CARBON COPIES HOUSES TOWERS COMPLEX SHAPES MID-RISE AIRPORTS HOSPITALS/LABS BRIDGES
Andrew Reynolds Ching Yuet Ma Chloe Shang Daniah Basil Abdulazeez Al Mounajim Dario Biscaro Grant Donaldson Hayden Mills Janice Lo Lee Hei Yin Luca Luci Miles Elliott Mir Jetha Xinyi Shen Zhiting Jin Groupwork Royal College of Art
ACKNOWLEDGEMENTS
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CONTENTS 1.0 INTRODUCTION Purpose of research Thornbury Green Site location Site images Masterplan Typologies Focus typologies
HOUSES
2.0 EXISTING CONDITION Existing condition summary Menu of components Structural solution Construction methedology Internal fit-out
10 12 14 16 18 20
24 26 28 30 32
Drawings Plans Section/Elevation
34 36
Detail Drawings Foundation External wall Eave Internal structural wall Internal partition wall
38 40 42 44 46
Images Taylor Wimpey images
48
Embodied carbon calculation Cost analysis
50 51
Existing condition findings
54
3.0 CARBON COPY Alternative proposals summary Menu of components Structural solutions Foundations Insulation types Stone rainscreen Timber windows Stone roof tiles Internal partitions Internal floor finishes
4
8
58 60 62 84 86 92 106 108 110 112
114 116
Detail Drawings Foundation External wall Eave Internal structural wall Internal partition wall
118 120 122 124 126
Images Carbon copy image comparisons
128
Embodied carbon calculation Cost analysis
134 133
Carbon copy comparitive findings
136
140
Internal stone External stone Timber piles
142 146 150
5.0 FINDINGS Final comparitive findings
6.0 CATALOGUE OF MATERIAL COMPONENTS Component Catalogue
HOUSES
4.0 WHAT IF? What if? summary
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Drawings Plans Section/Elevation
156
158
5
6 HOUSES
1.0 INTRODUCTION
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1.0 INTRODUCTION
HOUSES
PURPOSE OF RESEARCH
8
Figure 1.1 Typical suburban house construction
We are in a climate emergency. The construction industry contributes an estimated 40% of total carbon emissions in the UK annually. The UK also has targets to build 300,000 new homes per year by 2025. With these two facts in mind, this research investigates the methods and envirionmental impact of the most commonly built housing typology in the UK: the suburban house. Through a detailed analysis of the existing condition, we propose alternative solutions that are both econimcally viable and radically better for the environment.
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SUBURBAN HOUSE TYPOLOGY
Taylor Wimpey is the UK’s largest house building company, expecting to complete 14,000 homes by the end of 2021. This project uses a typical Taylor Wimpey housing development in the village of Eynsham, Oxfordshire as a research site. Through this research, we have concluded that by changing materials and construction methedology it is possible to build a carbon copy development of that proposed by Taylor Wimpey that is faster. cheaper. greener. HOUSES
COST COMPARISON
150000 100000 50000 0
0
Existing Condition
Stone + Timber Frame
-50000
Stone + CLT
Existing Condition
Stone + CLT
Stone + Timber Frame
-100000
-20000
Large stone
-40000
kgCO2e/m3
20000
40000
Cost per house/£
200000
EMBODIED CARBON COMPARISON
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1.0 INTRODUCTION
THORNBURY GREEN
TAYLOR WIMPEY Taylor Wimpey are the largest house builder in the UK, expecting to complete 14,000 homes in 2021. It is therefore pertinent to investigate how they are building these homes, how carbon intensive they are, how comfortable they are and if they can be built better. WHY THORNBURY GREEN
HOUSES
Thornbury Green is a typical Taylor Wimpey estate, in truth we could have picked any site anywhere in the country as the exact same houses are built from Penzance to Newcastle.
LOCATION Thornbury Green is located on a greenfield site in the village of Eynsham, five miles north west of Oxford. Eynsham is a commuter village for Oxford.
DATE OF CONSTRUCTION Thornbury Green is due for completion in 2021 with half of the homes already built.
CONSTRUCTION MATERIAL/METHODOLOGY
10
The houses all share a common logic no matter the typology. Perimeter concrete blockwork supports softwood timber joists and rafters that span between to make the floors and roof.
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Figure 1.2 Thornbury Green housing development
11
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1.0 INTRODUCTION
SITE LOCATION
EYNSHAM
HOUSES
The site is a greenfield site on the western edge of the village of Eynsham in Oxfordshire, five miles north west of Oxford. The village has a population of 4648.
Figure 1.3 Satellite image of Eynsham clearly marking the Thornbury Green on the western edge
12
Figure 1.4 OS Map
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Eynsham
HOUSES
Oxford
13
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1.0 INTRODUCTION
SITE IMAGES
THORNBURY GREEN
14
HOUSES
The site is a greenfield site on the western edge of the village of Eynsham in Oxfordshire, five miles north west of Oxford. The village has a population of 4648.
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Figure 1.5 Thornbury Green housing development
15
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1.0 INTRODUCTION
MASTERPLAN
SITE INFORMATION Developer Taylor Wimpey Total Homes 160 80 (Phase 1)
HOUSES
Site Area 0.074km2
MASTERPLAN KEY 2 Bedroom: 10
3 Bedroom: 44
4 Bedroom: 86
16
5 Bedroom: 20
Total GIA 20 662.30m2 10 331.15m2 (Phase 1) Total NIA 16 872.94m2 8 436.47m2 (Phase 1)
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Figure 1.6 Thornbury Green masterplan
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1.0 INTRODUCTION
TYPOLOGIES 2 BED
Name: The Canford Total Units: 5 GIA: 64.01m2/Unit 320.05m2/Total NIA: 48.26m2/Unit 241.30m2/Total
HOUSES
3 BED
Name: The Gosford Total Units: 4 GIA: 80.45m2/Unit 321.80m2/Total NIA: 61.77m2/Unit 247.08m2/Total
Name: The Alton G Total Units: 10 GIA: 100.80m2/Unit 1008.00m2 NIA: 79.96m2/Unit 799.60m2/T
4 BED
Name: The Midford Total Units: 8 GIA: 108.70m2/Unit 869.60m2/Totall NIA: 79.25m2/Unit 634.00m2/Total
Name: The Marford Total Units: 28 GIA: 145.30m2/Unit 4068.40m2 NIA: 119.15m2/Unit 3336.20m2
5 BED
18
Name: The Wayford Total Units: 7 GIA: 172.33m2/Unit 1206.31m2/Total NIA: 137.87m2/Unit 965.09m2/Total
Name: The Templeton Total Units: 3 GIA: 223.62m2/Unit 670.86m2/T NIA: 172.32m2/Unit 516.96m2/T
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/Total /Total
2
2
HOUSES
/Total Total
2
Name: The Charlbury Total Units: 8 GIA: 120.68m2/Unit 965.44m2/Total NIA: 90.47m2/Unit 723.26m2/Total
Name: The Manford Total Units: 7 GIA: 128.67m2/Unit 900.69m2/Total NIA: 104.40m2/Unit 730.80m2/Total
Total Total
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1.0 INTRODUCTION
FOCUS TYPOLOGIES
HOUSES
In order to focus the study, we have selected the two most frequent typologies in the development to analyse in further depth. These include a three bedroom semi-detached house and a four bedroom detached house.
Figure 1.7 The Alton G
3 BED: THE ALTON G
Total units 10
Bedrooms 3
GIA 100.80m2/Unit
Envelope Single skin brick/ Recon stone lintels/ Triple glazing
20
NIA 79.96m2/Unit
Glazed area 7.80m2/Unit
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Figure 1.8 The Marford
4 BED: THE MARFORD
Total units 28
Bedrooms 4
GIA 128.67m2/Unit
Envelope Stone veneer / Recon stone lintels/ Triple glazing
NIA 104.40m2/Unit
Glazed area 7.80m2/Unit 21
22 HOUSES
2.0 EXISTING CONDITION
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2.0 EXISTING CONDITION
SUMMARY
SIMPLE BUILDINGS WITH STANDARD DETAILS Taylor Wimpey’s business model means they buy designs of houses much like you would buy a car or a jumper, they buy the rights and then they can build them wherever they like. What this means in practice is they have a set of standard details which are used all over the country that do not respond to local conditions and are completely devoid of any true character or ambition.
We have analysed the standard details to see what we can learn from how Taylow Wimpey build, where the most embodied carbon is and how we can do it better.
COST/HOUSE
Cost per house/£
0
20000 0
kgCO2e/m3
40000
100000
EMBODIED CARBON/HOUSE
Existing Condition
24
50000
HOUSES
Thornbury Green is a new build development on green build site that is a net carbon emitter so not only is the creation of these homes adding carbon to our atmosphere, they are reducing biodiversity. Secondly they are poorly insulated meaning that they are expensive to run and cost further carbon byway of heating and cooling them.
Existing Condition
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Figure 2.1 Thornbury Green housing development
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2.0 EXISTING CONDITION
MENU OF COMPONENTS
FOCUS ON WALL TYPE We have focussed our analysis primarily on wall type because in such simple buildings as these, this is where carbon can be reduced most effectively.
HOUSES
C
B
A
D
Figure 2.2 3 Bedroom semi-detached house
A
D
Foundation
Internal partition wall
B
E
Wall-floor connection
Internal structural wall
C
26
Eave/Dormer
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C
B
A
E
Figure 2.3 4 Bedroom detatched house
27
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2.0 EXISTING CONDITION
STRUCTURAL SOLUTION
SAME STRATEGY NO MATTER THE TYPOLOGY
HOUSES
All houses share a common structural strategy no matter the typology, this includes: poured reinforced concrete foundations, perimeter aircrete blockwork, concrete beam and block slab and internal softwood timber joists and rafters. The timber joists span perpendicular to the front elevation in the 3 bed house and parallel to it in the 4 bed house with an additional internal structural wall.
28
Figure 1.1 Thornbury Green housing development
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3 BED
HOUSES
4 BED
29
Softwood timber Concrete block/Reinforced concrete
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2.0 EXISTING CONDITION
CONSTRUCTION METHODOLOGY
ON SITE LABOUR INTENSIVE None of the elements used are prefabricated off site. Footings, foundations, blockwork, the timber joists and roofing slates are all constructed on site by hand; this means that the time spent on site is long and busy. An average Taylor Wimpey site, such as Thornbury Green, has one hundred people working on it at a time.
FOOTINGS
HOUSES
Footings are 150mm reinforced concrete poured in situ.
FOUNDATIONS Foundations are constructed as a twin layer of aircrete blockwork with 100mm insulation in between.
SLAB
30
The slab is quickly constructed as a concrete beam and block floor. This sits on the foundation at 150mm above the ground with a void in between.
Structural walls are made with external aircrete blockwork.
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STRUCTURAL WALLS
RAINSCREEN
HOUSES
The rainscreens are either a single skin of self supporting brick or stone slates which are glued to a second layer of aircrete blockwork. The choice of rainscreen is typology dependant.
TIMBER JOISTS Softwood timber joists are cut and secured together with nail plates on site.
INSULATION Glass mineral wool is sprayed into the cavity after the walls are built. This method is quick but can result in an uneven result.
31
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2.0 EXISTING CONDITION
INTERNAL FIT-OUT
FINISH HEAVY
32
HOUSES
The basic construction components mean that many layers of finish are required in order to make the homes comfortably habitable. This includes the use of plasterboard and paint, wallpaper or tiles on walls, plasterboard and paint on soffits and carpet or porcelain tiles on floors. All of these finishes are areas to target to reduce the overall embodied carbon of each house.
Ceramic tiling Carpet Paint Wallpaper Softwood radiator cover Softwood skirting
KITCHENS
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HALLWAYS
Ceramic tiling Paint Chipboard/melamine surfaces Softwood skirtings Curtains
LIVING SPACES HOUSES
Carpet Paint Wallpaper Softwood skirting
BEDROOMS Carpet Paint Wallpaper Softwood skirting Curtains
BATHROOM Ceramic tiling Paint Plastic bathrub Porcelain loo and sink
33
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2.0 EXISTING CONDITION
PLAN
HOUSES
3 BED
4 BED
34
0m
1
2
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2.0 EXISTING CONDITION
SECTION/ELEVATION
HOUSES
3 BED
36
0m
1
2
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2.0 EXISTING CONDITION
FOUNDATION DETAIL 3 BED
2
1
HOUSES
3
5 4
VOID
6
1
38
2
Wall Brick 100mm glass mineral wool insulation Wall cavity tie Concrete blockwork DPM Wall finish 12mm plasterboard
3
Paint 12x100mm softwood skirting
4
Slab Concrete beam and block floor system
Floor finish Carpet Underlay 75mm concrete screed 75mm rigid insulation DPM
5
Foundation wall Concrete block 100mm EPS insulation
6
Footing 150mm reinforced concrete
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4 BED
2
1
3
HOUSES
5 4
VOID
6
1
2
Wall Limestone veneer Concrete blockwork 100mm glass mineral wool insulation Wall cavity tie DPM Wall finish 12mm plasterboard
3
Paint 12x100mm softwood skirting
4
Slab Concrete beam and block floor system
Floor finish Carpet Underlay 75mm concrete screed 75mm rigid insulation DPM
5
Foundation wall Concrete block 100mm EPS insulation
6
Footing 150mm reinforced concrete
39
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2.0 EXISTING CONDITION
EXTERNAL WALL DETAIL 3 BED
HOUSES
1
2
3
4
1
40
2
Wall finish 12mm plasterboard Paint 12x100mm softwood skirting Floor finish Carpet Underlay 75mm concrete screed
75mm rigid insulation DPM 3
Slab Concrete beam and block floor system
4
Wall 100mm concrete block 100mm glass mineral
wool insulation Wall cavity ties 5
Footing 150mm reinforced concrete
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4 BED
1
HOUSES
2
3
4
1
2
Wall finish 12mm plasterboard Paint 12x100mm softwood skirting Floor finish Carpet Underlay 75mm concrete screed
75mm rigid insulation DPM 3
Slab Concrete beam and block floor system
4
Wall 100mm concrete block 100mm glass mineral
wool insulation Wall cavity ties 5
Footing 150mm reinforced concrete
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2.0 EXISTING CONDITION
EAVE DETAIL 3 BED AND 4 BED
HOUSES
1
2 4
3
5
1
42
2
Roof build-up Cement fibre tiles Softwood timber batten Waterproof membrane Softwood timber rafters Mineral wool insulation Gutter Plastic gutter Underlay
3
Fascia Plastic fascia board Softwood timber batten
4
Wall 100mm concrete block 12mm plasterboard Paint
5
Soffit 100mm glass mineral wool insulation 12mm plasterboard Paint
6
Window uPVC triple glazed window Steel lintel angle
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2.0 EXISTING CONDITION
INTERNAL STRUCTURAL WALL DETAIL 3 BED (PARTY WALL)
1
HOUSES
2
VOID
VOID
3 4
5
1
44
2
Wall finish 12mm plasterboard Paint 12x100mm softwood skirting Floor finish Carpet Underlay 75mm concrete screed
75mm rigid insulation DPM 3
Slab Concrete beam and block floor system
4
Wall 100mm concrete block 100mm glass mineral
wool insulation Wall cavity ties 5
Footing 150mm reinforced concrete
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4 BED
1
2
HOUSES
VOID
VOID
3 4
5
1
2
Wall finish 12mm plasterboard Paint 12x100mm softwood skirting Floor finish Carpet Underlay 75mm concrete screed
75mm rigid insulation DPM 3
Slab Concrete beam and block floor system
4
Wall 100mm concrete block 100mm glass mineral
wool insulation Wall cavity ties 5
Footing 150mm reinforced concrete
45
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2.0 EXISTING CONDITION
INTERNAL PARTITION WALL DETAIL 3 BED AND 4 BED
1
HOUSES
2
VOID
3
1
46
2
Wall 90mm metsec frame 12mm plasterboard Paint 12x100mm softwood skirting Floor finish Carpet Underlay
75mm rigid insulation DPM 3
Slab Concrete beam and block floor system
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2.0 EXISTING CONDITION
IMAGES
48
HOUSES
3 BED
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4 BED
HOUSES
49
HOUSES
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2.0 EXISTING CONDITION
EMBODIED CARBON
MATERIAL
ELEMENT
VOLUME M3
EMBODIED CARBON KGCO2E
Concrete
Strip foundation
3
1597
Blockwork
Walls
45
12,799
Limestone
Veneer
7
1298
Softwood
Stud partitions
2
-1,139
Softwood
Floor joists
n/a
-351
Concrete
Beam and block floor
11
3119
Concrete
Screed
2
1832
Plywood
Floor
2
-622
Plasterboard
Internal lining
6
1567
Fibre cement
Roof tiles
3
949
Softwood
Roof trusses
4
-2291
Mineral wool
Insulation
47
698
Glass
Windows
<1
380
Limestone
Sills and lintels
<1
74
50
TOTAL/HOUSE
19,737
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COST ANALYSIS
ELEMENT
QUANTITY M2
COST £
Concrete
Strip foundation
3
239
Blockwork
Walls
45
24,352
Limestone
Veneer
7
2061
Softwood
Stud partitions
2
2840
Softwood
Floor joists
176
1753
Concrete
Beam and block floor
11
8765
Concrete
Screed
2
509
Plywood
Floor
2
1525
Plasterboard
Internal lining
6
9194
Fibre cement
Roof tiles
3
216
Softwood
Roof trusses
4
1028
Mineral wool
Insulation
47
17,317
Glass
Windows
<1
6750
Limestone
Sills and lintels
<1
117
TOTAL/HOUSE
HOUSES
MATERIAL
76,665
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2.0 EXISTING CONDITION
FINDINGS
CARBON INTENSIVE SIMPLE BUILDINGS The analysis of the existing condition has showed us that while these are incredibly simple buildings they are very carbon intensive. The homes are cheap to build but expensive to run because their insulation is so poor. Finally they are not site specific and therefore do not take into account local geology meaning that the standard Taylor Wimpey details may not be sufficient - again putting the onus on repair and maitenance by the home owner over due dilligance and quality from the start.
COST/HOUSE
Cost per house/£
0
20000 0
kgCO2e/m3
Existing Condition
52
50000
100000
EMBODIED CARBON/HOUSE 40000
HOUSES
The foundations, structure and many layers of finish are the three principal components we must focus on to propose a carbon negative carbon copy.
Existing Condition
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54 HOUSES
3.0 CARBON COPY
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3.0 CARBON COPY
SUMMARY
GREENER, CHEAPER, FASTER In order to reduce the overall emboided carbon, we bagan by changing the most carbon intensive elements of the existing structural solution - the reinforced concrete and concrete blocks. Why use concrete when you can use the inherient strength of stone in a carbon negative and more efficient process?
Our investigations show that with extended thinking about material qualities, construction methods and flow chains that it is possible to build carbon copies of the Taylor Wimpey design that are both economically viable and provably better for the environment. COST COMPARISON
-40000
56
150000 100000 50000 0
0
Existing Condition
Large stone
-50000
-20000
kgCO2e/m3
20000
40000
Cost per house/£
40000
40000
200000
EMBODIED CARBON COMPARISON
Existing Condition
Stone + CLT
Stone + Timber Frame
-100000
HOUSES
Above the foundations, we have investigated two all timber options, one timber frame and one CLT to assess which method is the greenest, fastest and cheapest. Timber has been selected as the structural solution due to the truly renewable quality of trees. Within our assessment we have looked equally at material sourcing, processing, transportation, construction, cost and resultant occupant comfort for both options in order to come to a valid conclusion of which method is best: stone with a timber frame.
Stone + CLT
Stone + Timber Frame
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Figure 3.1 4 Bedroom carbon copy
168%
24%
EMBODIED CARBON
PROJECT COST
57
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3.0 CARBON COPY
MENU OF COMPONENTS
CARBON COPY COMPONENTS All the components analysed in the existing condition have been redrawn according to our research to show how our carbon copy how that is cheaper, greener and faster can be built.
HOUSES
C
B
A
D
Figure 3.2 3 Bedroom carbon copy
A
D
Foundation
Internal partition wall
B
E
Wall-floor connection
Internal structural wall
C
58
Eave/Dormer
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C
B
A
E Figure 3.3 4 Bedroom carbon copy
59
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3.0 CARBON COPY
STRUCTURAL SOLUTION A - TIMBER FRAME
TIMBER I-JOISTS External timber I-joist frame. The internal plan is kept structurally free to allow for future flexibility. This method can be built by hand using similar construction methods as Taylor Wimpey’s current model. Time on site is longer than CLT but overall material quantity is far less. EMBODIED CARBON
HOUSES
-703kgCO2e/m3
60
Figure 3.4 Timber I-joist structural iso
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Figure 3.5 Timber I-joist construction
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3.0 CARBON COPY
FABRICATION A - TIMBER FRAME
TIMBER I-JOISTS
HOUSES
Traditional timber framing uses simple softwood studs to form the structural frame. We are using the timber frame system used in passivhaus buildings where timber I-joists comprised of two small softwood timber sections connected and stiffened by a 12mm OSB sheet. This allows us to create a deep insulation cavity and achieve a low u-value with the most minimal amount of material possible. OSB must undergo a secondary process which of course increases its carbon footprint but it is still predominately carbon sequestering timber and makes use of waste material so is inherintly sustainable. The largest manufacturer of timber I-joists in Europe is located in Scotland. Joists are manufactured and cut to length in the factory therefore reducing waste and time spent on site.
62
Figure 3.6 Timber I-joist fabrication at James Jones in Scotland
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FABRICATION PROCESS
HOUSES
COMPONENTS Softwood timber - 100% OSB - softwood timber strands 95% - resin and wax 5%
Figure 3.7 Timber I-joist
63
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3.0 CARBON COPY
TRANSPORTATION A - TIMBER FRAME
EFFICIENT STACKING Transporting timber I beams is incredibly efficient; in each lorry, enough timber for three houses can fit in. This efficiency coupled with the short transport distance from Scotland means the embodied carbon on bringing it to site is very low - nearly seven times as less than CLT.
HOUSES
n.b. Embodied carbon has been calculated assuming lorries are fully loaded on delivery to site and empty upon return.
64
Figure 3.8 Timber I-joist transportation
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600 KM
HOUSES
Figure 3,9 Option A transport route
3 BUILDINGS/LORRY
48 JOURNEYS 59.6 TONNES CO2E Figure 3.10 Option A transport analysis
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3.0 CARBON COPY
CONSTRUCTION A - TIMBER FRAME
RELATIVELY LONG ON SITE COMPARED TO CLT Constructing a timber frame house is not dificult nor is it long in comparison to the masonry walls of the existing condition. Members come precut from the factory so there is no on site cutting required. Pieces are nail gunned together before being panelled and filled with insulation.
HOUSES
In comparison to CLT, this is a labour intensive and time consuming method.
66
Figure 3.11 Timber I-joist construction
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3.0 CARBON COPY
FINISH A - TIMBER FRAME
TIMBER PANELLING REQUIRED
HOUSES
Timber panels must be fixed to the inside of the insulated timber frame to make the walls of the homes, this of course is an extra source of material and cost associated with this method. Instead of using the current system of plasterboard and paint or wallpaper however, veneered plywood panelling can be used with the higher cost compared to plasterboard offset by the lack of final finishes. Time on site and labour costs are reduced by not requiring extra decoration.
68
Figure 3.13 Veneered plywood wall panelling
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1
2
HOUSES
Figure 3.14 Timber I-joist component iso
1
Limestone wall 75mm limestone Waterproof membrane 15mm Plywood 300mm insulation
2
Timber frame 300mm Timber I-joist 12mm veneered plywood panelling
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3.0 CARBON COPY
STRUCTURAL SOLUTION B - CLT
PREFABRICATION External CLT frame. The internal plan is kept structurally free to allow for future flexibility. This method is prefabricated off-site and brought to site flat pack therefore minimising on-site time and transportation emissions. This is quick and simple to construct but overall the material quanitity is higher than a timber frame as is the required timber quality.
EMBODIED CARBON
HOUSES
-841kgCO2e/m3
70
Figure 3.15 CLT structural iso
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Figure 3.16 CLT construction
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3.0 CARBON COPY
FABRICATION B - CLT
FINISH READY IN THE FACTORY
HOUSES
CLT is comprised of timber lengths being glued together into panels. This process increases the strength of the timber and means that wall panels can be made to the exact dimensions required with all openings precut in the factory. Machine precision means that time reduces waste and time on site. The massive nature of CLT panels means that technically a lot of carbon is sequestered per house houwever the amount of material used is far greater than in timber frame. From an environmental and cost perspective therefore, CLT is less appropriate for this typology.
72
Figure 3.17 CLT fabrication in the factory
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FABRICATION PROCESS
HOUSES
COMPONENTS CLT - Softwood timber >99% - Adhesive <1%
Figure 3.18 CLT
73
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TRANSPORTATION B - CLT
FLAT PACK CLT panels are transported as individual flat pack panels to site for assembly. Transporting panels over completed homes saves carbon because the amount of wasted space on each truck is reduced dramatically so less lorry loads are required. Even so, each building (single detached house or two semi-detached houses) will require its own lorry to transport. Currently there are no CLT manufactures in the UK so all panels will have to come from Austria meaning transporting CLT uses nearly seven times as much carbon compared to timber frame.
HOUSES
n.b. Embodied carbon has been calculated assuming lorries are fully loaded on delivery to site and empty upon return.
74
Figure 3.19 CLT transportation
ROYAL COLLEGE OF ART ADS5
1520 KM
HOUSES
Figure 3.20 Option B transport route
1 BUILDING/LORRY
142 JOURNEYS 404.7 TONNES CO2E Figure 3.21 Option B transport analysis
75
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3.0 CARBON COPY
CONSTRUCTION B - CLT
QUICK CONSTRUCTION
HOUSES
There are 42 pieces per house, all of which come precut and drilled so simply need to be craned into postion when they arrive on site. A house can be erected in more or less a day.
76
Figure 3.22 CLT construction
ROYAL COLLEGE OF ART ADS5
HOUSES
77
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3.0 CARBON COPY
FINISH B - CLT
NO EXTRA FINISHES
HOUSES
CLT panels require not supplementary finishes such as paint or wallpaper because of the natural beauty of the timber. Not only is this better for the environment and cost but it is also better for occupant health with scientific studies proving the wellbeing benefits of living in timber homes.
78
Figure 3.24 Barrett’s Grove, Groupwork
ROYAL COLLEGE OF ART ADS5
1
2
HOUSES
Figure 3.25 CLT component iso
1
Limestone wall 75mm limestone Waterproof membrane 15mm Plywood 300mm insulation
2
CLT 100mm CLT fire coated panel
79
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STRUCTURAL FINDINGS
OPTION A - TIMBER FRAME Timber frame is the best option for these houses. Technically they do not have such a high negative embodied carbon as CLT but this is because the material needed is so much less. The most sustainable thing is to leaves trees in the ground so following embodied carbon figures alone is misguided - timber frame is still negative. Secondly the cost of timber frame is dramatically cheaper as is the embodied carbon of transporting it to site. Time on site may be slightly longer than CLT but any costs associated with this are fully offset by the material price.
150000
Timber Frame
80
100000 75000 25000 0
Cost per house/£
-20000 -50000 -60000
-40000
-30000
kgCO2e/m3
-10000
125000
0
CLT
COST COMPARISON
50000
HOUSES
EMBODIED CARBON COMPARISON
CLT
Timber Frame
ROYAL COLLEGE OF ART ADS5 HOUSES
Figure 3.26 Timber I-joist construction iso
81
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FOUNDATIONS
CLAY SOIL The site sits on clay soil. Clay is succeptible to heaving and settling, this is where the ground water content chanegs and the earth can increase by 150mm (heave) or decrease by 150mm (settle), both are detrimental to the structure of a building. In order to limit it’s effects, deep pads are more appropriate than the existing condition of shallow strip foundation. The void between the earth and the underside of the floor must also increase to 300mm to withstand the potential +/-150mm differential.
HOUSES
2m deep limestone pad foundation limit the potential damage from the soil and also drastically reduce embodied carbon. The large cost increase could be thought to be offset over the lifespan of each building as it is less likely to require maintenence.
EYNSHAM
Figure 3.27 Geology map showing the clay soils of the Cotswolds
Clay soil
COST COMPARISON
1200 400 0
0
Concrete strip
82
800
Cost per house/£
800 400
kgCO2e/m3
1200
1600
1600
EMBODIED CARBON COMPARISON
Limestone pads
Concrete strip
Limestone pads
150 750
312x35000x150mm reinforced concrete
ROYAL COLLEGE OF ART ADS5
EXISTING CONCRETE STRIP
PROPOSED STONE PADS HOUSES
2000
300
600x600x300mm limestone
2700
2700
2700
HEAVING
SETTLING
Increase in soil water level +150mm
Decrease in soil water level -150mm
83
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INSULATION TYPES
SAME STRATEGY NO MATTER THE TYPOLOGY
HOUSES
The current Taylor Wimpey standard wall build-up achieves a u-value of 0.25W/m2K, using 100mm of blown glass mineral wool insulation. Not only does this mean the houses are not sufficiently warm on their own and therefore rely on expensive, usually carbon intensive heating but the embodied carbon on the material itself is incredibly high at +1.86kgCO2e/ kg. We have investigated several alternative insulation materials, assessing their thermal conductivity, embodied carbon and u-value achievement at different thicknesses using different wall build-ups. We are aiming to improve the u-value of these homes to passivhaus standard 0.15W/m2K while simulataneously reducing the environmental impact of constructing with our chosen insulation. Passivhaus standard has been chosen as a target because its performance can be quantifiably proved excellent and will not result in excessively thick walls. Hemp Batts provide a good thermal conductivity and are carbon negative. EXISTING
U-VALUE 0.25W/m2K
PROPOSED
84
TARGET U-VALUE 0.15W/m2K
Mineral
Image: Knauf Insulation
0.034 W/mK Embodied Carbon: Embodied Carbon: +1.12 kgCO2e/kg +0.63 kgCO2e/kg Embodied Carbon: Thermal Conductivity: GLASS MINERAL WOOL kgCO2e/kg Embodied carbon +1.86 Thermal Conductivity: +1.86kgCO e/kg 0.035-0.038 W/mK Embodied Carbon: 0.038 W/mK Thermal conductivity Thermal Conductivity: +0.98 kgCO2e/kg 0.034W/m k Embodied Carbon: Carbon: 0.034 W/mK +0.63 kgCO2e/kg kgCO2e/kg +1.12 MINERAL WOOL Embodied carbon Thermal Conductivity: +1.12kgCO e/kg Thermal conductivity 0.037 W/mK Conductivity: Thermal Conductivity:
al edWool Mineral paper
Wood al Wool led paper
2
2
0.035W/m2k
Image: Knauf Insulation
2
2
Image: STEICO Protect Dry Image: Image:Architects RockwoolJournal
2
2
2
Image: STEICO Protect Dry Image: Wynnes Image: Architects Journal Image: Rockwool
2
2
Image: Celtic Sustainables Image: Wynnes Image: STEICO Protect Dry
2
Image: Architects Journal
2
2
Image: Celtic Sustainables Image: Black Mountain Image: Wynnes Image: STEICO Protect Dry
2
2
0.039 W/mK Thermal Conductivity: Conductivity: Embodied Carbon: Thermal 0.039W/mK W/mK Unknown 0.18
Image: Black Mountain Image: Celtic Sustainables
Image: Wynnes
85
Batts ps tedWool Lime r Batts
Image: Rockwool Image: Architects Journal
HOUSES
ps tedWool Lime Bales r
Image: Knauf Insulation
2
0.038 W/mK W/mK 0.035-0.038 Embodied Carbon: Embodied Carbon: RIGID WOOD FIBRE Embodied carbon +0.98 kgCO2e/kg +0.98kgCO e/kg +0.01 kgCO2e/kg Embodied Carbon: Carbon: Thermal conductivity Embodied 0.037W/m k +0.63 kgCO2e/kg kgCO2e/kg Thermal Conductivity: +1.12 Thermal Conductivity: 0.037 W/mK Embodied Carbon: 0.048 W/mK INSULATED LIME PLASTER Conductivity: Embodied carbon Thermal Thermal Conductivity: +0.78 kgCO2e/kg +0.78kgCO e/kg Embodied Carbon: Embodied Carbon: 0.038 W/mK Thermal conductivity 0.035-0.038 W/mK +0.01 kgCO2e/kg kgCO2e/kg 0.018W/m k +0.98 Embodied Carbon: Thermal Conductivity: +0.63 kgCO2e/kg 0.18 W/mK Thermal Conductivity: Thermal Conductivity: RECYCLED NEWSPAPER 0.048 W/mK W/mK Embodied carbon 0.037 +0.63kgCO e/kg Embodied Carbon: Thermal Conductivity: Embodied Carbon: Thermal conductivity +0.78W/mK kgCO2e/kg 0.038W/m k 0.038 -1.28 kgCO2e/kg Embodied Carbon: Carbon: Embodied STRAW BALES Embodied carbon +0.01 kgCO2e/kg kgCO2e/kg Thermal Conductivity: +0.98 +0.01kgCO e/kg Thermal Conductivity: Thermal conductivity 0.18 W/mK 0.048W/m k 0.039 W/mK Thermal Conductivity: Thermal Conductivity: Embodied Carbon: Embodied Carbon: 0.048 W/mK 0.037 W/mK -1.28 kgCO2e/kg SHEEP’S WOOL+0.78 kgCO2e/kg Embodied carbon +0.07kgCO e/kg Embodied Carbon: Thermal conductivity Thermal Conductivity: +0.01 kgCO2e/kg 0.039W/m k Thermal Conductivity: 0.039 W/mK 0.18 W/mK Thermal Conductivity: HEMP BATTS Embodied Carbon: Embodied carbon -0.63kgCO e/kg 0.048 W/mK Unknown Thermal conductivity Embodied Carbon: Carbon: Embodied 0.039W/m k -1.28 kgCO2e/kg +0.78 kgCO2e/kg Thermal Conductivity:
Wood Bales led al Wool paper ted Lime Wood rBales ed paper ted Lime s Wool rBales Wood
Image: Rockwool
ROYAL COLLEGE OF ART ADS5
n Types
+1.12 kgCO2e/kg Embodied Carbon: +1.86 kgCO2e/kg Thermal Conductivity: 0.035-0.038 W/mK Thermal Conductivity:
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3.0 CARBON COPY
WALL THICKNESS STUDIES TARGET: 0.15W/M2K (PASSIVHAUS) Investigating how thick wall build-ups will be with specific insulation thicknesses and the u-values that can be achieved. Numbers in red are equal to or less than the required 0.15W/M2K Passivhaus standard. 312
312
MATERIAL
HOUSES
TW STANDARD
312
312
312
387
387
387
175MM 387
387
231
306
306
231
231
306
306
Glass mineral wool Recycled newspaper Mineral wool Wood fibre Sheep’s wool Hemp231 Straw bale
0.25 0.27 0.27 0.26 0.27 0.27 0.31
Glass mineral wool 0.16 Recycled newspaper 0.17 Mineral wool 0.16 Wood fibre 0.16 Sheep’s wool 0.17 306 Hemp 306 0.18 Straw bale 0.21
350
350
425
425
350
350
425
425
302
350
Glass mineral wool Recycled newspaper Mineral wool Wood fibre Sheep’s wool Hemp 302 Straw bale
0.29 0.32 0.32 0.31 0.32 0.32 0.38
425
425
Glass mineral wool Recycled newspaper Mineral wool Wood fibre Sheep’s wool Hemp 377 Straw bale
0.18 0.18 0.18 0.19 0.20 377 0.20 0.24
302
302
377
377
302
302
377
377
Glass mineral wool Recycled newspaper Mineral wool Wood fibre Sheep’s wool Hemp Straw bale
86
387
231
350
STONE + TIMBER FRAME
INSULATION THICKNESS 100MM (TW STANDARD)
231
STONE + CLT
312
0.31 0.34 0.34 0.34 0.35 0.35 0.41
Glass mineral wool Recycled newspaper Mineral wool Wood fibre Sheep’s wool Hemp Straw bale
0.20 0.22 0.20 0.21 0.22 0.22 0.26
462
462
537
537
537
612
612
612
462
462
462
537
537
537
612
612
612
250MM 387
387
325MM
462
462
400MM
462
537
537
537
612
381
381
381
457
457
457
531
531
531
381
381
381
457
457
457
531
531
531
0.12 0.13 0.12 0.12 0.13 0.13 0.16
Glass mineral wool Recycled newspaper Mineral wool Wood fibre Sheep’s wool 381 381 Hemp Straw bale
0.09 0.10 0.10 0.10 0.09 457 0.09 0.13
Glass mineral wool Recycled newspaper Mineral wool Wood fibre Sheep’s wool457 Hemp Straw bale
0.08 0.09 0.08 0.08 0.09 457 0.09 0.11
531
500
500
500
575
575
575
650
650
650
500
500
500
575
575
575
650
650
650
425
452
452
425
452
377
500
Glass mineral wool Recycled newspaper Mineral wool Wood fibre Sheep’s wool 452 452 Hemp Straw bale
377
0.13 0.14 0.13 0.14 0.14 0.14 0.17
452
527
452
Glass mineral wool Recycled newspaper Mineral wool Wood fibre Sheep’s wool Hemp Straw bale
500
452
0.17 0.14 0.16 0.15 0.16 0.14 0.20
500
Glass mineral wool Recycled newspaper Mineral wool Wood fibre Sheep’s wool 527Hemp 527 Straw bale
527
452
Glass mineral wool Recycled newspaper Mineral wool Wood fibre Sheep’s wool Hemp Straw bale
575
0.10 0.11 0.10 0.11 0.11 527 0.11 0.14
527
527
0.14 0.11 0.13 0.12 0.12 0.13 0.16
575
Glass mineral wool Recycled newspaper Mineral wool Wood fibre Sheep’s wool 602 Hemp Straw bale
0.08 0.09 0.08 0.09 0.09 0.09 0.11
575
602
527
Glass mineral wool Recycled newspaper Mineral wool Wood fibre Sheep’s wool Hemp Straw bale
527
612
HOUSES
306
Glass mineral wool Recycled newspaper Mineral wool Wood fibre Sheep’s wool 306 381 Hemp Straw bale
ROYAL COLLEGE OF ART ADS5
462
650
602
602
602
602
531
650
602
602
0.11 0.09 0.10 0.10 0.10 0.11 0.13
87
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3.0 CARBON COPY
WALL THICKNESS NEIGHBOURHOOD STUDY
EXTEND BACKWARDS, NOT SIDEWAYS Our insulation studies have shown that we must increase the overall wall build-up to a minimum of 452mm. Using a timber frame reduces the overall build-up by 48mm compared to CLT for equivalent u-values.
HOUSES
Increasing wall build-up will of course impinge on NIA, therefore we have studied whether it is possible to expand out in all directions or if we must keep the same external width as is currently planned and increase the depth of the buildings. It has been concluded that house width cannot be increased with the existing masterplan (which we are keeping the same) but there is space to extend back into the large private garden of each house. Therefore we are elongating the plan of each house in order to accomdate the increase in wall build-up without reducing NIA.
88
Figure 3.28 Each house has a large private garden that can be utilised slightly to accept the improved thicker wallls
9450
ROYAL COLLEGE OF ART ADS5
EXISTING CONDITION
NIA 3B: 79.96m2 NIA 4B: 119.15m2
OFFSETTING EQUALLY OUT - TOO TIGHT FOR DRIVEWAYS
HOUSES
9750
NIA 3B: 79.96m2 NIA 4B: 119.15m2
EXTENDING BACK
100050
NIA 3B: 79.96m2 NIA 4B: 119.15m2
89
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3.0 CARBON COPY
STONE RAINSCREEN
WHY STONE?
HOUSES
Oolitic limestone is vernacular to the Cotswolds region, it has been quarried and built with for centuries. Not only is limestone a contextual choice but also a clear environmental choice as stone has 35% of the carbon emissions of brick. Stone is quarried, minimally processed and brought to site. Concrete blocks or bricks must be quarried, crushed, mixed, fired and then only after all that brought to site. The following investigation outlines how we detail the stone and what effects this has on appearance and construction metheodology as well as carbon emissions.
90
Figure 3.29 Tyoical Cotswolds cottage
ROYAL COLLEGE OF ART ADS5
800
STONE QUARRYING
400 200
CONCRETE BLOCK MAKING
Stone
Brick
Concrete block
Figure 3.30 Comparitive embodied carbon of different rainscreen materials
HOUSES
0
kgCO2e/m3
600
BRICK FIRING
Figure 3.31 Geology map showing the band of oolitic limestone that runs through the Cotswolds
91
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3.0 CARBON COPY
HAND LIFTABLE STONES
SAME CONSTRUCTION METHEDOLOGY AS EXISTING Currently Taylor Wimpey use bricks or stone slips constructed by hand to form their rainscreen facades in front of the structural concrete block walls which are also built by bricklayers. This test explores keeping the same construction methedology but replacing brick/concrete blocks with self supporting limetstone blocks. Limestone has a density of 2400kg/m3. We have used this to get the dimensions of a limestone block that weighs no more than 19kg and is 125mm deep.
HOUSES
EXISTING CONDITION
BRICK
CONCRETE BLOCK
112.5x215x65mm 2.75kg
440x215x100mm 19kg
LIMESTONE
LIMESTONE BLOCK
92
400x200x125mm 19.2kg
ROYAL COLLEGE OF ART ADS5
EMBODIED CARBON/HOUSE Stone thickness: 125mm Stone volume: 25.6m3 Carbon: 4663kg
HOUSES
Figure 3.32 Liftable stone facade
93
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3.0 CARBON COPY
SAFE STONE BANDING
EXPRESSION WITHIN THE FACADE The Health and Safety England guidance on safe lifiting limits in the workplace shows the amount of weight a person can lift by hand at which height they can lift it. Using this, we can size stones accordingly in bands and express the mode of construction through the facade so the simple stone wall starts to tell a tale.
410
HOUSES
410 410
94
410
19.2kg
9.6kg
200x200x125mm
400x200x125mm
500x200x125mm
2090
410
9.6kg
ROYAL COLLEGE OF ART ADS5
EMBODIED CARBON/HOUSE Stone thickness: 125mm Stone volume: 25.6m3 Carbon: 4663kg
HOUSES
Figure 3.33 Liftable stone banding facade
95
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3.0 CARBON COPY
LARGE STONES
40% LESS STONE REQUIRED If a crane is used, the stone facade be made of large sections that act as rainscreen and lintel all in one. Large stones retain the innate structural stability of the stone therefore the thickness of stones slim from 125mm to just 75mm, reducing the material quantity and cost by 40%. The speed of construction compared to a hand built facade will reduce time on site further reducing costs.
HOUSES
Large stones are sized at a maximum of 1000x2000mm so they are not too brittle in transit. This means that they can still be used efficiently to create window openings so extra lintels are not required - further reducing material, cost and carbon.
96
Figure 3.34 Lyon Housing, Gilles Perraudin
ROYAL COLLEGE OF ART ADS5
EMBODIED CARBON/HOUSE Stone thickness: 75mm Stone volume: 16m3 Carbon: 2914kg
HOUSES
Figure 3.34 Large stone facade
97
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3.0 CARBON COPY
LARGE STONES INTEGRATED LINTELS + PORCH FASTER, GREENER The existing condition homes currently have small porch canopies built from painted timber, composite concrete roof tiles and lead. Additionally, reconstituted stone lintels sit above each window.
HOUSES
Using large stones enables us to integrate lintels and a porch canopy into the facade, minimising time on site, reducing material and reducing carbon.
98
Figure 1.1 Thornbury Green housing development
ROYAL COLLEGE OF ART ADS5
Figure 1.1 Thornbury Green housing development
HOUSES
Figure 3.35 Integrated lintels and porch stone
99
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3.0 CARBON COPY
STONE SLIPS
MUCH MORE CARBON INTENSIVE
HOUSES
The exisitng methedology for Taylor Wimpey stone rainscreens is to use stone slips. Taylor Wimpey glue their slips to a layer of concrete blockwork behind but as we have estabalished that a timber frame building is far less carbon intensive, we must use a secondary structure of galvanised steel for slips to hang from. Such a system has nealy 4 times the embodied carbon as liftable self supporting stone and 6.5 times the embodied carbon of large self supporting stone.
100
Figure 1.1 Thornbury Green housing development
ROYAL COLLEGE OF ART ADS5
EMBODIED CARBON/HOUSE Stone slip volume: 10mm Stone slip volume: 6.5m3 Stone slip carbon: 1298kg Galvanised steel secondary structure volume: 1m3 Galvanised steel secondary structure carbon: 16882kg Total carbon: 18,180kg
HOUSES
Figure 3.36 Stone slip facade
101
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3.0 CARBON COPY
STONE RAINSCREEN FINDINGS
LARGE STONES
Figure 3,37 Comparitive rainscreen embodied carbon per house
12,000 0
4000
8000
kgCO2e/m3
16,000
HOUSES
20,000
Our studies have shown that using large stones has nearly half the embodied carbon of liftable stones and nearly six times less than stone slips with a secondary steel structure. Additionally, this methedology removes the need for lintels and porches so will further save on embodied carbon. Finally the small number of pieces per house means that construction time will be quick so labour cost can be saved.
102
Liftable stone
Large stone
Stone slips + steel structure
ROYAL COLLEGE OF ART ADS5
HOUSES
Figure 3.38 4 bedroom carbon copy
103
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3.0 CARBON COPY
STONE ROOF TILES
LIMESTONE OR SLATE? Taylor Wimpey use cement fibre tiles which only have a lifespan of 30 years. To make a cement fibre tile, stone must be quarried, crushed, fired, mixed and set. In contrast stone can be used for roofing which has a lifespan of 80100 years and the only processing required is quarrying and cutting to size. Immediately the environmental and carbon benefits of stone are clear.
HOUSES
Vernacular roofing in the Cotswolds typically uses ‘stone slates’, these are the local limestone handcut into tiles. They are naturally rough and thick therefore require a pitch of 50-55o to allow for adequate run-off. Welsh slate is another typical roofing material in the UK. Welsh slate is naturally very smooth and can be cut thinly so the pitch and overall material quantity can be much less than Cotswolds stone slates. We are proposing to use Welsh slate to minimise material, wasted loft space and maximise long lasting environmental benefits.
0.6 0
0.4
kgCO2e/m3
0.8
1
EMBODIED CARBON COMPARISON
104
Cement tiles
Stone slates
Welsh slate
ROYAL COLLEGE OF ART ADS5
COTSWOLDS STONE SLATES
Figure 3.39 Cotswold stone slate requires a roof pitch of 50o
HOUSES
WELSH SLATE
Figure 3.40 Welsh slate can use the same pitch as the existing condition
105
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3.0 CARBON COPY
TIMBER WINDOWS
VELFAC WINDOWS Plastic is one of the chief material issues plaguing our planet today. Windows can be made of recylced uPVC however, the process of dissasembling, melting and moulding them into new windows is extremely fuel intensive so far from ideal. Secondly, using plastic windows on houses designed to be environmentally friendly is antithetical to that ethos.
As a component, these windows are more expensive than the existing condition but they can be afforded through savings elsewhere. Velfac over uPVC windows also have a visual benefit that cannot be ignored.
COST COMPARISON
Cost per house/£
0
1 0
kgCO2e/kg
2
200
3
300
4
400
EMBODIED CARBON COMPARISON
100
HOUSES
Timber windows undergo far fewer processes in becoming a window but must be externally treated (with oil, wax, paint or similar) to prevent decay. Velfac windows are a composite of external aluminium and internal timber which means that they do not require much maintenance and still sequester carbon.
2
-200
1
-100
uPVC
106
uPVC
Velfac
Velfac
ROYAL COLLEGE OF ART ADS5
UPVC
Figure 3.41 uPVC windows
HOUSES
VELFAC
Figure 3.42 Timber velfac windows
107
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3.0 CARBON COPY
TIMBER INTERNAL PARTITIONS
GREENER, CHEAPER
20000
EMBODIED CARBON COMPARISON
10000 5000 -5000
0
kgCO2e/m3
15000
HOUSES
The existing methedology for internal partition walls is a metsec frame with plasterboard finished with either paint or wallpaper. Metsec frames are quick to construct because they come pre-cut and drilled however a simple stud wall of softwood timber is equally easy to build, greener and cheaper. 15mm pine veneered plywood lines the partitions instead of plasterboard and an ancillary finish; this is more expensive but offset by the cheaper studwork and lack of need for extra layers of finish which not only reduce material costs but labour costs as well.
108
Metsec
Softwood Timber
ROYAL COLLEGE OF ART ADS5
METSEC
HOUSES
Figure 3.43 Existing condition metsec partitions and internal fit out
SOFTWOOD TIMBER
Figure 3.44 Proposed softwood timber partitions and veneered ply lining
109
ROYAL COLLEGE OF ART ADS5
3.0 CARBON COPY
TIMBER AND STONE FLOOR FINISHES
CARBON SEQUESTERING FLOORS Currently Taylor Wimpey use carpet or porcelain tiles throughout their houses. Carpet cannot be easily recycled and is often the first thing new owners will look to change; it also requires underlay which is equally difficult to recycle fully. Porcelain tiles require quarrying clay, firing, glazing and firing again so while cheap are very carbon intensive to fabricate.
HOUSES
Hardwood timber floors are not often replaced by new owners so not only do they sequester carbon, they reduce material wastage over the lifespan of the building. Limestone simply requires quarrying and cutting before it can be laid. Limestone should be finished with a biodegradable wax layer to protect it from stains. We are proposing to use hardwood timber floors throughout with the exception of bathrooms where limestone will be laid.
1 2
1
0
kgCO2e/kg
2
3
4
EMBODIED CARBON COMPARISON
110
Carpet
Porcelain Tile
Hardwood Timber
Limestone
ROYAL COLLEGE OF ART ADS5
CARPET AND TILE
HOUSES
Figure 3.45 Existing condition is mostly carpet and large areas of tile
TIMBER AND STONE
Figure 3.46 Proposed timber floors thorugh except for bathrooms where limestone is used
111
ROYAL COLLEGE OF ART ADS5
3.0 CARBON COPY
PLAN
HOUSES
3 BED
00
01
4 BED
112
0m
1
2
00
01
ROYAL COLLEGE OF ART ADS5
HOUSES
02
113
ROYAL COLLEGE OF ART ADS5
3.0 CARBON COPY
SECTION/ELEVATION
HOUSES
3 BED
4 BED
114
0m
1
2
ROYAL COLLEGE OF ART ADS5
HOUSES
115
ROYAL COLLEGE OF ART ADS5
3.0 CARBON COPY
FOUNDATION DETAIL 3 BED AND 4 BED
1
HOUSES
2
VOID
116
1
ROYAL COLLEGE OF ART ADS5 HOUSES
1
Wall 300mm timber I-joist frame 300mm hemp batt insulation 12mm veneered plywood 12x100mm softwood skirting
2
Floor 12mm Hardwood timber floor 22mm plywood 50x25mm Softwood timber battens Acoustic insulation Timber I-Joist Hemp batt insulation DPM
3
Foundation 2x75mm limestone block 150mm EPS insulation Vented opening 400x400x600 limestone plinth 600x600x300 limestone footing Reinforced concrete
117
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3.0 CARBON COPY
EXTERNAL WALL DETAIL 3 BED AND 4 BED
3
HOUSES
1
2
118
1
118
Wall 75mm limestone 50mm air gap Waterproof membrane 300mm timber I-joist frame 300mm hemp batt insulation 12mm veneered plywood
12x100mm softwood skirting 2
Window Triple glazed velfac timber window Limestone sill Hardwood timber sill
3
Intermediate floor 12mm Hardwood timber floor 22mm plywood 50x25mm Softwood timber battens Acoustic insulation Timber I-Joist 12mm veneered plywood
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HOUSES
119
119
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3.0 CARBON COPY
EAVE DETAIL 3 BED 2
HOUSES
1
120
3
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4 BED
3
1
HOUSES
1
Wall 75mm limestone 50mm air gap Waterproof membrane 300mm timber I-joist frame 300mm hemp batt insulation 12mm veneered plywood
12x100mm softwood skirting
2
Flat roof Sedum planting 200mm soil 100mm drainage board DPM 300mm timber I-joist Hemp batt insulation 12mm veneered plywood
3
Pitched roof Welsh slate tiles Softwood timber battens DPM 300mm timber I-joist Hemp batt insulation 12mm standard ply
121
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3.0 CARBON COPY
INTERNAL STRUCTURAL WALL DETAIL 3 BED (PARTY WALL) AND 4 BED
1
122
HOUSES
2
VOID
VOID
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1
Wall 300mm timber I-joist frame 300mm hemp batt insulation 12mm veneered plywood 12x100mm softwood skirting
2
Floor 12mm Hardwood timber floor 22mm plywood 50x25mm Softwood timber battens Acoustic insulation Timber I-Joist Hemp batt insulation DPM
123
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3.0 CARBON COPY
INTERNAL PARTITION WALL DETAIL 3 BED AND 4 BED
1
HOUSES
2
VOID
124
1
Wall 90mm softwood timber frame 90mm hemp batt insulation 12mm veneered plywood 12x100mm softwood skirting
2
Floor 12mm Hardwood timber floor 22mm plywood 50x25mm Softwood timber battens Acoustic insulation Timber I-Joist Hemp batt insulation DPM
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HOUSES
125
126 HOUSES
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3.0 CARBON COPY
COMPARATIVE IMAGES
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HOUSES
127
128 HOUSES
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HOUSES
129
130 HOUSES
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HOUSES
131
HOUSES
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3.0 CARBON COPY
EMBODIED CARBON
MATERIAL
ELEMENT
VOLUME M3
EMBODIED CARBON KGCO2E
Limestone
Pad foundation
4
756
Limestone
Wall
16
2914
Softwood I-beam
Wall and floor
<1
-2030
Softwood
Wall and floor
6
-3888
Softwood
Stud partitions
2
-1139
Plywood
Linings/floors
16
-8079
Welsh slate
Roof tiles
2
408
Softwood
Roof trusses
n/a
-473
Hemp batt
Insulation
109
-2389
Glass
Windows
<1
380
Limestone
Sills and lintels
<1
49
132
TOTAL/HOUSE
-13489
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COST ANALYSIS
ELEMENT
QUANTITY M2
COST £
Limestone
Pad foundation
4m3
1200
Limestone
Wall
16m3
4626
Softwood I-beam
Wall and floor
<1
Unknown
Softwood
Wall and floor
507
5065
Softwood
Stud partitions
284
2840
Plywood
Linings/floors
1322
19,830
Welsh slate
Roof tiles
2m3
648
Softwood
Roof trusses
103
1028
Hemp batt
Insulation
109m3
15,025
Glass
Windows
14
6750
Limestone
Sills and lintels
<1m3
78
TOTAL/HOUSE
HOUSES
MATERIAL
57,270
133
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3.0 CARBON COPY
FINDINGS
GREENER, CHEAPER, FASTER Our analysis has proved that it is possible to build a carbon copy scheme of that built by Taylor Wimpey that is carbon negative. Not only this, our scheme is comparatively cheaper to build per house due to the change and reduction of materials, desiging out supplementary finishes and faster construction techniques.
HOUSES
Our carbon copy scheme is more at home in the Cotswolds than that proposed by Taylor Wimpey and will be more comfortable for residents to live in. This analysis has been concluded in a vaccum however, and it would therefore be interesting to see how our design could be rolled out to other Taylor Wimpey sites and investigate how this may have positive effects. A second additional study that would be good to do is looking into how these homes are serviced - could a district ground source heat pump be viable for the whole development to share? Will this cheapen users’ bills and increase their fuel security?
COST COMPARISON
150000 -50000
Existing Condition
Stone + CLT
Stone + Timber Frame
-100000
-40000
134
100000 50000 0
0
Existing Condition
Large stone
-20000
kgCO2e/m3
20000
40000
Cost per house/£
200000
EMBODIED CARBON COMPARISON
Stone + CLT
Stone + Timber Frame
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Figure 3.48 3 bedroom carbon copy
168%
24%
EMBODIED CARBON
PROJECT COST
135
136 HOUSES
4.0 WHAT IF?
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4.0 WHAT IF?
SUMMARY
LOADBEARING STONE Traditionally the stone of vernacular houses in the Cotswolds is not just a rainscreen but also structure. If we were to go beyond the carbon copy and design further, this would be our principle approach. The following two options briefly explore how it can be articulated either as external stone or as internal stone.
138
HOUSES
Additionally we have explored the use of timber piles in lieu of limestone for foundations. This would mean that our foundations, which have one of the highest individual component embodided carbon figures, will be carbon negative for each house. The following have all been designed as ideas, ‘what if?’ scenarios and therefore require further investigation, especially into accurate cost and carbon calculations
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Figure 4.1 Typical Cotswolds cottage
139
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4.0 WHAT IF?
INTERNAL STONE
INSULATED RENDER HIDING COSY VERNACULAR STONE INTERIOR Internal structural stone offers fantastic environmental and visual possibilities. Firstly, by making the stone loadbearing, we will eliminate the need for a timber frame and reduce wall build-up so reduce material quantites and cost. Secondly it frees the external elevations to, in essence, become anything it wants. One route we have explored is to use insulated render so each house becomes a black (or coloured) box where no lintels or roof tiles are required as it is all wrapped in a homogenous envelope.
HOUSES
Reducing the wall build-up, material quantites and improving the u-value can only be a good thing. These houses will externally appear out of place but in actual fact can be argued to be more ‘vernacular’ than our proposed carbon copy because their stone is loadbearing. The internal palette of exposed stone and timber panelled partitions will create a cosy, cottage atmosphere. The simple and cheap facade can mean more money is put into planting, which will create a richer environment for people to enjoy and biodiversity to thrive.
Figure 4.2 Ada Street, Groupwork
140
Figure 4.3 Didden Village, MVRDV
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1
Figure 4.4 Internal stone walls
1
Limestone wall Dryvit insulated render system 300mm rigid wood fibre insulation Waterproof membrane 125mm limestone
141
142 HOUSES
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Figure 4.5 Prospect Cottage, Derek Jarmin
Figure 4.6 Serpentine Pavillion, Peter Zumthor
143
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4.0 WHAT IF?
EXTERNAL STONE
CUTE DORMERS External stone means the houses will contextually appear at home which is of course something to be prized - the typical Cotswold cottage is cute and sought after for a reason. Wall build-up and material quantities will again be reduced by making the stone loadbearing. However to avoid thermal bridges and areas for condensation to creep into the building, a complex insulated hanging detail is required for the floor joists which could increase costs.
HOUSES
To mitigate any potential cost increases, we have explored dropping the ceiling on the 4 bedroom house and added cute little dormers typical of the area. This, coupled with the elimination of a timber frame, will reduce material quanitities and indeed cost.
144
Figure 4.8 Cute little dormers set into a Cotswolds cottage
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Figure 4.9 4 bedroom with low roof and dormers
145
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NO NIA LOSS
1200
HOUSES
The roof pitch starts 1200mm above FFL and therefore there is no loss of NIA/net sellable area.
146
0m
1
2
Floor joists can hang directly off the external loadbearing stone work with a nylon insulation strip to avoid cold bridges. As the wall panels only need to hold themselves up now, the timber frame can be removed so much less material is used and less work required per house. The stone must increase to a thickness of 125mm but there is no impct on overall build-up.
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INSULATED FLOOR JOIST HANGER
1
HOUSES
2
1
Limestone wall 125mm limestone 50 air gap Waterproof membrane Cavity ties 15mm plywood 300mm insulation 12mm veneered plywood 12mm timber skirting
2
Intermediate floor Nylon insulation strip Steel hanger 300mm timber I-joist Acoustic insulation Softood timber battens 22mm plywood 12mm hardwood floor
147
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4.0 WHAT IF?
TIMBER PILE FOUNDATIONS
CARBON NEGATIVE FOUNDATIONS The foundations in our carbon copy are still very carbon intensive at +756kgCO2e/m3 and dramatically more expensive than the existing methedology of concrete block. We have therefore looked to use timber piles made of oak or coppice chestnut which would make our foundations carbon negative and increase the construction speed. Timber pile foundations will most likely be greener, cheaper and faster. Timber piles are used reguarly for fencing that lasts 60+ years in the post and rail fencing of southern England. Setting the pile 3m deep will mean they can withstand any heaving or settling forces. A galvanised steel flange must be inserted into the top of each pile to retain the strength in case the timber starts to rot at the top of ground level. HOUSES
The main design feature that this method would bring about is the need to leave 300mm of the timber above ground level to ensure the underside of the house can be adequately ventilated to avoid rot. We can take advantage of this however and introduce a ramp over linked swales on the front and back of each house. This will ensure equal access, increase biodiversity, help reduce flood risk and increase the beauty of the masterplan.
148
Figure 4.10 Chestnut post and rail fencing can last outdoors for 60 years
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PROPOSED STONE PADS
2000
300
600x600x300mm limestone
2700
HOUSES
2700
2700
300
PROPOSED TIMBER PILES
2700
2700 3000
2700
300x3000mm timber 600x220x10mm steel flange
149
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VOID
HOUSES
2
150
1
1
Foundation 3000x300mmdia. chestnut or oak pile 800x220x10mm galvanised steel flange
2
Swale Water loving planting
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Figure 4.11 Ramp over swale entrance
Figure 4.12 Tasinge Plads, Copenhagen Planted swales with walkways over the top
151
152 HOUSES
5.0 FINDINGS
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HOUSES
153
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5.0 FINDINGS
FINAL COMPARITIVE FINDINGS
GREENER, CHEAPER, FASTER This analysis has explored if it is possible to recreate a Taylor Wimpey housing development that is greener, cheaper and faster than the existing condition. Through our research we have concluded that it is indeed possible. Thoughtful questioning of, and, understanding material along with construction methods means that these houses can be built using a timber frame and large self supporting Cotswolds limestone facade.
154
HOUSES
This research is in essence only a beginning, it is a provocation of what is possible when we think and deeply analyse design decisions. Changing a material based on cost or colour alone does not look at the whole picture and doing so does an injustice to the future residents of these homes and our shared planet. This analysis has been done in the isolation of two typologies on a single site. The next steps to develop this research further would be to present it to Taylor Wimpey and work together to understand how this could work at an economy of scale. Secondly, this research has been more site specific than a Taylor Wimpey development in which the same house can be built in Southampton or Sunderland so developing a map of Britain and housing typologies accordingly that are all greener, cheaper and faster would be an incredibly interesting and pertinent exercise.
168%
24%
EMBODIED CARBON
PROJECT COST
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COST COMPARISON
100000 0
50000
40000 20000 0
Existing Condition
Stone + CLT
Stone + Timber Frame
Existing Condition
Stone + CLT
Stone + Timber Frame
-100000
-50000
-20000
Large stone
-40000
kgCO2e/m3
HOUSES
Cost per house/£
150000
200000
EMBODIED CARBON COMPARISON
155
156 HOUSES
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HOUSES
157
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6.0
CATALOGUE OF MATERIAL COMPONENTS
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HOUSES
159
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6.0 CATALOGUE OF MATERIAL COMPONENTS
FOUNDATION DETAIL 3 BED AND 4 BED
1
HOUSES
2
VOID
160
1
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1
Wall 300mm timber I-joist frame 300mm hemp batt insulation 12mm veneered plywood 12x100mm softwood skirting
2
Floor 12mm Hardwood timber floor 22mm plywood 50x25mm Softwood timber battens Acoustic insulation Timber I-Joist Hemp batt insulation DPM
3
Foundation 2x75mm limestone block 150mm EPS insulation Vented opening 400x400x600 limestone plinth 600x600x300 limestone footing Reinforced concrete
161
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6.0 CATALOGUE OF MATERIAL COMPONENTS
EXTERNAL WALL DETAIL 3 BED AND 4 BED
3
HOUSES
1
2
162
1
Wall 75mm limestone 50mm air gap Waterproof membrane 300mm timber I-joist frame 300mm hemp batt insulation 12mm veneered plywood
12x100mm softwood skirting 2
Window Triple glazed velfac timber window Limestone sill Hardwood timber sill
3
Intermediate floor 12mm Hardwood timber floor 22mm plywood 50x25mm Softwood timber battens Acoustic insulation Timber I-Joist 12mm veneered plywood
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HOUSES
163
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6.0 CATALOGUE OF MATERIAL COMPONENTS
EAVE DETAIL 3 BED 2
HOUSES
1
164
3
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4 BED
3
1
HOUSES
1
Wall 75mm limestone 50mm air gap Waterproof membrane 300mm timber I-joist frame 300mm hemp batt insulation 12mm veneered plywood
12x100mm softwood skirting
2
Flat roof Sedum planting 200mm soil 100mm drainage board DPM 300mm timber I-joist Hemp batt insulation 12mm veneered plywood
3
Pitched roof Welsh slate tiles Softwood timber battens DPM 300mm timber I-joist Hemp batt insulation 12mm standard ply
165
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6.0 CATALOGUE OF MATERIAL COMPONENTS
INTERNAL STRUCTURAL WALL DETAIL 3 BED (PARTY WALL) AND 4 BED
1
166
HOUSES
2
VOID
VOID
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1
Wall 300mm timber I-joist frame 300mm hemp batt insulation 12mm veneered plywood 12x100mm softwood skirting
2
Floor 12mm Hardwood timber floor 22mm plywood 50x25mm Softwood timber battens Acoustic insulation Timber I-Joist Hemp batt insulation DPM
167
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6.0 CATALOGUE OF MATERIAL COMPONENTS
INTERNAL PARTITION WALL DETAIL 3 BED AND 4 BED
1
HOUSES
2
VOID
168
1
Wall 90mm softwood timber frame 90mm hemp batt insulation 12mm veneered plywood 12x100mm softwood skirting
2
Floor 12mm Hardwood timber floor 22mm plywood 50x25mm Softwood timber battens Acoustic insulation Timber I-Joist Hemp batt insulation DPM
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HOUSES
169
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EXTERNAL CONTRIBUTORS
WEBB YATES ENGINEERS 48-50 Scrutton Street London EC2A 4HH london@webbyates.com
EIGHT ASSSOCIATES
HOUSES
46 Loman Street London SE1 0EH info@eightassociates.co.uk
OLP COST CONSULTANTS Office 7 35-37 Ludgate Hill London EC4M 7JN info@olpcostconsultants.co.uk
IVO DESIGN +44 (0) 7954 09 81 31 +34 623 104 054 ivo@ivodisseny.com
NORTON ROSE FULBRIGHT 3 More London Riverside London SE1 2AQ
170
+44 20 7283 6000
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171