shift public and professional attitudes towards timber as a building material and prefabrication within the housing market. Through literary review, historical insights were gained into the origins of current perception, together with a theoretical understanding of how these inappropriately negative views have been reinforced and maintained over time. Furthermore, hands-on experience of both traditional timber craft and timber architectural practice, alongside a research trip to an Austrian CLT factory, provided an in-depth and holistic overview of the issues and potential of timber construction, along with the opportunities for promoting and reinvigorating this vital industry. Through interviews with leading professionals in the varied fields of this currently niche method of construction, key areas to be addressed were defined. Dialogue with the likes of Peter Wilson, who leads the team investigating Scottish CLT, enabled a first-hand account of the barriers that need to be overcome. The knowledge and insight gained through this research have enabled the development of designs for CLT urban residential schemes using an architectural language that stems from the advantages of the material, whilst recognising and mitigating its drawbacks. Avoiding the tendency to mimic standard concrete and steel solutions, the explorations instead aim to give designs an identifiable aesthetic that acknowledges and advertises their CLT structure; the resulting increased awareness having the potential to increase demand for this material. Through these designs, building in CLT can be shown to improve the quality of housing by enabling the creation of highdensity dwellings that have the flexibility and quality of space needed for modern changing families. In this context, the housing crisis can be seen as an emblematic opportunity to develop a new sustainable prototype to improve both the quality and production of urban housing.

Introduction

OUR HOUSING PREDICAMENT

New homes built annually, London

50000

49000 homes annually, LIP target

45000 40000 35000 30000 25000 20000 15000 10000 5000 0

1961-70

1971-80

1981-90

1991-00

2001-10

2011-20

2021-30

2031-40

2041-50

New homes built annually, London

fig. 1.0: numbers of homes built annually in london, averaged for each decade; with the current decade estimated from data up to 2014. Compared to the quantity pledged by the Government in the LIP. drawn by author, data: GLA, 2015.

HOUSING DEMAND Throughout the last two centuries, housing in Britain has repeatedly become an issue of great concern, not only for politicians but also the general public. Today Britain again faces an extreme housing crisis; the vast housing deficit, particularly prevalent in cities, has led to the London Infrastructure Plan identifying the need for 1.5 million new homes by 2050 (Skinner et al., 2014/15). The current political emphasis lies most definitely upon rapidly building many new dwellings, but with little discussion of their character or their impact on sustainability. In the recent ‘Case for Space’ document, produced by the RIBA, Harry Rich states most eloquently: ‘In a rush to build quickly and cheaply we risk storing up unnecessary problems for the future. We do not believe that there is any need to see a contradiction between building or refurbishing enough homes and making sure that they are of the highest quality’ (Roberts-Hughes, 2011, p.3). British architects once again seek to devise new ways of solving a housing crisis. In our current attempt to increase the housing stock with homes that people will come to appreciate, it is clear that we can learn much from the difficulties and successes of earlier generations. The declining supply of affordable homes has become an increasingly significant issue over recent years, as illustrated by the substantial rise in private renting that has emerged since the 1990s. The average age of firsttime buyers is increasing as even well-paid young professionals struggle to afford a mortgage. In the year preceding March 2016, UK house prices rose 9%, with the highest increases in England, driven primarily by those of the South East, particularly London where prices increased by 13% (ONS, 2016). Estimates suggest that the UK needs to build around 250,000-300,000 new homes each year to satisfy demand, significantly more than our current annual production, which rarely exceeds 100,000 per annum (Oxley, 2016). Fig. 1.0 clearly illustrates this substantial shortfall through data and aims for London. It is evident from these statistics that our current construction methods are completely unable to meet the required output, and that solving this crisis in production is a national priority. It is argued throughout this thesis that to produce the quantity of housing required a fundamental shift towards an alternative method of production is needed, to overcome this deficit through the use of prefabrication technology.

‘tower’

Occupants to move back into tower once children leave home.

‘maisonettes’ Couples to move into maisonettes once they have children.

fig. 1.1: diagram illustrating the proposed ‘user cycle’ for mixed developments. drawn by author.

CURRENT DEFICIT AND PERCEPTION The general populous are acutely aware of the housing shortage within the UK, one that is most evident in our cities, particularly London. This deficit is reflected by the massive rise in the number of families on housing waiting lists, which has increased by 65% since 1997 (Shelter, 2014). The commonly held belief that, within London, this problem is a result of limited space available to build on is erroneous, as there are in fact many areas not used to their full potential. The London Strategic Housing Land Availability Assessment (GLA, 2013) highlights London’s capacity for housing and its distribution across sites of varied condition ranging from substantial areas of brownfield to small infill sites. If the Government is to meet its targets of building 49,000 homes a year in the capital, all of these underused sites will need to be developed to their full potential. Whilst our cities already face the most urgent problems, the UN has predicted that 66% of the global population will be living in urban conditions by 2050; in Europe, this figure is predicted to be even higher at 73% (UN, 2014). For most of the population, the future clearly lies in the city with its environment of high-density living; that is at odds with the traditional British aspirational house with the picturesque qualities of a child’s drawing: a detached, traditional brick home with a pitched roof and garden. Furthermore, the British aversion to high-density living in the form of high-rise dwelling remains significant; for most people the social failures of towers blocks built in the second half of the twentieth century are still synonymous with a failing typology. Following extensive bomb damage during the Second World War, the reality of the housing density required essentially ruled out proposals along the lines of ‘garden cities’, particularly since the introduction of town planning finally began to stem suburban sprawl. In response, high-rise slabs based on continental European modernist principles became the main house building effort, as it was suggested that ‘high, widely spaced apartment blocks will liberate the necessary land surface’ (Sert, 1942, p247). The extensive introduction of tower blocks into the UK, largely by local authorities (together with lower density development in the form of ‘new towns’ of the 60’s and 70’s) was the closest the UK came to meeting housing deficit. In the post-war years around 2,700 tower blocks were built in London (Renaissance London, n.d.), helping to provide more homes than any other period. However, the mass production of the tower block typology showed no respect for, or reference to, any previous housing designs, successful or not, and attempted to sever all ties with the past. As a result, the population failed to identify with these homes. Efforts of efficiency unknowingly designed out elements of street life that had previously provided safety and community. Jane Jacobs highlighted the necessity for a neighbourhood concept in The Death and Life of Great American Cities (1961). She argued that communal areas with overlooking windows maintain a safe community, whereas, tower blocks encourage high levels of crime. High-rise blocks were originally proposed as part of a ‘Mixed Development’ concept said to be the solution to high-density housing. These developments relied upon the concept that different occupants would rotate their dwelling occupation between high-rise towers and maisonettes as their circumstances changed (fig. 1.1). However, this ‘User Cycle’ (Swenarton, 2012, p. 976) was quickly shown to be naïve, as those within the individual dwellings were reluctant to move, so families with children were forced to continue living in towers, further exacerbating the significance of the social issues that developed.

‘pavilion’

‘street’

‘courtyard’

fig. 1.2: diagram illustrating the massing findings of Leslie Martin and Lionel March; ‘pavilion’, ‘street’ and ‘courtyard’ forms providing equivalent floor area on the same site through different numbers of floors. drawn by author, data: Towers, 2005.

Our Housing Predicament

A common mistake throughout the population, and to some extent the profession, is that high-density housing is viewed as synonymous with and almost inseparable from these high-rise blocks. If higher density urban living is to be successful in the UK in the twenty-first-century, we must address this by illustrating that high-density homes can still provide generous, flexible and useable space. Research by Leslie Martin and Lionel March in 1972 analysed what they considered were three key urban forms; ‘pavilion’, ‘street’ and ‘patio’ (fig. 1.2). Their research illustrated that the same density could be provided on any given plot for development through different configurations of blocks which subsequently required different heights; essentially the same floor space could be provided in a mere three-storey perimeter block as a fifteen-storey tower set in ‘parkland’ (Towers, 2005). These findings led the way for similar studies and thereby the work of the Camden housing architects, the likes of Neave Brown, who rejected the modernist tower block for more low-rise organic proposals which were influenced greatly by their context and critical housing traditions. Almost all of the architects were alumni of the Architectural Association where at that time a new housing typology was being promoted; ‘where high-rise was unequivocally rejected in favour of low-rise, high-density urbanism’ (Swenarton, 2012, p. 976). Unlike in most modernist fixed plan housing, Brown’s designs incorporated the need for a house to be adaptable; he favoured largely open plan interiors with sliding doors for flexible living. This simple feature meant that cramped unusable spaces could be avoided despite the modest space allowance in council housing. In 1961, the Parker Morris Committee report ‘Homes for today & tomorrow’ had a strong influence on the mechanism for spatial designs within public sector housing, stating that ‘the important thing in the design of homes is to concentrate on satisfying the requirements of the families that are likely to live  in them’. This was a bold step for housing design, which at its worst had previously focused merely on meeting by-law regulations. These more thoughtful and nuanced approaches to high-density housing had a greater level of acceptance from the public and were enjoyed by the people who lived in them. A testament to their design, this continues to be the case today as they have been able to adapt to changes due to their built-in flexibility. It can be argued that this approach should be employed when considering future developments to meet the current demand, in a way that ensures the housing provided is not only widely accepted, but promotes a positive view of urban living in which people can easily envisage their current and future habits and routines.

Current Deficit and Perception

76m2

116m2

137m2

Netherlands

Denmark

fig. 1.3: Comparative areas of average new build dwellings for the UK, the Netherlands and Denmark. drawn by author, data: Roberts-Hughes, 2011.

REGULATIONS AND MARKETING Homes currently built in the UK are the smallest in western Europe, the average new British home being only 76m2 compared to 116m2 in the Netherlands; 52% larger, and 137m2 in Denmark; 80% larger (fig. 1.3) (Roberts-Hughes, 2011). This data is particularly poignant given that the Netherlands has a higher population density than the UK. The additional space provided in these countries could be the difference between these buildings’ inhabitants having the flexibility to adapt their dwellings as their needs change. In almost all circumstances the primary driving force for higher density housing in the UK lies in profit; whilst there are those who try to provide quality housing, most do not. The prevailing housing crisis has lowered the expectations of the population, desperate for anything they can afford. With increasing numbers of the population forced into the rental market, wealthy individuals and foreign investors are increasingly seeing property purely as an investment. Councils are giving up land to volume housebuilders in an attempt to upgrade social housing in great need of regeneration but at cost. The extent of ‘affordable’ housing provided to replace that which is demolished, is a frequently contested issue. Housing regulations were brought in as a mechanism to bring low-quality housing up to a level that allows basic comfort and room to live whilst easing issues of overcrowding. The drive to squeeze the maximum number of homes out of every plot to raise profit, drove the recent implementation of housing standards for London, in the form of the London Housing Design Guide. While this is a step forward, the recent analysis presented in the aforementioned ‘Case for Space’ document confirms homes outside London are consistently falling short of these minimum levels, while within London, the regulations are now viewed as more of a housing goal than a bottom line minimum. The volume housebuilding industry rarely strives to give more, subsequently repeatedly building to these standards that offer no flexibility and are yet to be established as sufficient. Significantly, homes in the UK are primarily marketed by their number of bedrooms rather than floor area, as is the case in most of Europe. Consequently, the information provided for different properties varies dramatically: some show plans, but few of these show furniture which would allow potential buyers to imagine what these spaces offer. Often fewer smaller rooms, with an overall smaller floor area, will be planned into housing designs to maximise the value achievable from a plot; increasingly important to developers whose profit margins have also become vulnerable due to dramatic increases in land price. If the floor area of each dwelling were listed, then potential buyers would have a better idea of what they were buying and the mechanism by which to sell less space for more money would be eliminated.

Our Housing Predicament

This tradition is seen as unchangeable, and the concept of sale based on the area of flexible, adaptable space seems to have been completely overlooked by the UK housing market, undoubtedly driven by the potential for increased revenue provided by the current marketing method. Building to the minimum ‘livable’ areas allows no freedom for adaptability: with the minimum space allowance and very rigid cellular design, there is essentially no potential for subdivision or reassigning spaces to accommodate the natural changes every family experiences. Clearly, we cannot assume that the fundamental deficiencies in previous attempts at high-density housing will spontaneously resolve themselves without some form of innovation and intervention. How to incentivise or, if necessary, enforce, a quality of accommodation which would make highdensity solutions an aspirational home type for the British population, is an immense task. It will necessarily require overcoming the past reputation of highrise housing. By provision of a generosity of space within each dwelling we can allow a longer term of residence, and thereby encourage the development of communities. Providing flats that would be considered as a home to the same extent traditionally associated with a detached or terraced house requires this flexibility, but these dwellings must also be fundamentally affordable. It is further argued throughout this text that ‘home-grown’ CLT driven housing solutions will enable the provision of larger flexible units, without compromise on overall build cost or densities, through efficiencies in the manufacture and optimisation of the structural solution.

Regulations and Marketing

THE SUSTAINABILITY IMPERATIVE

800

1990 Baseline

750

Kyoto Protocol

700 650 600

2009 Carbon Budget

Total Annual Emissions (millions tonnes CO2e)

550 500 450 400 350 300 250

Climate Change Act 2008

200 150 100 50 0 1990

2000

2010

2020

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Year

fig. 2.0: current UK emissions vs. set reduction targets. drawn by author, data: Department of Energy & Climate Change, 2013.

2040

2050

CONSTRUCTION IMPACT The construction and use of buildings currently account for around half of the UK’s carbon emissions (UKGBC, 2014b). Accordingly, it is clear that any efforts to expand the provision of housing using existing building methods are incompatible with the government pledge to cut carbon emissions by 80% before 2050 (fig. 2.0) (Climate Change Act of 2008). Without radical changes, the housing crisis and sustainability are mutually exclusive imperatives. This conflict demands a radical overhaul that must embrace alternative, more sustainable materials. The typical reaction of architects, planners, and local authorities, who propose steel and concrete solutions for medium and highrise developments, due to their familiarity, is no longer possible. These projects must now embrace alternative materials, such as CLT, as the need to reduce environmental impact is imperative. Modern building regulations were introduced in response to the Climate Change and Sustainable Energy Act of 2006, with the intention of reducing the operational impact of buildings. Whilst buildings since this introduction have been designed to be low energy; their actual performance has in some cases not met expectations. Nevertheless, as a trend, operational energy has been considerably reduced across the board. This impact has been the main focus of UK legislation, with increased insulation and improved airtightness easily integrated into existing frameworks (UKGBC, 2014a). As a typical building project moves closer towards the ‘passive house’ model, its whole life-cycle impact decreases, but the significance of its embodied carbon escalates, making this the next issue to address. In 1990, the world’s first sustainability assessment for buildings was introduced; BREEAM ratings aimed to provide recognition of where sustainability efforts went above requirements (BRE, 2015). However, the method for determining the rating achieved is unfortunately fundamentally flawed; the ‘tick box’ system tends to undermine individual consideration of how to design a truly sustainable scheme. Despite up to 50% of a building’s whole life carbon footprint now resulting from the construction materials used, this variable continues to be unaddressed with embodied carbon assessment excluded from regulations and BREEAM ratings (CTI, 2016). Awareness of this huge issue is minimal, and currently, there are no simple means by which to incentivise reductions within this aspect of construction. As a result, the industry remains dominated by concrete, as illustrated by the production volume of its carbon-intensive constituent, cement, which in 2006 stood at 2.55 billion tonnes, a figure that is increasing year on year. With the manufacture of a tonne of cement producing a tonne of CO2, its production is undoubtedly one of the most polluting construction processes (Rubenstein, 2012). Such energy intensive manufacture is clearly unjustifiable for constructions where these materials are structurally unnecessary. A significant number of alternate solutions are becoming available, including CLT (fig. 2.1), particularly for mid to high-rise residential blocks where the stresses and strains are not substantial enough to require a material such as concrete or steel.

Cradle to Gate Embodied Carbon Dioxide Equivalent (kg CO2e/kg)

2.5

1.5

0.5 CLT 0 Concrete

Steel

Construction Material

- 0.5

-1

Resulting Embodied - Processing

- 1.5

-2

Sequestered

fig. 2.1: comparative impact of concrete, steel and CLT. drawn by author, data: ASBP, 2013 and Hammond and Jones, 2008.

The Sustainability Imperative

This issue is exacerbated by the â&#x20AC;&#x2DC;substitution of more material for less labourâ&#x20AC;&#x2122; (Allwood, Ashby, Gutowski and Worrell, 2013) paradigm that has become a common means to reduce engineering fees and provide redundancy within a structure as a form of assurance in the design. Research has illustrated that less than 40% of the concrete within a typical four-storey concrete frame performs structurally (Wise, 2010). Enforcing the percentage of functioning material within building regulations is difficult, as material optimisation is not cost effective while materials are cheap and labour, combined with more individual forms, is expensive. City living is inherently more sustainable in many ways: reduced transportation, more walking and cycling, fewer roads and less heating in winter. There are further economies of density and scale. However, with current high-density housing solutions almost entirely restricted to concrete and steel, it is through the construction, rather than the habitation, of urban housing that the higher carbon impact can be seen. In rural areas, where timber framing and traditional vernacular methods are still used to some degree, this issue is less severe. If we are unable to provide a sustainable method of construction for creating urban environments, then any economy of density will be considerably undermined. By considering a new material approach, we can introduce the concept of maximum material efficiency from the outset allowing designs to stem from its properties; thus, material efficiency will become synonymous with this new form of construction, using a material whose growth can begin to control the embodied carbon issue. Our industrial capabilities have progressed since the introduction of steel and concrete, and once again we must adapt to modern advances that have allowed for the invention of technologies and new materials that can compete within urban construction. In this context, a change in the primary building material employed by the industry is one of the few ways to close the gap between the housing needs of the population and the sustainability requirements of the planet. Through this understanding, we can argue that integration of embodied carbon into BREAAM ratings and building regulations is essential and must be implemented; however, if introduced suddenly in a top-down manner we need to be aware that it is likely to be met with fierce opposition from the steel and concrete industries.

Construction Impact

fig. 2.2: Rewritten, pro-timber story, undoing the negative perspective of timber, perpetuated through fairytales such as the â&#x20AC;&#x2DC;Three-Little-Pigsâ&#x20AC;&#x2122;. artwork and photograph by author.

THE ORIGINAL BUILDING MATERIAL Timber can be considered the original building material, and is the only replenishable material whose production has a net positive impact on efforts to reduce our carbon footprint. It is undisputed that the growth of trees absorbs CO2 and humans are yet to find an industrial process as efficient as photosynthesis towards this aim. Up to a tonne of CO2 can be harvested from the environment and locked into a cubic metre of timber as it grows (CTI, 2016). In proposing a timber structural system, we can not only reduce the impacts of concrete manufacture but also begin a process of mitigating current atmospheric carbon levels, making this proposal a new sustainable housing typology that will actively decrease our carbon footprint. However, the vast networks used for importing and exporting timber internationally, significantly limits its genuine sustainability. As different countries produce different quantities of different types and qualities of timber, the transportation impact can be substantial, even for countries which grow significant volumes themselves. Consequently, it is logical for us to find methods of using the timber we can grow in the UK, as was traditionally the case. There are myriad reasons behind the UK’s aversion to timber which has allowed our forestry and timber industry to dwindle and lose significance while elsewhere in Europe and the world it remains integral and has developed modern applications. When looking to understand the rationale behind the current restricted scope in the UK, we are immediately confronted with the negative perception of timber, in both craft and construction, and the accompanying pessimistic attitude that has long been perpetuated in the UK. These negative associations seem like an almost unsurpassable barrier, so ingrained in our society’s psyche is the belief that houses should not be made of sticks or straw but only of brick, as every child is taught from an early age (fig. 2.2). ‘Traditionalists favour brick and block. In Britain, ‘bricks and mortar’ are regarded as a safe investment, while the 170-year-old technology of the timber frame is seen as dangerously experimental. It may be true that timber is more vulnerable in Britain’s damp climate, but the public’s willingness to believe scare stories is probably a bigger factor’ (Davies, 2005, p. 155). There is evidence that roughly 6,000 years ago, before any human intervention, 75% of the landmass of the British Isles was covered in woodland (Peterken, 1993). Our ground conditions vary across the island with patches, particularly in the South East of England, which cannot naturally yield dense forests. However, this previous level of forest coverage illustrates that our climate is more than capable of growing trees of sufficient quality for construction.

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

fig. 2.3: European percentage forest coverage by country. drawn by author, data: SCBD, n.d.

The Sustainability Imperative

Historically the arrival of the first ‘hunter-gathers’ saw the beginning of the extensive deforestation of Britain. Initially, it was very slight as communities created small clearings, using the surrounding common woodland to ‘gather wood, collect nuts, dig turf, pick berries, hunt or trap wild animals and birds’ (Whitlock, 1979, p.15). As the population increased, so did the clearings and our relationship to the forests changed. Agriculture largely took over from scavenging and woodland became viewed as purely a source of lumber; we lost our respect for and understanding of the intricate ecosystem within a forest. Forests were still highly prized with large volumes of high-quality timber essential for the naval forces, however, by the end of the nineteenth century, new materials and timber imports were introduced and quickly became viewed as sufficient, ending indigenous forestry efforts: ‘It has been shown that the command of the seas, assured in the early part of the nineteenth century, the change in materials introduced in the construction of ships, the increased facilities in transport and communication, the removal of the import duty on colonial and foreign timber, and the change in the kind of classes of timber used in construction etc., brought about the gradual decrease in the amounts of home grown timber used, and consequently in replanting, and resulted in the decline of British forestry as a commercial undertaking’ (Stebbing, 1919, p.176) During the First World War, for the first time, a shortage of home-grown timber became an issue due to the vast quantities required for trench building combined with the isolation of the UK as an island. As a result of these challenges, self-sufficiency was highlighted as a top-priority that ultimately led to the formation of the Forestry Commission in 1919, who were tasked with reforestation and afforestation. Still active today, their records illustrate that our coverage increased from 4% in 1871 to its current level of 13%, a substantial increase but still less than the European average of 34% (fig. 2.3) and far below the coverage we once had. Studies have illustrated that a significant portion (65%) of British forests are owned by individuals and bodies other than the Forestry Commission (Forestry Commission, 2003). This helps explain the limited increase in forest coverage along with our low levels of management and subsequent low yields. Studies have illustrated we manage only 32% compared to a European average of 56% (Forestry Commission, 2010), which can be largely attributed to our ignorance of its potential capital and environmental benefits. The timber we produce commercially within the UK is typically regarded as low quality; suitable for fencing, pallets, and packaging. As a result, imports almost entirely dominate construction (Moore, 2011). Only 1.2mt (million tonnes) of the 11mt of timber produced annually is used within construction as home-grown sawn softwood (Smith, 2013). Importing timber has high transportation impacts which are often overlooked due to the tendency to consider timber as a ‘clean and natural’ material.

The Original Building Material

fig. 2.4: commercial forest; thinning and transportation, Norway. photograph by author.

fig. 2.5: recreational forest, England. photograph by author.

The Sustainability Imperative

In addition to the widespread view of â&#x20AC;&#x2DC;home-grownâ&#x20AC;&#x2122; timber as low quality, there are also bureaucratic factors which limit its potential use in construction. The established buying and selling cycles account for all currently felled timber. This coupled with the extensive certification required for construction timber, this ensures that where architectural schemes propose the use of home-grown timber, such as those by the London-based firm Architype, it is opposed by barriers within the existing industry (Todd, 2014). Those forests not actively managed are largely used for conservation, shooting or other recreational past times. It is, therefore, difficult to incentivise these owners to initiate management as they do not see their forests as a source of income and enjoy their current uses (Lawrence et al., 2010). The general public considers forests and woodlands as primarily recreational features, having a romanticised, nostalgic view of these spaces, with the result that they are aversive to the felling of trees, and prefer not to see forests as commercial. Commercial and recreational forests look different; contain different species of trees in different forms. Forestry practice can make commercial forests look sparse towards the end of rotations (fig. 2.4), and although in general complete monocultures should be avoided as this can cause issues due to the imbalance of the diverse forest ecosystem, a commercial forest is likely to look more uniform and could be seen to be less picturesque. From a sustainability standpoint, it is well known that most species of trees reach a point at which they no longer sequester significant levels of carbon compared to trees in the most productive period of their lives. While it is vital to protect ancient woodland it is important to make the public aware that although trees act as a carbon store for the duration of their lives if we are to increase the volumes stored, we must plant new, young trees. Softwood requires a relatively short time for growth, channelling this timber into a product that will be preserved, continually adds to our carbon store, reducing existing atmospheric levels comparatively quickly. In short it is not sufficient to rely on existing trees. As one of the worldâ&#x20AC;&#x2122;s most significant importers of timber the UK surprisingly has less than half the per capita use of wood compared to Germany (FAO, 2011). In many central European countries, timber is essential to their way of life, both for traditional crafts and through investment in and development of modern advancements, including engineered timber for construction. Their established infrastructure, knowledge and educational systems have been adapted and developed over years. Our timber industry is comparatively stunted, and for us to compete at this level will require significant investment along with extensive education in all aspects of the timber industry. This lack of education and awareness of the forestry industry is illustrated within a body of research by Lantra. It showed that, within the land-based and environmental sector, 40% of employers (double the average across all other sectors) were unable to find employees with the required skills and similarly, a far higher percentage than average was said to be uninterested in doing this work (Lantra, 2014). The knowledge base and skills present in countries such as Austria and Germany must be reintroduced here, and it is essential for the future success of the industry that we provide appropriate education and apprenticeships as part of the investment.

The Original Building Material

TWENTY-FIRST-CENTURY TIMBER

Finger Jointing - 1 Edge Gluing - 2 Cross-lamination - 3 1 2

fig. 3.0: manufacturing process for cross-laminated timber. drawn by author.

MODERN TIMBER Cross Laminated Timber (CLT) is one of the few building materials which holds the potential to solve the housing crisis by sustainable means. Though there are definite advantages to this method of construction, several barriers prevent its generalised uptake. A concerted campaign to improve awareness of CLTâ&#x20AC;&#x2122;s advantages through policy changes and architectural design that stems from its properties will allow its success in facing the housebuilding task, where other solutions have failed or are set to undermine sustainability goals. By integrating a new logic for housing into the initial design process as synonymous with CLT designs, the housing produced can not only be executed as sustainable and profitable construction, but can ultimately produce dwellings which are aspirational for British homeowners. The term â&#x20AC;&#x2DC;engineered timberâ&#x20AC;&#x2122; includes a range of products from Glulam and CLT, through to laminated veneer lumber and brettstapel. Although these products vary in their individual characteristics, they all utilise small sections or lamella bonded together (fig. 3.0) to make an inherently stronger product, which can be manufactured into much larger elements than are generated in nature. These products have enhanced structural potential also substantially mitigating the fire and acoustic issues inherent in timber frames (Thompson, 2009). As a solid load bearing panel system, CLT requires high volumes of timber; typically, 2 to 3 times the volume used in a traditional frame (Smith and Wallwork, n.d.). This is advantageous from a sustainability perspective as it stores more carbon, however, to ensure we reduce volumes of concrete and steel used overall, we must use this material responsibly, getting the most from our available timber. Three to four skilled workers using only hand tools and a mobile crane can typically erect a CLT frame at a rate of at least one floor per week (Waugh, 2015). Furthermore, fixing into CLT, cutting missed openings and completing the work of follow-on trades is easier, faster and safer. The lower weight of CLT compared with concrete results in further cost savings since on average these frames only require one-third of the number of piles (Ogle, 2016). The lightweight nature of CLT also allows development of sites with limitations in ground works, for example, due to underground railway lines or sewers. Where ground loading is limited, a greater number of stories are possible in CLT than conventional construction, allowing higher densities to be achieved.

fig. 3.1

fig. 3.2

fig. 3.1: Woodberry Down under construction, fig. 3.2: Dalston Lane under construction (both Waugh Thistleton Architects) photographs by author.

Twenty-First-Century Timber

The advantageous thermal properties of timber lower the energy required for heating and enable rapid temperature regulation in CLT constructions. Furthermore, timbers natural ability to regulate moisture and humidity; together with its acoustic dampening and tactile surfaces provide a strong connection to nature and calming environments. Currently, these benefits are limited by the tendency to conceal timber, however, were it to be exposed this would begin to change the way people experience these homes, as is proposed in this design research. â&#x20AC;&#x2DC;Wood has the best thermal insulation of any mainstream construction material â&#x20AC;&#x201C; five times better than concrete, ten times better than brick and 350 times better than steel. Timber absorbs, saves and re-emits moisture making constructions from the material moisture regulatingâ&#x20AC;&#x2122; (Thompson, 2009, p.26). Timber is often seen as an adaptable material, making it a natural choice for housing. In the proposed schemes, the main structural CLT panels would not be moveable and would only be adaptable to a limited extent. However, the small changes most people make to their homes are likely to be possible, and further methods of adaptability will be included and explained in more detail in the sections to come. Although CLT has long been perceived as high cost, given that it has an inherent buildability with reduced construction times both for the CLT assembly itself and for preceding and follow on trades, the overall build cost is at least on par, and often favourable, to conventional construction (Waugh, 2015). This reduction in cost will allow the provision of generous, flexible units within developments without loss to profit.

Modern Timber

fig. 3.3

fig. 3.4

Ronan Point following gas explosion and progressive collapse. fig. 3.3: source: http://www.failedarchitecture.com/the-downfall-of-british-modernist-architecture/ fig. 3.4: source: http://www.bdonline.co.uk/precast-disaster/3087206.article

PREFABRICATION Despite the enormous potential of prefabrication, the approach has an extremely poor reputation in the UK, overcoming which is undoubtedly one of the greatest challenges facing any effort to expand the use of CLT in the housing industry. The historical roots of this misperception can be traced back to the effects of the last war during which bombing destroyed nearly half a million homes in the UK, tipping a pre-war shortage into a severe housing crisis. In response to this in October 1944, the Government allocated £150 million for the provision of temporary homes (Davies, 2005). These homes were to be small and of non-conventional construction and were marketed as an emergency response. Their labelling as ‘temporary’ allowed greater public acceptance, reassured conventional building workers that their skills would still be required for the ‘permanent’ housing solution and avoided any suggestion that the government was ‘treading on the toes’ of Local authorities. Unfortunately, despite the application of advances in technology the various models of prefabricated housing that were developed were frequently poorly constructed. As a result, despite initial popular enthusiasm, and contrary to the potential of prefabrication, these houses were ultimately disliked by the general public. Total production of these ‘prefabs’ eventually reached an impressive total of 156,623 (Davies, 2005). The reputation of prefabrication declined further when structural issues came to light following the purchase of PRC homes through Thatcher’s ‘Right to Buy’ legislation, whose structural problems cemented the view of prefabrication as being of low quality, and a poor investment when compared with traditional housing. Any remaining public confidence in high-rise blocks and prefabrication was all but obliterated as a result of the collapse of an entire corner of the newlycompleted concrete panel tower block, Ronan Point in May of 1968 (figs. 3.3 & 3.4). Four people were killed and many more injured; the resulting public enquiry found that a gas explosion had caused progressive collapse due to the unsound nature of the structure. Subsequently, stringent requirements to avoid this sort of failure within the structure were included in the design codes, but the stigmatism and negative perception of, particularly prefabricated, high-rise structures as being unsafe continues to this day. To eradicate this outdated negative connotation, we must not only explain that current day regulations ensure the structural and safety failures of the past could not replicate, but must also fully illustrate the real benefits of modern day prefabrication. ‘Today, the wooden house is produced by machines in factories, not by the craftsman in his shop. A traditional, highly-developed craft has evolved into a modern machine technology; new applications and new forms are being developed’ (Wachsmann, 1930/1995). The precise, clean aesthetic achievable via factory produced elements have given timber the opportunity to achieve the modern aesthetic described by Waschmann, a pioneer of prefabrication. The need for the UK construction industry to adopt modern methods to combat the current low-quality products and wasteful practices, as highlighted in the Latham report (1994) and reiterated further in the Egan report (1998), remains a key issue today. The architectural obsession with each building being a ‘one-off’ with the logic that any degree of replication undermines a building’s position within the field remains as an underlying opposition to ‘manufacture’.

fig. 3.6

fig. 3.5

fig. 3.7

fig. 3.8

fig. 3.5: Humdifier, fig. 3.6: Main warehouse, fig. 3.7: CNC Router, fig. 3.8: Surface finishing/sanding, KLH manufacturing centre, Katsch an der Mur, Austria. photographs by author.

Twenty-First-Century Timber

Despite standardised large-scale factory based production, many commonplace building materials, such as bricks and sawn lengths of timber, escape being considered as prefabricated. In principle, there is no reason why CLT could not also be considered in the same way if it were possible to distance the material from the vision of prefabricated housing which so famously failed in the past. The fact that the production of CLT panels is automated, subsequently benefitting from the ensuing advantages regarding efficiency, accuracy, and speed does not need to restrict the freedom to design with these panels any more than bricks or sections of timber limit existing architecture. Furthermore, given the versatility that is possible in modern prefabrication, where CNC cutters (fig. 3.7) can easily route extremely accurate individual one-off panels, there is clearly nothing to support the old fashioned concept that prefabrication is necessarily synonymous with standardisation, as embodied by the factory production lines for standard and unvarying Model-T Ford cars. Today, prefabrication has the potential to address a myriad of issues within construction, leading to cleaner, safer sites, shorter erection periods and an overall more accurate building. A construction system that performs as was intended, with human error minimised, provides an appealing alternative to the norm. The extremely high accuracy of CNC machines leads to low tolerances and subsequently fewer coordination issues for follow-on trades (Mayo, 2015). Completely individual designs are straightforward and easy to produce, their assembly facilitated by automatic labelling of each panel and precise sequencing plans; these efficiencies have the potential to raise our level of production to that which is needed. As the Egan report suggested we must use these modern advancements to improve the quality, speed and assurance of the homes we produce. The resulting gains in time and cost will ultimately allow more generous and flexible spaces as desired by families, without any losses in profit to developers and housebuilders.

Prefabrication

INDUSTRY PERCEPTIONS The growing importance of sustainability has certainly increased awareness of timber as a construction material. In response to which, several companies have been established to promote and regulate the use of timber in the UK. From the Forestry Commission and ‘Grown in Britain’, who certificate homegrown timber; to TRADA, the authority on wood in the built environment and Wood for Good, whose aim is to promote timber as a building material (Wood for Good, 2016). The recent introduction of Eurocode 5 and the National Structural Timber Specification, highlight the industry’s increasing recognition of timber as a material for modern construction (TRADA, 2015). Notably, while these companies all promote the use of timber, none currently suggests the application of home-grown timber into modern engineered products, which I believe should be a primary focus. Through groundbreaking CLT schemes, architects, engineers and developers have successfully introduced this method of construction to the UK and have thereby begun the ‘normalising’ process. It is now possible to use these schemes to convince clients of the benefits of engineered timber construction; with their exceeded site programs, excellent post occupancy reviews, and stunning timber interiors. (Westwood, 2016). Unfortunately, the industry remains sceptical and resistant to change. Lack of familiarity with CLT means that main contractors default to recommending typical solutions, and make misleading comparisons based solely on material costs per unit area to justify their choice; £190/m2 for concrete compared with £240/m2 for CLT (Smith and Wallwork, 2013). A ‘cheaper’ concrete alternative is presented to the client, with budget taking precedence over sustainability, aesthetics and safety; this can lead to a change in primary structure particularly if the project is using a design and build contract. A Hotel scheme in Shoreditch by Waugh Thistleton Architects went through this process resulting in a concrete frame. Few insurers understand CLT’s fire resistant properties which further propagates unfounded fears of fire safety and subsequent security of financial assets. Directly illustrating the savings of a CLT scheme is extremely complicated and so its benefits continue to be undersold. It is essential that designs are conceived as CLT from the offset, as this carries with it certain spatial constraints which stem from a load bearing solution. This can generate a rigour and readability to the design if implemented from the start and understood by the architect in this early phase. As regulations specific to engineered timber have only recently been developed, and there are no EU or UK standards for CLT’s performance, each supplier using different machines and offering different panel dimensions, span tables and warranties, a large amount of work is often needed to adapt a scheme to economically suit a different manufacturer’s panels. For the initial design phase the architect must choose a manufacturer’s panels to design to; a risk when there is no guarantee that they will be used in the resulting building. Involving the chosen manufacturer as early as possible would be a logical way to ensure the best design and avoid the need for later optimisation. The provision of local suppliers and the introduction of appropriate policy would alleviate these difficulties, therefore, promoting sustainable housing solutions.

CHANGING THE PATTERN

fig. 4.0: major World roundwood and sawnwood trade. drawn by author, data: FAO, 2011.

km 0 mi 0

1000 1000

UK Sawmills UK Engineered Timber Manufacturers Austrian Sawmills Austrian Engineered Timber Manufacturers

0km 20km 40km 60km 80km 100km

fig. 4.1: comparison illustrating current major sawmills and engineered timber manufacturing centres for UK and Austria. drawn by author.

HOME-GROWN TIMBER This thesis proposes that we establish the green belt as a ‘lung’ for London, thereby reaffirming it as commercial land for agriculture and forestry essential to provide for the city’s urban inhabitants. Afforestation of all available greenbelt land within areas highlighted for a new commercial forestry industry will provide London with a sustainable local source of modern construction material for its much-needed housing. The impending referendum regarding the UKs membership of the EU has highlighted our massive reliance on imported materials and products from Europe (Lichfield and Morris, 2016). A vote to leave would negate the tax advantages of the single market which are of such importance for products like CLT. We import almost all timber used for construction in the UK, homegrown timber being viewed as inadequate quality; graded to C16 where European timber is on average graded to C24 (BSW Timber, 2010). However, this has more to do with the method for grading than any substantial difference in quality. Currently, the volumes of engineered timber used in the UK are estimated to be less than 100,000m3, the majority of which is imported, including all CLT (Smith, 2015). For engineered timber to become a sustainable solution upon which we can rely, it must be grown and processed in the UK. Using home-grown timber in engineered products narrows the performance gap allowing us to begin using our timber for construction applications. With European timber, on average 10% more expensive than home-grown (BSW Timber, 2010), our CLT could become a more sustainable and cost-effective alternative to its imported counterpart. This reduction in material cost has the potential to be translated into a lower cost of homes, yet to do this we will need extensive reforestation and afforestation. A UK based factory would minimise the environmental impact related to material transport, which is currently a perverse reality of the timber industry, which is unquestionably considered ‘clean’ and ‘natural’ despite the vast transportation network underlying its usage (fig. 4.0). The establishment of new CLT factories and new forests would create jobs, which could balance those being lost in the steel industry as a result of competition from cheap Chinese imports. Recent news that major steel company Tata was forced to cut 1,050 UK based jobs (Farrell and Davies, 2016) illustrates the Government’s failure to protect UK based manufacturing centres in its bid for ‘market economy status’. By switching to home-grown CLT and establishing a new industry, we would not only create new jobs for those losing employment elsewhere in the economy, but would also protect ourselves from fluctuations in the global market.

CURRENT wood panels paper and pulp fuel, fencing etc.

13%

PROPOSED

UK Conifer Forest New Conifer Forest

AMBITION Future Conifer Forest

5% 22% 19,500ha 1,619,000ha

487,500ha

60% 6,014,600t green softwood

123,000t green softwood

68,500m3 Sawn Softwood

3,075,000t green softwood

1,712,500m3 Sawn Softwood

3,400,000m3 Sawn Softwood

NO CLT PRODUCED FROM THIS

New CLT Factory 25 New CLT Factories

60,000m3 CLT

2,000 homes a year

1,500,000m3 CLT

50,000 homes a year! (LIP TARGET)

fig 4.2: existing, proposed and ambition for UK softwood forests and annual production of sawnwood; subsequent annual CLT and possible. drawn by author, data: Forestry Commission, 2013a, b and Probert, 2016.

Changing The Pattern

Past efforts to reforest means there is a growing stock of timber, capable of supporting a 30% increase in softwood production over the next 50 years (Forestry Commission, 2014). This surplus timber could easily be channelled into new engineered timber products thereby overcoming existing buying and selling cycles. However, to maintain this increased timber production would demand the expansion in forested areas. Planning regulations around developments proposed on Greenbelt land are necessarily strict, specifying that in general any new construction is inappropriate and will not “preserve the openness of the green belt or its function” (NPPF, 2012). However, clause 9. Protecting Green Belt Land, Paragraph 89, within the regulations states that “buildings for agriculture and forestry” are an exception to this general principle. By utilising this provision within the legislation, forestry infrastructure, including sawmills and CLT manufacturing centres, could be constructed on Greenbelt land. The buildings themselves would be appropriately scaled, obscured from view and located adjacent to main arterial railway lines into London thus minimising environmental impacts and transportation costs associated with alternate infrastructure for this new industrial hub. It is proposed that Government subsidies should be made available to assist in the afforestation of suitable areas, with the intention that these would be managed as commercial forests and provide a source of income to the owners, whether they be private individuals or councils. The funding will only be available to those with proper silviculture plans and with an agreement that the timber be sold to the newly established UK-based CLT factories at Government controlled rates. The Timber Innovation Act of 2016, a recently passed US bill, pledges five years of financial support to ‘accelerate the use of wood in buildings, especially tall wood buildings, and for other purposes’ this subsequently gives a strong precedent for the proposed UK governmental support. Previous focus on establishing a direction for UK forestry led to the formation of Grown in Britain, based on ‘Recommendation 18’, part of a report by an independent panel asked to advise on this area in 2012 (Grown in Britain, 2014). This recommendation urged the Government to work with woodland owners and timber businesses to unlock the potential of home-grown timber. Subsequently, they provide licensing for every stage of the supply chain, including construction. It is therefore assumed that forests created under this scheme would be registered by this body thus integrating within this recently established framework.

Home-Grown Timber

Existing Selected Railways M25 Inner Metropolitan Greenbelt Outer Metropolitan Greenbelt Sites for aforestation and CLT production

fig 4.3: Metropolitan Greenbelt with selected existing railway lines and potential sites identified for afforestation and CLT manufacturing centres. drawn by author.

Changing The Pattern

Locally sourcing panels and distributing them into London via existing rail networks minimises the potential for transportation delays during construction and enhances the ability to respond to increased demand if projects run ahead of time. As a CLT frame requires significantly fewer loads than an equivalent concrete structure, its use would further reduce the impact on surrounding communities. The industry will be ‘no-waste’ despite not all of the log being suitable for CLT production; the rest will be utilised as biomass and pulp. To limit the impact of the local industry, it is proposed this ‘waste timber’ is used to power the industrial process of cross-lamination and the initial kiln drying of the timber, the most energy intensive process. With the sawmill and CLT factory located directly next to each other, transport impact can be further reduced, utilising waste on site also ensures no impact from its transport. It is clear the establishment of this new industry will require significant investment. While Government funding will be provided to assist in afforestation, it is proposed the UK’s largest sawmill company BSW Timber, who invest heavily in research and product development (BSW Timber, 2016) would have a vested interest in the construction of a manufacturing centre. It is in their interest to expand the UK timber industry and given the support for reforestation from the Government alongside plans to ensure increased uptake of CLT; this would be a sound investment. To prevent the development of a market monopoly, further manufacturing centres would be established in other areas of the Greenbelt by other UK timber companies. Following 15 years of research at Edinburgh Napier University, Peter Wilson and a team of researchers formed Timber Design Initiatives Ltd., a company working towards a production centre for Scottish CLT. The performance of small volumes of CLT produced from Scottish grown Sitka Spruce were subjected to four-point bending tests, which confirmed their ability to perform to the standards set by Central European manufacturers (Wilson, 2015b). Directly following this success, CCG purchased a £4.15m plant in 2015 to commence CLT production (Herald Scotland, 2015). More heavily forested than England, it is logical that Scottish CLT would come first, however, as transport from Scotland has a not disparate impact to that from Austria this does not affect the need for CLT factories serving London. Following this in February of this year, Legal & General invested £55m in a factory outside Leeds, which is to produce 3,000 prefab modular homes a year (Fraser, 2016). Their press release confirms these modular houses will be of CLT and subsequently illustrates the enormous potential CLT has for addressing the housing deficit and the anticipated capital gains (LGC, 2016). Although it is not presently clear if UK grown timber will be utilised, this precedent illustrates the investment potential and the improving knowledge base.

Home-Grown Timber

Fairmule House, Quay2c Architects, 2006 - 1 Edâ&#x20AC;&#x2122;s Shed/Sunken House, Adjaye Associates, 2007 - 2 Stadthaus/Murray Grove, Waugh Thistleton Architects, 2009 - 3 The City Academy, Studio E Architects, 2009 - 4 Berger Primary School, Studio E Architects, 2010 - 5 Bridport House, Karakusevic Carson Architects, 2011 - 6 Lauriston School, MaccreanorLavington Architects, 2011 - 7 Whitmore Road, Waugh Thistleton Architects, 2012 - 8 Gingerbread House, Laura Dewe Mathews, 2013 - 9 Ickburgh School, Avanti Architects, 2014 - 10 Curtain Place, Waugh Thistleton Architects, 2015 - 11 The Cube/Wenlock Road, Hawkins/Brown, 2015 - 12 Woodberry Down, Waugh Thistleton Architects, 2016 - 13 32a Lansdowne Drive, Tectonics, 2016 - 14 Dalston Lane, Waugh Thistleton Architects, 2016 - 15 Proposed Site 13

4 15

14 2

9 7

3 1 11

fig. 4.4: locations of existing CLT schemes within Hackney and proposed prototype site. drawn by author.

TIMBER-FIRST POLICY Architects have a responsibility to consider the ‘environmental impact of [their] professional activities’ (ARB, 2009, p5.). One way to force the engagement of those not inclined to do so, would be to introduce a carbon tax on building materials, subsequently promoting the use of low embodied carbon materials. However, this form of ‘brute force’ policy is likely to receive criticism from the steel and concrete industries. In this respect, it may be pertinent to encourage the use of timber away from political and professional pressures at a national level, and introduce measures on a smaller scale. This thesis hypothesises a scenario within which Hackney Council follows through with their ‘Timber First’ policy considered in 2012 (Hurst, 2012), which aimed to ensure all planning applications would have to illustrate that a timber structural solution was investigated as a first option. Though never introduced it is evident by the number of timber schemes within the borough (fig. 4.4) that pro-timber councillors and building control officers are in abundance. Once instigated this borough level policy would not preclude non-timber building solutions or make them costlier, but would raise awareness of timber solutions and promote compliance with Hackney’s sustainability goals. For this reason, Hackney has been chosen as the focus for the design explorations, although it is assumed that other boroughs would emulate the policy once the time and cost savings were demonstrated. This would then form a solid basis upon which to form a counter argument to the aforementioned issues regarding substitution of CLT for concrete or steel; as obtaining planning permission could be compromised if a non-timber solution were proposed where timber was feasible. As a result of this policy change the uptake of CLT structures should increase substantially within the borough, providing a great deal of data upon which savings can be approximated. This way the cost analysis of CLT schemes can become more accurate and industry knowledge will be increased; subsequently avoiding the tendency to reject timber due to uncertainty. Issues surrounding the differences in span tables and panel dimensions should be eased by the introduction of local manufacturers, as it is assumed that local sourcing would also be in line with sustainability aims, predetermining the supplier subsequently leading to a reduction in costs and structural redundancies resulting from later adaptations and optimisation of designs. David Cameron’s recent pledge to provide 200,000 ‘starter homes’ at 20% below market rates by 2020 (BBC, 2015) has allowed these homes to replace current requirements for social housing. Research suggests anyone earning below £77,000 will be unable to buy this housing (Emmett and Van Lohuizen, 2015), leaving their affordability in doubt and causing grave concern for how we are to provide for a vast portion of the capital. With no regulations on resale after five years, this is set to become an investment mechanism for those not truly in need. To address this, it is proposed that Hackney will only approve ‘affordable homes for sale’ with the agreement to implement a model similar to Pocket Living; a small London developer who sell apartments at 20% below market rates to first-time buyers, which can only be sold on under the same conditions (Pocket, 2016). With the additional savings of CLT, it should be possible to incorporate social housing and ‘affordable’ homes based on the Pocket model but expanded to allow for a wider clientele than just that of a single bed flat, with the prerequisites that the schemes be constructed using home-grown timber, subsequently promoting the material.

A NEW ARCHITECTURE

Graveney Sixth Form

Murray Grove Residential

fig. 5.0: comparative analysis of volumes achievable in a typical educational CLT block; Graveney Sixth Form by Urban Projects Bureau and a typical residential CLT block; Murray Grove by Waugh Thistleton Architects. drawn by author.

ADVANTAGE FROM ADVERSITY Suggesting such a widespread adoption of this new construction method gives us the potential and responsibility to critique our current approach to housing solutions. To innovate within our design of homes, we must identify those areas where current provision fails and ensure that our new approach to design using home-grown CLT will improve upon this, therefore justifying the necessary investment. Currently, CLT is primarily utilised within two sectors, that of lowrise education schemes and residential low to mid-rise towers. The application of the material for these two typologies varies accordingly (fig. 5.0). CLT was primarily introduced into UK construction for school buildings and is becoming well known and loved for the shortened assembly periods it offers. Off-site prefabrication and the simplicity of a panelized structure improves the speed and ease of assembly when compared to other construction methods. Consequently, this can allow for whole buildings to be constructed within the summer holidays â&#x20AC;&#x201C; a critical criterion for this sector. Furthermore, the real potential of CLT comes not from variation in the panels produced, but from each panelâ&#x20AC;&#x2122;s ability to be shifted, turned and rotated to virtually any position and orientation, allowing for a seemingly infinite number of possible spaces to suit different site conditions and requirements. This has partly been taken advantage of within the design of educational facilities, as their irregular programme necessitates variation in volumes to some degree; CLT enables this with an ease not so apparent in other methods. Despite these fundamental benefits, the full, structural advantage that CLT provides over traditional frame construction is not fully utilised in these low-rise applications. The second sector with which this thesis is directly concerned is that of housing. The typical application of the material for this typology is considerably different. For residential schemes, CLT is almost exclusively used as traditional platform construction whereby walls are built, upon which the subsequent floor is fixed; this process is then repeated, building the next set of walls directly above. In traditional timber construction, these walls and floors would have been framed elements, whereas beneficially with CLT, the use of panels allows for this basic system to provide enclosure and structure through one element, further simplifying the building. Initially, this can appear as an ideal approach, with residential floor plates often repeated through the levels of a building; this concept developed for individual housing can be used for higher rise structures, taking advantage of CLTs structural capabilities. However, the general assumption that these techniques can be directly transferable from three floors to twenty is naĂŻve, and we must appreciate that these building techniques must be adapted and refined to suit a larger scale of application. It is similarly clear that this simple platform construction restricts the possible volumes in a way that is not the case in the education sector. In theory, the same flexibility in the assembly of the panels is feasible within residential schemes. However, the tendency to repeat floor plates throughout the height of a residential building with little variation, coupled with the close relationship between the minimum requirement for ceiling heights and the standard width of a panel, have led to the near unanimous adoption of this method and no variation in the volumes provided. This subsequently means that contrary to our cause, the use of a CLT structure within residential schemes can exacerbate the tendency to build to the aforementioned minimum housing requirements. Platform construction encourages repeated identical single storey levels, which form a dense honeycomb of walls and an unadaptable configuration that conforms solely to minimum space requirements.

During construction panels used vertically can be unstable.

If cut down panels are used this requires a significantly higher number of lifts and joints.

fig. 5.1: issues with existing methods for using conventional panels for higher ceiling heights in residential schemes; instability for vertically oriented panels during construction and increased number of lifts and joints if panels are all cut to the required height. drawn by author.

A New Architecture

Orienting the panels vertically to allow for higher ceilings, would either require panels to cross several floors, straying from the platform method and leading to potential stability issues during assembly, or in cutting down panels into smaller pieces (fig. 5.1). As a consequence, more joints would be necessary, reducing the structural efficiency and requiring a greater number of lifts, with subsequent cost and time implications. While architects should investigate the full potential of CLT ensuring the material is pushed, it must be assumed that the proposed home-grown CLT will also appeal to and be used by the volume housebuilding industry and that they are unlikely to invest in this level of design innovation, at least in the systems infancy. For this reason, it seems prudent to use this resounding tendency towards this structural approach as a mechanism to improve the overall quality of the housing stock produced from â&#x20AC;&#x2DC;home-grownâ&#x20AC;&#x2122; CLT. While proposing to manufacture CLT, through an increase in the standard panel width produced, an increase in the standard new build room height can be shrewdly enforced, creating more generous volumes. However, this increase in standard width must also be holistically considered. Currently, the most common machinery used for the manufacturing process is a hydraulic press, due to greater flexibility for automation of the production process. They can easily incorporate the application of adhesive, the lifting and positioning of layers while also adjusting the particular pressures applied. The size of panels produced can also be easily adapted and in theory, this entire process can be automated, which if the same type and dimensions of board are being manufactured, can speed up the process giving a greater yield (Brandner, 2013). Due to this potential for automation, these presses are used more commonly however at the moment this machinery limits the panel size to 3.5m wide. Currently, panels are typically manufactured to a maximum width of 2.4m to allow for flatbed transportation on a lorry. However, it is also possible to transport the panels vertically on an A-frame that allows for slightly wider panels at around 3.5m. With both of these existing systems easily incorporating a slight increase in width to 3.5m, it can be argued that this is a sensible dimension to propose. Manufacturing these wider panels would ensure ceiling heights of above 3m, relating much more to the high ceilings of traditional townhouses. More generous, open rooms create a much better atmosphere and if sufficient, open the potential for flexibility; to provide temporary mezzanine levels to accommodate extra spaces for childrenâ&#x20AC;&#x2122;s play areas or additional bed spaces. Allowing the apartment to begin to relate to the provisions of a house, creating additional space without having to move property. Equally, these can be reversed and the generous open ceilings can be restored once the situation reverts; for example, once children have left home. This flexibility in housing has essentially been eliminated entirely from the housing stock we are currently building. We desperately need a new form of urban dwelling that people aspire to own and which is of a quality and nature relatable to traditional townhouses and suburban housing.

Advantage from Adversity

fig. 5.2: conventional platform construction; illustrating â&#x20AC;&#x2DC;squashingâ&#x20AC;&#x2122; of the floor panels. Alternate proposed construction with hung floor panels. drawn by author.

A New Architecture

In proposing this increased panel size, we must consider that assuming all else remained constant we would use a slightly higher volume of timber per dwelling. This could influence not only the potential cost but could mean fewer floors were possible where strict height regulations are in place. There would be additional delivery loads due to upright transportation as opposed to flatbed, and larger panels could be harder to assemble. These initially perceived disadvantages may cause early concern, however, as these CLT panels are to be produced from cheaper ‘home-grown’ timber, it can be argued that the cost could become equivalent to that of European CLT of a smaller width. Equally, reduced transport cost could mean that ‘home-grown’ CLT panels become economically attractive. If we optimise the CLT structures created by designing in a timber-oriented way, then there is potential to reduce the overall quantity of CLT needed for the main structure. This brings with it many benefits and ensures that the additional timber necessary for the increased panels are more than ‘balanced out’ concerning quantity and cost, through intelligent design. An example of timber specific design creating more potential within the material and subsequently using reduced quantities of timber, can be seen in the design of Waugh Thistleton Architect’s Whitmore Road project. To provide a large completely open space for a photography studio on the middle floor, the party walls of the flats above were designed to act as beams, with the façade either side acting as trusses. Subsequently, this influenced the design and allowed the panels to be thickened or reduced relative to the stress in any given area. This optimisation was able to reduce the volume of timber used per m2 to two-thirds of that used in their renowned Murray Grove scheme (Waugh, 2015). Towards the same goals, their Dalston Lane scheme, currently under construction, has been designed to allow for reduced wall panel thicknesses on higher floors where the loads are reduced, from 140mm panels on the first floor to 90mm at the top floor (Waugh, 2016). As a principle, platform construction was not designed for buildings of significant height as seen in today’s cities. This system needs to be reconsidered and elements of it adapted. At a basic level, timber is strong under compressive loads that travel down the grain but with forces perpendicular to the grain timber can be easily compressed and deformed, particularly within taller blocks with more self-weight (Lawrence and Abeysekera, 2015). Consequently, within the design development, it is assumed each CLT wall panel is fixed directly on top of the wall below, the floors hung on brackets (fig. 5.2). This will avoid the building ‘sinking’ due to compression of the floor plates. Accordingly, the introduction of wider ‘home-grown’ panels will become even more important as this further reduces the floor to floor height overall compared to platform construction configuration.

Advantage from Adversity

fig. 5.3: photographs of â&#x20AC;&#x2DC;Naked Houseâ&#x20AC;&#x2122; model, illustrating concept of personalised prefabrication and utilisation of waste from cut outs. source: http://drmm.co.uk/projects/view.php?p=naked-house

fig. 5.4: methods of producing openings, subtractive CNC routing vs. additive joining of panels. drawn by author.

DESIGNING IN TIMBER As CLT forms a structural load-bearing solution through solid panels acting as both structure and enclosure, the consideration of this within the design is essential from the offset. This dual role should be an extremely appealing concept, however, it is often seen as restricting rather than an advantage due to the current tendency to cover CLT walls and floors with plasterboard limiting this benefit. Theoretically openings of any size, shape and position can be precut into a CLT panel in the factory, allowing extremely high accuracy, ease of assembly, and freedom in the design of openings. However, in this system of cutting openings, several issues become apparent. The first is that of waste. The less regular the cutout, the less likely it can be used elsewhere within the building or on another scheme. The idea of using CLT for furniture within the building to avoid its waste was partly explored by dRMM through their project ‘Naked House’ (fig.5.3) (de Rijke, 2015). While this proposal was interesting in highlighting very directly the potential misuse of the material, the relatable connection between the furniture and the openings in this project dictates a very specifically planned space, allowing for limited flexibility in the indented use. Additionally, the level to which thick elements of CLT are appropriate for, or appreciated as, furniture is not clear. In reality, very few projects use quite such irregular shapes as ‘Naked House’, however, the issue of waste still holds true for regularly shaped openings. The proposed ‘home-grown’ timber industry has the potential to be zero waste, as previously described due to utilising the entire log. The use of non-toxic Purbond glue, amounting to less than 1% of a panels volume (Waugh, 2015), means that cut outs could also be used for pulp or biomass. However, as these parts have already been processed, are of higher quality, and have the potential to store their absorbed CO2 rather than re-emitting this as they degrade or burn, it is essential that through the design we minimise waste originating in this way. As an industry response, it is now relatively common practice to form openings by joining smaller sections of CLT around the required opening rather than CNC routeing it out (fig. 5.4). This practice avoids waste but fundamentally undermines the benefits of prefabrication resulting in an increased number of lifts and joints, subsequent loss of structural strength and a reduced level of accuracy. Alternately, by considering that a structure will be CLT from the offset it is possible to aim to minimise ‘cut outs’ through the design process which can subsequently help to develop a specific language for these buildings. By designing full height openings and considering the relationship between the proportion of rooms and the module of a panel, the volume of waste can be reduced.

fig. 5.5: early concept model, exploring the potential spectrum of facade openings from â&#x20AC;&#x2DC;cutoutâ&#x20AC;&#x2122; to full height for a typical grid block and the implications of a cellular vs. a more open arrangement. model and photographs by author.

A New Architecture

Intended occupants should have an input into housing design, it seems counter intuitive that in most cases they simply donâ&#x20AC;&#x2122;t. Self-build and the new rightto-build scheme stem from this principle and hope to allow this portion of construction to allow user input thus leading to higher quality developments due to vested interest by those undertaking the design and construction (Wilson, 2015a). However, it is unfeasible that this sector alone would be able to meet all our housing needs and so it is essential that user input can be included in all dwelling production. With the further complication that dwellings can be sold on and so should be flexible, coupled with the understanding that family circumstances change and so require built-in adaptability, it seems that a level of adaptability and flexibility for multiple changes through a buildingâ&#x20AC;&#x2122;s life is essential. Furthermore, if truly flexible buildings are to be designed, then it should be possible to convert a housing unit, to a work unit, or a live/work unit, or potentially even more abstracted programmes. If all our space were sold purely on the square footage it provided, then people would have a far greater understanding of what potential their dwellings held for adaptions to suit their changing situations. Subsequently, the longevity of a building would be increased and communities would have time to develop within high-density dwellings the same way they did in traditional streets. Typically, CLT is used as a giant honeycomb structure, where all the walls within a residential building are assumed to carry some load. As loads are easier to calculate for a frame with definite points of transfer, panelised design is harder to optimise. Unsure of exactly where the load paths lie, CLT is often over-engineered (Lawrence and Abeysekera, 2015), where every wall within the building is considered structural. This combined with all precut openings substantially limits the potential to adapt the flatâ&#x20AC;&#x2122;s layouts at a later date. In order to avoid this dense honeycomb arrangement, it is essential to look at the factors specific to timber that govern the required structure for buildings of this sort. Despite using far more timber than traditional frames, CLT frames constructed of softwood are comparatively light. Subsequently, it is overturning due to wind loading, as opposed to providing structure for carrying loads from the weight of the building, which are of concern (Lawrence and Abeysekera, 2015). Interestingly, aligning with aims to minimise waste, the key to creating an optimised structure which prevents these wind loading issues is possible through the incorporation of unpenetrated shear walls, perpendicular to the facades, to resist these forces (Lawrence and Abeysekera, 2015). Typically, the internal walls containing the least openings lie between the flats and the core or between two flats, with each only requiring one or two entrances, however with a typical square core configuration the lengths of walls required allow no-where to position these primary doors without penetrating the walls. As coupling within a timber structure is not effective in the same way as with reinforcement in concrete, the requirement for these unpenetrated lengths of wall has driven the internal layout within the design proposals.

Designing in Timber

fig 5.6: iterative development models of â&#x20AC;&#x2DC;windmillâ&#x20AC;&#x2122; based structural system to suit site constraints and context; work in progress. model and photographs by author.

A New Architecture

By proposing a ‘windmill’ configuration, the required lengths of wall, in relation to the facades are possible while still allowing access to each flat from the central core. This concept can be adapted to suit variations in shape and form due to site requirements allowing the provision of these stability walls and flexible flat interiors without compromising on massing and site relationship. This has driven the initial investigation for a prototype scheme in Hackney. The iterative models in fig. 5.6 illustrate the development from a basic structural form to suit the site. The inclusion of these walls of sufficient length not only steer the design towards eliminating waste but through the considered design of the structure, allow for much more open, flexible spaces within the flats themselves. Combined with the greater flexibility provided by the higher ceilings, these new homes are capable of accommodating changes in family circumstance or even changes in use. Designing with panels can be seen as constricting regarding internal planning when compared to a column arrangement, as such this concept of flexible spaces has been key to this research. With the above structural system in place, the space within the flats can be left relatively free of structural elements and need not be divided by CLT walls, the use of which would require unnecessarily large quantities of timber. It is naïve to assume that all our ‘home-grown’ CLT will be utilised in this way, and it must be understood that we are also likely to create many typical honeycomb tower blocks, produced by volume housebuilders in the same way they are today. The increased panel widths for these structures becomes even more vital to ensure that overall, we create more generous volumes, and it, therefore, lies within the role of the architect to innovate within the scope of the material and push what is possible by considering the structural potential. In this way, the relationship between architect and engineer becomes an increasingly collaborative design process leading to more efficient sustainable responses to urban housing.

Designing in Timber

fig. 5.8

fig. 5.7

fig. 5.9

fig. 5.10

fig. 5.7: sweet chestnut cladding, fig. 5.8: plasterboard covering. Whitmore Road, Waugh Thistleton Architects, Mixed use, residential and commercial scheme. fig. 5.9: Translucent cladding, fig. 5.10: exposed CLT. Graveney Sixth Form, Urban Projects Bureau, Education sector scheme. photographs by author.

A NEW AESTHETIC For years, we have built timber framed houses, clad in brick to appear as masonry construction. Partially stemming from fear and paranoia towards the perceived fire risk and partly as a result of building regulations which favoured non-combustible materials. The development of UK building regulations originated following the Great Fire of London (1666) and intended to prevent the spread of fire through party walls, ensuring that if one did break out it would be unable to spread so extensively (Calder, Senez and McPhee, 2014). These regulations have been minimally adapted since then, the fear still very apparent nearly 400 years on. Technologies have completely changed and while the properties of mass timber elements such as CLT are well known, we are reluctant to embrace its benefit in this regard by choosing to meet regulations solely through plasterboard linings. While suggesting such an extensive uptake of CLT construction, it is essential that we not only consider the implications and benefits of this material spatially and structurally but that we consider the aesthetic and atmospheric qualities that an ‘honest’ expression of CLT can offer. To date exposed CLT in the UK is seen largely only within low rise educational facilities (fig 5.10). Regulations are considerably different for a building of this sort with fewer acoustic requirements and greater ease of evacuation. Although exposing the timber in residential buildings requires more significant thought during the design process, it is essential that we learn from the precedence within these school buildings despite the differing use. The improved spatial qualities within the new CLT housing should alone make this new housing aspirational, subsequently creating demand and increasing uptake, however, a more direct representation of the material not only benefits this aspiration to re-educate the population but can also have benefits to the occupants. Engineered timber has not had a sophisticated aesthetic developed in the same way that concrete and steel have, it needs to be identifiable, its physical appearance, associated with the forms resulting from timber orientated designs should drive its use. Timber is instinctively appropriate for housing, due to its connection to nature and the environments that it creates. A study in 2009 by the Human Research Institute illustrated that a timber environment in schools can have a positive impact on children’s learning abilities, their heart rates are lowered, showing reduced stress and improved concentration (Stora Enso, 2014). Timber regulates moisture and temperature, creating a more natural environment. It’s tactile, irregular surface gives more interest and character to a space, along with a sense of individuality. We have become so used to veils of plasterboard which do not illustrate any different between a solid load bearing element and a hollow stud partition, CLT elements are more true to their appearance as a solid structural mass.

fig. 5.11: traditional stave church c.1200, Norske Folkemuseum. photograph by author.

A New Architecture

However, there is a common assumption that CLT has lost the beauty of traditional timber construction, that which is directly relatable to the size, scale and tactility of a tree and performs structurally in the same way that a tree would. In some traditional methods, particularly those of Nordic Stave Churches (fig. 5.11) and Viking ship construction, curved root sections from the base of trees were specifically sourced for their precise shape and size such that the natural form of the timber carried loads in the direction required. Searching for the perfect tree was intensive and required a great deal of skill and knowledge (Host, 2014). For CLT on the other hand, the panel size and performance exceeds its constituent elements opening up its vast potential while also straying from the perception of what seems possible in timber. CLT is often hidden, undeclared and unexpressed in the design of the form, structure or skin. Where CLT is exposed, it is often only one panel/wall, which gives very limited information about the system that appears as a relatively flat surface and so does not express its structural role. The honesty of technological manufacturing has, in the past, been developed into a distinct aesthetic that illustrates its process. This is particularly the case for concrete formwork, where the choice of size, species, orientation and spacing of panels and fixings are carefully considered and expressed more or less evidently across different areas or buildings as a feature. If CLT learned from these previous developments expressing the composite system in a readable manner, then this would lead to an honest aesthetic, which could be refined to be recognisable. Visible quality CLT usually has an appealing, uniform surface, with a subtle grain due to the light colour of the timber used. As with any large relatively uniform surface, this can seem un-relatable to the human scale that is so vital for domestic environments. It is possible to paint, varnish and stain CLT surfaces however these decisions are difficult to reverse without planing, which eventually would have structural implications. For this reason, I propose providing aesthetic interest, offsetting the large panels by the means of ornament through furnishings and the more temporal structural elements that are required to subdivide the open space. With this in mind, I have considered the potential for these temporary spatial components to be constructed using traditional timber framing. These room divisions, partitions and even platforms, would be adaptable and could change over time but would offset the vast CLT faces, particularly if a different timber was used, also providing a change in colour. The timber framing could provide more permeable or opaque divisions depending on their construction and infill. In this sense the CLT acts as a neutral background, but with a connection to these elements of traditional timber craft, allowing us to re-engage with different levels of the timber industry and relate to different proportions.

A New Aesthetic

structural width redundant structure

structural width

charring layer

FIRE

Conventionally oriented panel

charring layer

FIRE

Alternately oriented panel

fig. 5.12: diagram illustrating conventionally oriented panel suitable for exposure on one side, and equivalent thickness panel with external layers in the non-structural orientation suitable for exposure on both sides. drawn by author.

A New Architecture

To allow internal exposure, the panel thicknesses must be increased to accommodate the additional charring layer. One-hour fire protection requires around 40mm of sacrificial timber; the rate at which it burns being very well established and extremely predictable, around 0.7mm per minute. Using external sacrificial layers of CLT in the non-load-bearing direction has potential to allow slightly thinner walls where panels are to be exposed on both sides (Owarish, 2015). Since these layers are not structural, the charring does not affect the thickness of the structurally functioning portion of the panel (fig. 5.12). However, where the CLT is to be exposed to only one side, this approach could require the same or greater volumes of timber than a typical response due to redundant non-structural timber being provided on the protected face. For this reason, each wall should be evaluated on a case by case basis to ensure that the minimum sacrificial timber is utilised in each instance. CLT is a solid load bearing system, and it appears as such. In this sense, the combination of these solid elements with lighter timber infill forming temporary divisions within the open plan volume also provides an intriguing aesthetic quality as juxtaposed elements of this different nature can illustrate the full spectrum of timber architecture. This, in turn, can lead to a second layer of readability so that the thickness of the element reflects its permanence. The fire integrity of the finer timber framing elements would unlikely be sufficient, however assuming they do not form any part of the structure of the building it could be assumed that these elements are designed as temporary â&#x20AC;&#x2DC;furnishingsâ&#x20AC;&#x2122;. This will enable them to be adapted and changed without affecting the safety of the building and would allow for them to be exposed, showing the true contrast between these two levels of timber construction. Acoustics are another key issue for consideration if the CLT is to be exposed. Plasterboard is often needed to contribute to the acoustic performance of the CLT itself to meet regulations. As in many cases, the CLT will only be exposed to one side it is thereby possible to provide the acoustic insulation to that face and to ensure adequate detailing. As timber is lightweight, a significant issue can result from flanking vibrations due to impact. Structurally it can be beneficial to span floor panels across walls. However, this must be limited to internal walls within apartments and not party walls to avoid this issue (Waugh, 2015).

A New Aesthetic

fig. 5.13: triptych, analysis of aesthetics of timber homes. artwork by author.

A New Architecture

The potential to expose CLT externally has been explored to a lesser degree. Spruce is not a weather resistant species and moisture ingress, particularly into the end-grain of the timber is a high risk, making it susceptible to rot. The detailing of any coverings to prevent this action would need to be well designed and executed. Another issue to consider is that CLT does not perform thermally in a sufficient manner alone unless it is in extremely thick panels, so must usually be insulated on one side. The award winning ‘Architecture Archive’ by Hugh Strange Architects uses a single layer of CLT without insulation, cladding or lining, built within a retaining brick structure with an oversailing roof to protect from driving rain (HAS, 2014). In this case, the exposed timber internally allows regulation of the moisture content to preserve the drawings kept within, the thickness of the walls illustrate that without insulation, if regulations are to be met, then a vastly greater volume of timber is needed, which has certain implications, including spatially. The simplicity of CLT providing the entire structure, enclosure and insulation is a fascinating concept and is both very honest and heavily reflects traditional forms of shelter. The relative ‘chunkyness’ of CLT panels is another aspect that should drive its aesthetic form. The modern obsession with aesthetic ‘thinness’ must be reconsidered. The deep reveals formed by openings within CLT panels can ensure the relationship between this and the shadows it forms strongly influence the façade. Considering the substantial issue of waste, it is proposed that rather than limiting openings or suggesting an alternate use for the cut out timber, that façades should be formed of full height sections of solid and void, avoiding ‘punched windows’ wherever possible. This would further aid in the aesthetic readability of these buildings as being CLT construction by establishing this common aesthetic quality. The consequences of this concerning structural performance need to be investigated for each scheme to ensure that the floor slabs can still span from the main structural walls out towards the façades. The desire to emphasise the solidity of the CLT reinforces this concept of strong solid and void elements within the façade. The reveals are an important aspect for truly understanding the materials engineering as this ‘end on’ section of the panel, wherein the individual lamellas are visible, creates an honest representation of the process (fig. 5.13). From this, it is clear that to benefit from what CLT can provide to improve the quality of people’s homes it is necessary that we come to associate the construction method with the spatial qualities it can afford. To achieve this, the material must be celebrated and visually expressed. This will allow a sense of identity to be endowed with each new development, and the material choice as a whole, which often until now has been mostly hidden from the public view.

A New Aesthetic

CONCLUSIONS As a new material vying for acceptance as a standard building solution alongside concrete and steel, CLT has its greatest struggle concerning its perception and a lack of understanding causing a sense of risk within the industry. To receive appropriate recognition, deeply held misconceptions from the past related to prefabrication and safety must be corrected. Without data to back up the claims made by manufacturers and architects, contractors and clients fundamentally tend towards decisions based on familiarity, despite CLT’s myriad of benefits to construction, regarding speed, safety and accuracy. It is essential that timber is promoted as a building material at a higher level, to raise its awareness and demand. Existing precedent supports the proposal for both local authority ‘Timber First’ schemes, to promote timber through the planning process, and higher level government funding to support the establishment of a ‘home-grown’ timber industry. The development of UK-based manufacturing centres would not only combat the hypocrisy of the extreme global nature of the ‘clean’ timber trade, but would also provide a genuinely sustainable self-sufficient supply of building materials. By siting manufacturing centres within reforested areas surrounding our cities, we can increase woodland coverage, reduce the environmental impact of transportation, create jobs in forestry and manufacture, and instigate a use of areas whose untapped potential has been ignored due to regulations limiting their use. Furthermore, the creation of this UK industry would protect our housing efforts from fluctuations in the international material market. Ensuring that the provision of materials for our house-building efforts are not susceptible to variations in availability, cost and tax of imported materials; and that we, as a nation, are not at the mercy of foreign suppliers. Educating the entire industry to use and understand CLT, with its implications for programme and procurement, is essential to highlight its advantages and increase its uptake. The more commonplace and accessible this method becomes, the more cost-effective and user-friendly it will be. It is essential that in the provision of our next ‘generation’ of housing, we learn from past efforts and provide the quality and flexibility critical to modern living. If we can incentivise a change in primary building material through its sustainable merits and the benefits regarding its cost, accuracy, and ease of construction, then we should ensure that this shift in construction methodology has a subsequent positive effect on the spaces it provides. Ensuring that the homes built reject the typical unadaptable model and become a typology valid for our urban housing future.

Home-Grown Housing

In suggesting such a radical overhaul of our primary mechanism for constructing urban housing, it is essential that the modern prefabricated system employed revolutionises the quality and appropriateness of the homes created. The understanding of how to gain the British publicâ&#x20AC;&#x2122;s acceptance by drawing on aspects of traditional housing with an inherent need for adaptability would allow the introduction of CLT as a construction material without opposition. The incorporation of this generous, adaptable, and flexible space ensures the architect is required to address the problem at a multitude of scales: to create spaces which work for its myriad inhabitants. By this school of logic, we have seen a place for all aspects of timber use from traditional craft through to large scale engineered industrial production. The homes provided can benefit from the natural qualities of timber and more generous flexible spaces, which are possible when buildings are designed with CLTâ&#x20AC;&#x2122;s unique properties in mind. Due to the restricted scope of this research, there were inevitably limitations to the extent of my study. One aspect which I was unfortunately not able to develop more fully, was that of optimising the joints between CLT panels. Initial concept designs proposed the use of an interlocking system building upon traditional joinery, which used the joint itself and the self-weight of the panels to hold the building together, thus eliminating the need for vast quantities of screws and brackets, which are likely to have a shorter lifespan than the panels themselves. This reliance on interlocking joints is not necessarily compatible with the structural system I have developed. However, reducing the emphasis on metal fixings, along with optimising typical lap joints to utilise whole lamellas subsequently reducing waste, are essential areas for the development and progression of CLT structures and would be an interesting area through which to extend and consolidate this research. The research undertaken has ascertained a strong argument, that in order to progress the building industryâ&#x20AC;&#x2122;s sustainable efforts, we need to ensure the mainstream adoption of this carbon-mitigating construction across London and the rest of the UK. Through the establishment of design principles which stem from the positive properties and qualities of engineered timber, the adoption of this material can become synonymous with a design approach that is not only true to the material and subsequently more efficient, but which provides a more generous appropriate dwelling form. These factors combined enable housing production at a scale which can combat our spiralling housing crisis, using a system that does not thwart, but instead helps to meet the essential climate goals of this generation and generations to follow.

Conclusions

LIST OF FIGURES Our Housing Predicament 1.0 1.1 1.2 1.3 -

Number of Homes Built Annually in London. Drawn by author, data: GLA, 2015. Diagram illustrating the proposed ‘user cycle’ for mixed developments. Drawn by author. Leslie Martin and Lionel March’s ‘pavilion’, ‘street’ and ‘courtyard’ massing forms. Drawn by author, data: Towers, 2015. Comparative areas of new build dwellings. Drawn by author, data: Roberts-Hughes, 2011.

The Sustainability Imperative 2.0 2.1 2.2 2.3 2.4 2.5 -

Current UK emissions vs. set reduction targets. Drawn by author, data: Department of Energy & Climate Change, 2013. Comparative impact of concrete, steel and CLT. Drawn by author, data: ASBP, 2013 and Hammond and Jones, 2008 Rewritten, pro-timber story, undoing the negative perspective of timber perpetuated through fairytales such as the ‘Three-Little-Pigs’. Artwork and photograph by author. European percentage forest coverage by country. Drawn by author, data: SCBD, n.d. Commercial forest; thinning and transportation, Norway. Photograph by author. Recreational forest, England. Photograph by author.

Twenty-First-Century Timber 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 -

Manufacturing process for cross-laminated timber. Drawn by author. Woodberry Down under construction, Waugh Thistleton Architects. Photograph by author. Dalston Lane under construction, Waugh Thistleton Architects. Photograph by author. Ronan Point following gas explosion and progressive collapse. Retrieved May 2016 from: http://www.failedarchitecture.com/thedownfall-of-british-modernist-architecture/ Ronan Point following gas explosion and progressive collapse. Retrieved May 2016 from: http://www.bdonline.co.uk/precastdisaster/3087206.article Humidifier, KLH manufacturing centre, Katsch an der Mur, Austria. Photograph by author. Main Warehouse, KLH manufacturing centre, Katsch an der Mur, Austria. Photograph by author. CNC Router, KLH manufacturing centre, Katsch an der Mur, Austria. Photograph by author. Surface finishing/sanding, KLH manufacturing centre, Katsch an der Mur, Austria. Photograph by author.

Home-Grown Housing

Changing the Pattern 4.0 4.1 4.2 4.3 4.4 -

Major World roundwood and sawnwood trade. Drawn by author, data: FAO, 2011. Comparison illustrating current major sawmills and engineered timber manufacturing centres for UK and Austria. Drawn by author. Existing, proposed and ambition for UK softwood forests and annual production of sawnwood; subsequent annual CLT and possible. Drawn by author, data: Forestry Commission, 2013a, b and Probert, 2016. Metropolitan Greenbelt with selected existing railway lines and potential sites identified for afforestation and CLT manufacturing centres. Drawn by author. Locations of existing CLT schemes within Hackney and proposed prototype site. Drawn by author.

A New Architecture 5.0 -

5.1 5.2 5.3 -

5.4 5.5 -

5.6 5.7 5.8 5.9 5.10 5.11 5.12 -

5.13 -

Comparative analysis of volumes achievable in a typical educational CLT block; Graveney Sixth Form by Urban Projects Bureau and a typical residential CLT block; Murray Grove by Waugh Thistleton Architects. Drawn by author. Issues with existing methods for using conventional panels for higher ceiling heights in residential schemes. Drawn by author. Conventional platform construction; illustrating ‘squashing’ of the floor panels. Alternate proposed construction with hung floor panels. Drawn by author. photographs of ‘Naked House’ model, illustrating concept of personalised prefabrication and utilisation of waste from cutouts. Retrieved May 2016 from: http://drmm.co.uk/projects/view. php?p=naked-house Methods of producing openings; subtractive CNC routing vs. additive joining of panels. Drawn by author. Early concept model, exploring the potential spectrum of facade openings from ‘cutout’ to full height for a typical grid block and the implications of a cellular vs. a more open arrangement. Model and photographs by author. Iterative development models of ‘windmill’ based structural system to suit site constraints and context; work in progress. Model and photographs by author. Sweet chestnut cladding, Whitmore Road, Waugh Thistleton Architects, Mixed use, residential and commercial scheme. Photograph by author. Plasterboard covering, Whitmore Road, Waugh Thistleton Architects, Mixed use, residential and commercial scheme. Photograph by author. Translucent cladding, Graveney Sixth Form, Urban Projects Bureau, Education sector scheme. Photograph by author. Exposed CLT, Graveney Sixth Form, Urban Projects Bureau, Education sector scheme. Photograph by author. Traditional stave church c.1200, Norske Folkemuseum. Photograph by author. Diagram illustrating conventionally oriented panel suitable for exposure on one side, and equivalent thickness panel with external layers in the non-structural orientation suitable for exposure on both sides. Drawn by author. Triptych, analysis of aesthetics of timber homes. Artwork by author.

Cover Images Print on front cover, aesthetic of timber interiors. Artwork by Author. Inside cover, aerial of Austrian forest illustrating ambition for proposal. Retrieved April 2015 from: https://www.google.co.uk/maps/place/Austria/ (Satellite aerial image) List of Figures

BIBLIOGRAPHY Books and Articles Benevolo, L., 1971. History of Modern Architecture, Volume two; The modern movement. (Translated from Italian by Landry, H. J. ) London: Routledge and Kegan Paul. Bernheimer, A., 2014. Timber in the City: Design and Construction in Mass Timber. China: ORO Editions. Brandner, R., et al., 2016. Cross laminated timber (CLT): overview and development. Berlin: Springer. Brown, N., 1967. The form of housing, Architectural Design, p432-433. London: Wiley. Brunskill, R. W., 1971. Illustrated Handbook of Vernacular Architecture. London: Faber and Faber. Brunskill, R. W., 1994. Timber building in Britain. 2nd ed. London: A Cassell imprint. Calder, K., Senez, P. and McPhee, R., 2014. The Risk Basis for Height and Area Limits in North American Building Codes. Quebec City, Canada: World Conference on Timber Engineering. Davies, C., 2005. The Prefabricated Home. London: Reaktion Books Ltd. Gilbert, H., 1984. The Dream of the Factory-Made House, Walter Gropius and Konrad Wachsmann. America: The MIT Press, Halliday Lithographic. Jacobs, J., 1961. The Death and Life of Great American Cities. New York: Random House. London County Council, 1937. London Housing. London: London County Council. Mayo, J., 2015. Solid Wood: Case Studies in Mass Timber Architecture, Technology and Design. Oxon: Routledge.

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Peterken, G.F., 1993. Woodland Conservation and Management, 2nd ed. London: Chapman and Hall. Radkau, J., 2012. Wood A History, English ed., Cambridge: Polity Press. Sergeant, J., 1984. Frank Lloyd Wright’s Usonian Houses, The Case for Organic Architecture. New York, USA: Whitney Library of Design, Watson-Guptill Publications, Billboard Publications Inc. Sert, J. L., 1942. Can our cities survive? 2nd ed. Cambridge, Mass: MIT Press Shaw, E.M., 1872. Fire surveys: or, A summary of the principles to be observed in estimating the risk of buildings. London: E. Wilson. Smith, S., 2015. British Timber in Construction. ICE Construction Materials Journal. Cambridge: Smith and Wallwork Engineers. Smith, S., 2013. Grown in Britain – a review of the use of timber in UK construction. The Structural Engineer, P.54-56. Stebbing, E.P., 1919. Commercial forestry in Britain; its decline and revival. London: J.Murray. Swenarton, M., 2012. Developing a new format for urban housing; Neave Brown and the design of Camden’s Fleet Road estate, The Journal of Architecture, 17:6, p9731007. London: Routledge. Thompson, H., 2009. A Process Revealed, London: Fuel Publishing. Towers, G., 2005. At home in the city; an introduction to urban housing design. Oxon: Architectural Press, Routledge. Unwin, R., 1909. Town Practice in Planning. London: T. Fisher Wachsmann, W., 1995. Building the wooden house: technique and design, translation by Peter Reuss. Basel: Birkhäuser. Whitlock, R., 1979. Historic Forests of England, Wiltshire: Moonraker Press.

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Interviews, discussions and presentations: daCol, R., 2016. Waugh Thistleton Architects. Interviewed by Sawcer, R., Waugh Thistleton Offices, Shoreditch, 21 January 2016. Host, 2014. Stave Church Information. Interviewed by Sawcer, R., Norske Folkemuseum, Oslo, Norway, 19 September 2014. Ogle, A., 2016. Waugh Thistleton Architects. Interviewed by Sawcer, R., Waugh Thistleton Offices, Shoreditch, 21 January 2016. Owarish, M., 2015. M10 Fire consultancy. Interviewed by Sawcer, R., Queenâ&#x20AC;&#x2122;s College, Cambridge, 23 February 2015. Oxley, M., 2016. Cambridge Centre for Housing & Planning Research. Group Discussion, Faculty of Architecture and History of Art, Cambridge University, 10 May 2016. Fletcher, W. and Randal, J., 2014. Lend Lease. Interviewed by Sawcer, R., Lend Lease Offices, Euston Square, 5 December 2014. Lawrence, A. and Abeysekera, I., 2015. ARUP. Discussions with team at Waugh Thistleton Architects, Waugh Thistleton Offices, Shoreditch, 15 October 2015 Probert, W, 2016. Stora Enso. Email Correspondence, 24 â&#x20AC;&#x201C; 29 February 2016. de Rijke, A., 2015. dRMM. Interviewed by Sawcer, R., Royal College of Art, 24 March 2015. Scalbert, I., 2015. Review of Project. Department of Architecture, University of Cambridge, 20 February 2015. Smith, A., 2014. Hawkins\Brown. Interviewed by Sawcer, R., Banyan Wharf site, London, 15 December 2014. Todd, J., 2014. Architype. Interviewed by Sawcer, R., Architype offices, Borough, 5 December 2014. Toon, S. and Partridge, R., 2015. AKTII. Discussions with team at Waugh Thistleton Architects, Waugh Thistleton Offices, Shoreditch, 12 October 2015. Waugh, A., 2015. Waugh Thistleton Architects. Interviewed by Sawcer, R., Waugh Thistleton Offices, Shoreditch, 20 August 2015. Waugh, A., 2016. Waugh Thistleton Architects. Timber in The City Presentation, Department of Architecture, University of Cambridge, 17 May 2016. Westwood, T., 2016. Waugh Thistleton Architects. Interviewed by Sawcer, R., Waugh Thistleton Offices, Shoreditch, 21 January 2016. White, G. and Skinner, J., 2014. Ramboll. Interviewed by Sawcer, R., Ramboll Offices, Cambridge, 17 November 2014. Wilson, P., 2015b. Timber Design Initiatives Ltd. Presentation to Waugh Thistleton Architects and discussion with Sawcer, R., Waugh Thistleton Offices, Shoreditch, 2 December 2015. Bibliography

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