Building with Earth by Birkhäuser

This manual, now in its fourth and revised edition, describes the building technology of rammed earth. The physical properties and characteristic values are explained in a hands-on manner: With proper moisture protection, earth buildings are very durable, and in particular the combination with wood or straw allows a wide spectrum of design options. Twenty-six international built examples demonstrate the range of applications for this fully recyclable material.

Gernot Minke Minke BUILDING WITH EARTH

Earth, in common use for architectural construction for thousands of years, has in recent years attracted new attention as a healthy, environment-friendly and economical building material. An impressive number of buildings has been realized not just in hot and dry regions but also in the colder climates of Europe and North America. Technical innovations such as prefabricated rammed earth components and clay panels facilitate the use of this sustainable material.

BUILDING WITH EARTH Design and Technology of a Sustainable Architecture

ISBN 978-3-0356-2253-9

www.birkhauser.com

Fourth and revised edition

Table of contents Preface 7 1

Introduction 9 History 9 Earth as a building material: the essentials 11 Improving indoor climate 13 Prejudices against earth as a building material 16

2 The properties of earth as a building material 17 Composition 17 Tests used to analyse the composition of loam 19 Effects of water 22 Effects of vapour 26 Influence of heat 29 Strength 30 pH-value 32 Radioactivity 33 Shelter against high-frequency electromagnetic

Working with earth blocks 60 History 60 Production of earth blocks 61 Material composition 64 Laying earth blocks 64 Surface treatment 65 Fixing fasteners to walls 65 Lightweight earth blocks 65 Special acoustic green bricks and adobes 66

7 Large blocks and panels 67 Large blocks 67 Earth-filled wall panels 67 Clay panels 69 Heating panels 71 Floor slabs 71 Floor tiles 72 Extruded loam slabs 72

radiation 33 3 Preparing of loam 34 Soaking, crushing and mixing 34 Sieving 36 Mechanical slurrying 36 Water curing 36 Thinning 36 4 Improving the characteristics of loam by special treatment or additives 37 Reduction of shrinkage cracks 37 Stabilisation against water erosion 38 Enhancement of binding force 40 Increasing compressive strength 40 Strength against abrasion 45

Increasing thermal insulation 45 Lightweight loams 46

Rammed earthworks 50 Formwork 51 Tools 52 Method of construction 53 Shaping of openings 54 Wall construction techniques 54 Rammed earth domes 59 Drying 59 Labour input 59 Thermal insulation 59 Surface treatment 59

8 Direct forming with wet loam 73 Traditional wet loam techniques 73 The “Dünne loam loaf” technique 75 The stranglehm technique 75 9

Wet loam infill in skeleton structures 80 Thrown loam 80 Sprayed loam 80 Rolls and bottles of straw loam 81 Lightweight loam infill 81 Infill with stranglehm and earth-filled hoses 82 Sprayed loam in steel-reinforced walls and ceilings 82

10 Tamped, poured or pumped lightweight loam 85 Formwork 85 Tamped lightweight straw loam walls 85 Tamped lightweight wood loam walls 87 Tamped, poured or pumped lightweight mineral loam walls 87 Pumped lightweight mineral loam floors 88 Loam-filled hollow blocks 88 Loam-filled hoses 90 11

Loam plasters 92 Preparation of substrate 92 Composition of loam plaster 92 Guidelines for plastering earth walls 94 Sprayed lightweight plaster 94 Lightweight mineral loam plaster 95

Thrown plaster 95 Plastered straw bale houses 95 Wet formed plaster 97 Protection of corners 97 Stabilised loam plasters 97 Characteristics of different loam plasters 97

Weather resistance, coatings and coverings 100 Consolidating the surface 100 Paints 100 Making surfaces water-repellent 101 Lime plasters 104 Shingles, planks and other covers 105 Structural methods 105

13 Repair of loam structures 106 Occurrence of damage 106 Repair of cracks and joints with loam fillers 106 Repair of cracks and joints with other fillers 107 Repairing larger damaged areas 107 Retrofitting thermal insulation with lightweight loam 107 14

Customised design solutions 109 Joints 109 Special wall constructions 111 Intermediate floors 113 Rammed earth floorings 113 Inclined roofs filled with lightweight loam 115 Earth-covered roofs 115 Earth block vaults and domes 117 Earthen storage wall in winter gardens 129 Loam in bathrooms 129 Built-in furniture and sanitary objects from loam 131 Passive solar wall heating system 132

15 Earthquake-resistant building

133 Structural measures 134 Openings for doors and windows 136 Bamboo-reinforced rammed earth walls 139 Steel-reinforced sprayed loam walls 139 Steel-reinforced adobe wall system 141 Domes 141 Vaults 141 Textile walls with loam infill 144 Steel-reinforced earth walls 146

Built examples Residences Low compound, Scottsdale, Arizona, USA 148 Residence cum office, Kassel, Germany 150 Vineyard residence, Mornington Peninsula, Victoria, Australia 152 Residence, Merrijig, Victoria, Australia 154 Residence, Helensville, New Zealand 156 Residence, Palo Alto, California, USA 158 Weekend house, Ajijic, Mexico 160 Artist’s residence, Boulder, Colorado, USA 162 Residence, Emboscada, Paraguay 164 Cultural, educational and sacred buildings National Environment Centre at Thurgoona Campus, Albury, New South Wales, Australia 166 School, Rudrapur, Bangladesh 168 Chapel of Reconciliation, Berlin, Germany 170 WISE Centre for Alternative Technology, Machynleth, Wales, UK 172 Primary school, Tanouan Ibi, Mali 174 Cemetery, Bushey, Hertefordshire, UK 178 The Village Nursery, Bellingdon, Buckinghamshire, UK 182 Centre for People with Disabilities and Dipdii Textiles Studio, Rudrapur, Bangladesh 186 Adobe Dome Music Space, Aiguá, Uruguay 190 Burkina Institute of Technology, Koudougou, Burkina Faso 194 Maison pour tous, Four, Isère, France 198 Commercial, hospitality and health buildings Rivergreen Centre, Aykley Heads, Durham, UK 202 High Country Visitor Information Centre, Mansfield, Victoria, Australia 204 Twelve Apostles Visitor Amenity Building, Port Campbell, Victoria, Australia 206 Mii Amo Spa, Sedona, Arizona, USA 208 Bayalpata Hospital, Acham, Nepal 210 Alnatura Office Building, Darmstadt, Germany 214

Bibliography 218 About the author 221 Illustration credits 221 Subject index 222

1.1

1.2

Introduction

1 Introduction

is the most important natural building material, and it is available in most regions of the world. It is frequently obtained directly

1.3

1.1 Citadel of Bam, Iran, before earthquake of December 2003 1.2 Tulou of the Hakka in Fujian, Nanjing, China: A timber roof construction with a courtyard and rammed earth walls. 1.3 Fortified City, Draa valley, Morocco, 15th century

In nearly all hot-arid and temperate climates, earth has always been the most prevalent building material. Even today, one third of the human population resides in earthen houses; in developing countries this figure is more than one half. It has proven impossible to fulfil the immense requirements for shelter in the developing countries with industrial building materials, i.e. brick, concrete and steel, nor with industrialised construction techniques. Worldwide, no region is endowed with the productive capacity or financial resources needed to satisfy this demand. In the developing countries, requirements for shelter can be met only by using local building materials and relying on do-it-yourself construction techniques. Earth Introduction

from the building site when excavating foundations or basements. In the industrialised countries, careless exploitation of resources and centralised capital combined with energy-intensive production is not only wasteful; it also pollutes the environment and increases unemployment. In these countries, earth is being revived as a building material. Increasingly, people when building homes demand energy- and cost-effective buildings that emphasise a healthy, balanced indoor climate. They are coming to realise that mud, as a natural building material, is superior to industrial building materials such as concrete, brick and lime-sandstone. Newly developed, advanced earth building techniques demonstrate the value of earth not only in do-it-yourself construction, but also for industrialised construction involving contractors. This handbook presents the basic theoretical data concerning this material, and it provides the necessary guidelines, based on scientific research and practical experience, for applying it in a variety of contexts.

History Earth construction techniques have been known for over 9000 years. Mud brick (adobe) houses dating from 8000 to 6000 BC have been discovered in Russian Turkestan (Pumpelly, 1908). Rammed earth foundations dating from ca. 5000 BC have been

Plaster

Leightweight loam

Soil blocks

Rammed earth Plaster

5.28

Plaster Soil blocks Thermal insulation Lightweight loam

Bricks Lightweight loam Thermal insulation Mud plaster

Soil blocks

Plaster Thermal insulation Lightweight loam Lightweight loam board Mud plaster

Timber panels Protection layer Thermal insulation Lightweight loam Gypsum board

5.29

footprint is too small to accommodate an onsite rammed earth wall with a depth of 46 to 60 cm. Wall construction with lost formwork As with rammed earth techniques, the cost of the formwork is quite high. In some cases, it is preferable to use a thin masonry wall or stiff thermal insulation elements made of wooden materials as lost formwork, so that either no formwork or only one-sided formwork is required. It is also advantageous if this formwork can contribute to a substantial increase in thermal insulation. The stiffness of this lost formwork has to be sufficient to take care of the lateral impacts created by ramming. Illustration 5.28 shows horizontal sections through an external wall. The first two cases show an inner leaf built of adobes or soil blocks and an outer rammed earth layer made with lightweight mineral loam which 57

is directly plastered. In this case the formwork is only required for the outer face. In the second case, a somewhat better stiffness of the inner adobe or soil block leaf is attained due to the bonding pattern in the components. In the section shown on the right, the lost formwork is on the outside and is made from stabilised lightweight soil blocks. Illustration 5.29 shows vertical sections of external walls that have lost formwork on both sides. The inner leaf can be made from adobes or soil blocks, larger prefabricated loam elements, or stiff plywood boards, fibre-reinforced gypsum boards, or Magnesite or cement-bonded wood particleboard. Protection of the wall surface against the elements can be achieved by plaster, masonry or timber panelling with air cavity. Prefabricated rammed earth elements In recent years, companies in France, AusWall construction techniques

tria, the USA and Germany, for instance, built walls with prefabricated elements. They were produced in a factory or in a locally built-up sheltered production line. The advantages of this technique is a reduced erection time, so that normally no special weather shelter is needed. The disadvantage are the higher costs. A recent example built in Germany by the Austria-based company Lehm Ton Erde Baukunst was the Alnatura office building in Darmstadt (pp. 214–217) where a temporary field factory was established (5.30). The company started to experiment with prefabricated parts in 1997 and by 2015 already one third of its work relied on prefabrication. Instead of gradually ramming the material into the formwork at the building site, wall segments are prefabricated and then assembled on site (Rauch, 2020). To reduce the amount of formwork required, a so-called endless wall (5.31 and 5.32) is produced in

5.30

5.31

5.32

5.34

5.33

Rammed earthworks

7.9

7.10

7.11

7.12

7.13

Clay panels

isting wall with clay mortar or screwed onto a framework. The panels boost the thermal insulation effect of the wall. They may contain reed, hemp shives, straw chippings, wood chips, perlite or expanded glass and their raw densities range from 500 to 800 kg/m³. Pure loam panels with a raw density of approximately 1500 kg/m³ exist as well; they increase the heat storage effect and improve the air humidity balance.

7.3 Making lightweight mineral loam blocks, Tata, Hungary 7.4 Using lightweight mineral loam blocks as external additional thermal insulation for a rammed earth wall, Tata, Hungary 7.5 Lightweight loam blocks for wall construction 7.6 Lightweight loam blocks for vaults 7.7 Interior wall from lightweight loam panels 7.8 Structural elements filled with lightweight loam 7.9 Lightweight earth boards for thermal insulation (by Lehmwerk Kleinfahner) 7.10 Lightweight earth blocks for thermal insulation (by Lehmwerk Kleinfahner) 7.11 Heavy clay panel with loam, clay, wood fibres, starch, jute fabric (by Claytec) 7.12 and 7.13 Lightweight clay panel with reed for interior use (by Claytec)

In recent years, several companies in Europe have introduced clay panels into the market, sometimes also called loam boards, earth building boards or loam panels. In the meantime a standard, DIN 18948, for these panels has been established. These products are thin boards, mostly 16 to 25 mm thick, 62.5 cm wide and up to 150 cm long. They are used in interior construction to clad walls without introducing much moisture as would be the case with the usual plastering of walls. Only the joints have to be plastered over. Depending on the type of surface structure, they can be covered directly with paint, wallpaper or with a 1- to 2-mm-thick clay plaster. The panels are either fixed to an exClay panels

In Germany, the company Claytec produces 62.5 × 125 cm boards that are 16 or 22 mm thick and have a gross density of 1450 kg/m³ (7.11), as well as a 20- and 25-mm-thick lightweight board that measures 62.5 × 150 cm and has a gross density of 700 kg/m³ (7.12 and 7.13).

7.14

7.15

7.16

7.17

7.18

7.19

Large blocks and panels

Vineyard residence Mornington Peninsula, Victoria, Australia

Architect: John Wardle Architects, Melbourne, Australia Completion: 2002 Wall system: Rammed earth Floor area: 400 m² The predominant elements of this residence, which is situated in a large vineyard, are the rammed earth walls. The living area extends out to the north veranda, the kitchen to an informal terrace area. The study opens up to the garden. The principal bedroom, with its walls angling outward, evokes the impression of continuing into the landscape. The entry screen reduces western sun into the living area. Cross ventilation is achieved throughout all areas.

152

Built examples

153

Residences

Artist's residence Boulder, Colorado, USA

Architects: Tres Birds (Michael M. Moore, Shawn Mather, John Bezouska) Structural engineer: Gebau Engineering Floor area: 650 m² Wall system: Rammed earth in layers of different colours Completion: 2013 The 650 m² private residence for Boulder artist Rebecca DiDomenico, marks North Boulder with a new iconic landmark. The structure was built using 180 tonnes of regional soil, compressed into 76-cm-thick walls. This adds significant thermal mass to the building’s whole, optimal for temperature regulation. By mixing different mineral colours into the soil and creating different layers of varying heigths during the ramming process, an artistic design was created. Some parts of the surface were even carved. The outer wall was covered with a transparent paint as a barrier against rain erosion. Floors were ground to the point of reaching their natural polish and stacked black river rocks make up the bathroom walls. Spanish Cedar as well as reclaimed railroad boxcar flooring blend the building’s earth tones with the stark white walls. The project is energised using 100% renewable resources, demonstrating fossil-free potential of the built environment. Four vertical geothermal wells were installed to transfer the earth’s energy to the building’s heating and cooling system. A photovoltaic roof on the carport generates energy for interior LED lighting and electricity. To test the energy efficiency of the structure, a Home Energy Rating System (HERS) was performed, ranking it in the 74th percentile and exceeding code requirements by three times.

2 6 3 4

7 2

8 9 10 11

12 13 14 15 RE: CIVIL

12" CLOSED CELL FOAM R-44 AT ROOF LVL FRAMING SPACING RE: STRUCT STRUCTURAL STEEL ARCH RE: STRUCT

WINDOW ASSEMBLY DOUBLE PANED R-5 TYPICAL

RAMMED EARTH WALL ASSEMBLY

1 Framed walls 2 Concrete floor 3 Steel joists 4 Steel stringer 5 Arched steel support 6 Concrete wall 7 Sliding door system 8 Floor joists

PORTHOLE DORMER BEYOND

9 Beam 10 Foundation wall 11 Foundation insulation 12 Concrete slab 13 Foundation footing 14 Perimeter drain 15 Underslab drainage 16 Column 12" CLOSED CELL FOAM/BATT R-44 AT ROOF

STRUCTURAL STEEL ARCH RE: STRUCT

WALL BEYOND

GLASS PANELS ALONG FRONT OF ROOMS

EXHAUST FAN

CONCRETE SLAB HALF WALL CONCRETE SLAB FLOOR

RAMMED EARTH WALL ASSEMBLY 12" RAMMED EARTH 6" INSULATION 12" RAMMED EARTH

CONCRETE SLAB HALF WALL CONCRETE SLAB FLOOR W/1" INSULATED FOAM

FLOOR JOISTS RE: STRUCT. FOUNDATION WALL RE: STRUCT FOUNDATION INSULATION CONCRETE SLAB, RE: STRUCT FOUNDATION FOOTING RE: STRUCT

PERIMETER DRAIN RE: CIVIL UNDERSLAB DRAINAGE RE: CIVIL

162

Built examples

FLOOR JOISTS RE: STRUCT. FOUNDATION WALL RE: STRUCT UNCONDITIONED CONCRETE SLAB, RE: STRUCT FOUNDATION FOOTING RE: STRUCT

PERIMETER DRAIN RE: SOILS ENGINEER UNDERSLAB DRAINAGE RE: SOILS ENGINEER

163

Residences

Adobe Dome Music Space Aiguá, Uruguay

Design and supervision dome: Gernot Minke, Kassel, Germany Organisation and supervision: Macarena Albarracin, Santiago Escarrá, Salta, Argentina Completion: 2020 Vault system: Adobe masonry without formwork Floor area: 38.5 m² At a farm on the outskirts of the small town of Aiguá, a dome was built from adobe, designed for relaxation, meditation and music-making for up to 50 people. Due to its special acoustics, the building also serves as a recording studio for experimental music. The inner diameter of the dome is 7 m, the clear height in the middle is 5.40 m. The foundation and plinth as well as the circular entrance are made of locally available natural stones. The entrance has a diameter of 1.60 m, so the room has to be entered in a stooped position and its height is only experienced once inside. The floor slopes 20 cm towards the centre, so that no horizontal level is perceptible. This creates a special spatial impression, resulting in a sense of security and well-being. The top has an opening which is covered by an octagonal, pyramidical skylight, exuding a sense of being in touch with the cosmos. The dome was built during a two-week workshop directed by the author with the assis-

190

tance of Macarena Albarracin and Santiago Escarrá. It was built up utilising the “acoustic adobes” developed by the author. These have rounded edges to diffuse the sound reflection and are walled up at an angle of approximately 20° to the outside to reflect part of the sound upwards, thus reducing the focusing of the reflected sound towards the centre of the room. In addition, the joints have been recessed to improve sound absorption. In order to achieve the statically optimal cross-section of the dome, the rotational guide developed by the “Research Laboratory for Experimental Building” at the University of Kassel was used, which defines the correct position for each adobe. On the

Built examples

outside, the dome was first covered with a two-layer earth plaster and then sealed with a fleece-reinforced acrylic paint to make it weatherproof. The last layer of the transparent paint was mixed with sand and clay powder to achieve a clay-like appearance and to provide additional protection against ultraviolet radiation. The floor is made of rammed earth, its surface is divided into eight fields and a central octagon by wooden strips. The top layer of the floor consists of an approximately 2-cmthick earth render, which has been stabilised with some lime and cement.

191

Cultural, educational and sacred buildings

Burkina Institute of Technology Koudougou, Burkina Faso

Architect: Kéré Architecture, Jaime Herraiz Completion: 2020 Wall system: Cement-stabilised rammed earth Floor area: 1000 m² The Burkina Institute of Technology is based on a system of repeated modules, housing classrooms and auxiliary functions, arranged orthogonally to define a rectangular courtyard. The orthogonal layout of modules allows the campus to be expanded incrementally according to its needs. The modules are staggered, allowing air to flow through the central void, creating a cool space where students can relax and interact. The walls are made of cement-stabilised local lateritic clayey soil poured into the onestorey-high formwork and then rammed by a special vibrator. Due to the special mixture, which contains a high content of large particles, it was sufficient to use for stabilisation only 4.5% of cement by mass, which corre-

7 9

sponds by volume to 100 kg per m³. The basic mixture contains per volume 57% of soil, 29% of crushed granite 05/15 and 14% of coarse sand. The formwork was removed after 4 weeks. The roof profiles, repeated regularly, create a dynamic rhythm and form a chimney at the back of each module where warm air can be released. Suspended ceilings, made of local eucalyptus wood, brighten the interior spaces.

During the rainy season, water is channeled into a large underground tank and stored there. It is later used to irrigate the extensive mango plantations on the campus.

194

6 8

0 1 0 1 2 2

1 Auditorium 200 seats 2 Auditorium 100 seats 3 Computers 4 Classroom 5 Exterior lessons

Built examples

5 5

6 Teachers' room 7 Students' room 8 Teachers' bathroom 9 Students' bathroom

1010m

0 1 2

195

Cultural, educational and sacred buildings

196

Built examples

197

Cultural, educational and sacred buildings

Maison pour tous Four, Isère, France

Architect: designbuildLAB/ENSAG with onSITE architecture Completion: 2019 Wall system: Rammed earth Floor area: 151 m² The community centre “Maison pour tous” for the village of Four in the Auvergne-RhôneAlpes region of France was designed and built by the masters studio “designbuildLAB” of the “Ecole Nationale Superieure d’Architecture de Grenoble”, under the supervision of Professors Marie and Keith Zawistowski. It comprises a multi-purpose hall as well as technical space and storage. Towards the north, a plaza was added that accommodates outdoor events. On the other side of the building, earth excavated for the foundations was mounded to generate terraced seating. The open-plan centre is characterised by large roof overhangs that passively warm or shade the hall. Punched openings with glazed, larch frame accordion doors link its space to the surrounding landscape. The project draws on the vernacular architectural tradition in south-eastern France that once was dominated by unstabilised rammed earth buildings (Zawistowski, Zawistowski and Joffroy, 2020).

S AL L E DE R E UN A S S O C I A T I

5 RUE DE LA LUMINIERE - 380

MAI T R I S E D' OUV C OMMUNE

A. T. M.

AS S I S T ANCE A MAI T R I S E D' OUV

COMMUNAUTE D'AGGLOM P OR TE DE L'I

x x

A. T. M.

x x x x

MAI TR I S E D'OEU

x x

A R C H I T E C

ON S I T E AR C HI T E C

A. T. M.

x x

BET S TR UCTUR E &

A. T. M.

x x

B E T P AY S AGE &

AT E L I E R T AK T P AY

x x

A. T. M.

B E T

F L U I D

TECHNIQUES ENERGE D U B A T I M A. T. M.

B UR E AU DE CONT ALPES

C ONTR

A. T. M.

C OO R D I N A T E U R ALPES

C ONTR

A. T. M.

DATE EMETTEUR CODE PROJET PHASE INDICE TYPE ECHELLE

19/0

DBL

PLAN GENE N

0 0

198

Built examples in detail

2 2

4 4

10 10

20 m 20

600 mm rammed earth, finished on the exterior, corner chamfered Sealing membrane 20 mm chamfer between rammed earth wall and foundation In-situ concrete foundation, 600 × 400 mm

0 0

199

Cultural, educational and sacred buildings

0.50 0.5

1 1

2.50 2.5

55 mm

200

Built examples

201

Cultural, educational and sacred buildings

Bayalpata Hospital Acham, Nepal

Architects: Sharon Davis Design, New York; Ethicons-EWES J/V, Nepal Builder of earth walls: Subedi-Associate J/V Completion: 2019 Wall system: Reinforced rammed earth Floor area: 4227 m² The new Bayalpata Hospital, made possible through a collaboration between the government of Nepal and the NGO Possible Health, transformed an aged and overrun clinic into a model of sustainable rural health care facility. The 3-hectare campus with a built area of 4227 m² is set on a hilltop and surrounded by the terraced slopes of the Seti River valley. It includes five medical buildings that house outpatient, inpatient, surgery, antenatal and emergency facilities for 70 beds, plus clinical functions, such as pharmacy, radiology and laboratory spaces. An administration block with offices and a 60-seat canteen, plus ten single-family houses and an eight-bedroom dormitory, serve the hospital’s staff and their families. Bayalpata delivers low-cost, high-quality care to more than 100,000 patients a year from Achham and its six surrounding districts, more than eight times of the hospital’s original capacity. The facility now serves a population of 1 million. The architects used the locally available clayey soil stabilised with 6% of cement and vertical steel rebars for the rammed earth walls and the local stone for foundations and retaining walls. Photovoltaic cells on all south-facing roofs generate more energy on site than the campus requires. Passive heating and cooling are essential to the design, only the operating theatre within the surgery building is mechanically conditioned.

210

Built examples

211

Commercial, hospitality and health buildings

Gernot Minke Minke BUILDING WITH EARTH

BUILDING WITH EARTH Design and Technology of a Sustainable Architecture

ISBN 978-3-0356-2253-9

www.birkhauser.com

Fourth and revised edition