About Us
Earth Homes build homes made of earth (mud bricks), timber, straw, bamboo and earth friendly materials. To make mud bricks, the earth is mixed with water and reinforcing materials such as straw, and then pressed into wooden forms and allowed to set. The forms are removed and the bricks set aside to dry for up to several weeks. As they are made from natural materials they are a sustainable, recyclable, non-toxic and healthy form of building construction.
Building with heavy materials such as mud bricks, requires suitable footings such as a course of regular kiln fired bricks or concrete footings. They are held together with a mud mortar mixture which is similar in composition to the mud brick mixture itself. Mud bricks, being soft and un-fired, are easy to cut with hand tools, and can be formed into interesting shapes.
Once laying of the bricks is finished and the mortar is dry, the brick walls are often rendered with mud-based renders, although many mud brick walls are left natural, or are sealed with a transparent water-based sealant to improve weather resistance.
Mudbricks have many advantages, including low cost and low embodied energy (especially if they are made on site and not transported long distances) and ease of use. They also have high thermal mass (the ability to store and release heat), if the bricks are a minimum of 300mm thick.
Earth buildings have excellent fire ratings which makes them suitable for building in bushfire prone areas and for the construction of fire rated walls within buildings. When designing new buildings consider using low pitched or curved roofs and parapet walls to reduce the impact of radiant heat and possibility of embers entering the roof area.
The ideal building material would be ‘borrowed’ from the environment and replaced after use. There would be little or no processing of the raw material and all the energy inputs would be directly, or indirectly, from the sun. This ideal material would also be cheap and would perform well thermally and acoustically. If used carefully, mud bricks come close to this ideal.
Basic mud bricks are made by mixing earth with water, placing the mixture into moulds and drying the bricks in the open air. Straw or other fibres that are strong in tension are often added to the bricks to help reduce cracking. Mud bricks are joined with a mud mortar and can be used to build walls, vaults and domes.
At its simplest, mud brick making places mud in moulds which, after initial drying, are removed to allow the bricks to dry slowly (not in direct sun). Moulds can be made from timber or metal — anything that can be shaped to provide the desired size for the bricks. Virtually all the energy input for mud brick construction is human labour (indirectly fuelled by the sun) and after a lifetime of use, the bricks break back down into the earth they came from.
The most effective use of mud bricks in building healthy, environmentally responsible houses comes from understanding their merits and accepting their limitations. Mud brick construction is often referred to as ‘adobe’ which is an Arabic and Berber word brought by Spaniards to the Americas, where it was adopted into English.
The use of earth construction is well established in energy efficient housing. Despite the fact that most of the world’s buildings are made of earth and it is one of the oldest known building materials, much about its properties and potential remains undeveloped and poorly researched.
Performance summaryAppearanceThe appearance of mud bricks reflects the materials they are made from. They are thus earthy, with their colour determined by the colour of clays and sands in the mix. Finished walls can range from a strong expression of the brick patterns to a smoothly continuous surface.
With thick enough walls, mud brick can create load bearing structures up to several storeys high. Vaults and domes in mud brick prove that it can be used for many situations other than vertical walls. It may be employed as infill in a timber frame building or for loadbearing walls, although its compressive strength is relatively low. Typically, Australian mud brick structures are single or double storey. In Yemen buildings eight storeys high and more have stood for centuries!
Mud brick walls provide high thermal mass. For most Australian climatic conditions, as a rule of thumb, walls should be a minimum of 300mm thick to provide effective thermal mass (see Thermal mass).
A well-built mud brick wall has very good sound insulation properties. In fact, it can be almost equivalent to a monolithic masonry structure in its capacity for sound attenuation (see Noise control). Some modern mud brick homes use mud brick for external walls and light partition walls internally; it is more effective for thermal and acoustic performance to use mud brick for the partition walls and lightweight, well-insulated external walls.
Fire and vermin resistanceSince earth does not burn, and earth walls do not readily provide habitat for vermin, mud brick walls generally have excellent fire and vermin resistance.
Durability and moisture resistanceMud brick walls are capable of providing structural support for centuries but they need protection from extreme weather (e.g. with deep eaves) or continuous maintenance: the ancient structures of the Yemen have been repaired continuously for the centuries they have been standing. Although some soils are very resistant to weathering, as a general rule mud brick needs protection from driving rain and should not be exposed to continuous high moisture.
Breathability and toxicityMud bricks make ‘breathable’ walls but some mud brick recipes include bitumen, which potentially results in some outgassing of hydrocarbons. Ideally earth should be used in, or as near as possible to, its natural state.
Environmental impactsMud bricks could have the lowest impact of all construction materials. Mud brick should not contain any organic matter — the bricks should be made from clays and sands and not include living soil. They require very little generated energy to manufacture, but large amounts of water. Their embodied energy content is potentially the lowest of all building materials but the use of additives such as cement, excessive transport and other mechanical energy use can increase the ‘delivered’ embodied energy of all earth construction (see Embodied energy).
In a similar way, the greenhouse gas emissions associated with unfired mud bricks can (and should) be very low. To keep emissions to an absolute minimum, the consumption of fossil fuel and other combustion processes have to be avoided. If, say, 5% cement is added to a 300mm mud brick wall, it makes a fairly high energy/high emission building material, close to the embodied energy of a 125mm unreinforced concrete wall.
The clay content of mud brick can range between 30% and 70% and overall earth content may also include silt, gravel and stones. There are a number of tests for suitability of the earth, and the approval process may require an erosion test. Before excavating for on-site mud, consider the site layout to minimise carrying and transport; ensure there is space to keep any topsoil separate for use on the garden.
A typical standard mud brick is 300–375mm long, 250–300mm wide and 125mm high, and can weigh up to 15kg. Mud bricks can be made in a range of sizes and moulds and can be made in special shapes for fitting around structural elements and accommodating pipes and wires.
Although mud brick can be loadbearing, there is also widespread use of frames. The advantages are that a roof structure can be erected for weather protection for both mud brick making and construction. Disadvantages include the need to connect with and build around frame structures.
After the footings have been placed and the bricks are ready for laying, the building process is similar to that of any other masonry construction.
All structural design should be prepared by a competent person and may require preparation or checking by a qualified engineer. Qualified professionals, architects and designers have years of experience and access to intellectual property, and can save house builders time and money as well as help ensure environmental performance. All masonry construction has to comply with the Building Code of Australia and Australian Standards. For example, all masonry walls are required to have movement/expansion joints at specified intervals.
Footings
It is possible to make footings from rubble, but unconventional construction may make it harder to obtain building approvals and the usual method is to employ strip or raft concrete footings. A raft concrete slab can make a clean, flat surface for making mud bricks. A damp proof course must be laid between the footings and brick wall to prevent rising damp. A ‘splash course’ of fired bricks is advisable to prevent erosion of the lower course of mud bricks from heavy rain.
Mud bricks can be load bearing but it is also usual Australian practice to build mud brick walls between timber or steel frames.
Load bearing mud brick wall construction requires particular attention to good bonding (avoiding continuous vertical joints) and ensuring stability by having returns on the walls that buttress them against sideways forces. Again, normal traditional masonry practice applies to the pattern in which bricks should be laid. It is possible to create arches, squinches and domes in mud brick; they have featured in adobe structures since time immemorial but are rare in modern buildings of this type.
Joints and connections Mud bricks are laid on thick mortar beds that are essentially the same mix as the brick, but in its ‘muddy’ state. Once dried, it can be difficult to distinguish between mortar bed and brick, and some adobe aesthetics exploit this ‘seamless’ appearance to create a monolithic effect. In loadbearing mud brick construction, roof structures bear on wall plates. In framed mud brick construction there may be timber or steel columns around which the mud brick walls are built. Considerable roof overhang is generally recommended to afford some protection to walls from driving rain. In more sheltered areas this requirement is less vital, but care must be taken to provide a good quality render and waterproofing finish (see ‘Finishes’ below).
Walls are laid in the traditional manner of masonry with string lines to provide a guide to vertical and horizontal alignments.
The mud mortar beds are normally quite thick and need to provide complete bedding for the bricks. Perpends are similarly thick (about 20–30mm). The intention is to produce a wall that is effectively monolithic, i.e. as if it were a single piece of material.
Fixings to mud brick need to allow for the relatively poor ‘pull-out’ strength of the material. Strong fixings can be achieved by embedding dowels or plugs into a wall — the depth and type of which should be determined by reference to a skilled builder or engineer if the load carrying capacity of the fixing is critical.
Openings Lintels can be in any structurally appropriate material, although timber is typically used. Beams and lintels can be formed from quite ‘rough and ready’ timber and readily blended into the mud brick construction. Mud bricks can be also be laid to form arches, particularly over small spans (less than a metre), and even domes, although this requires high levels of bricklaying skills as well as more stringent demands from engineering and approvals processes.
FinishesAfter brushing to get a fairly even surface, the final finish is a mud slurry, typically completed by hand. This slurry may also be the final waterproofing coat (e.g. a mud and cow dung mix) or it may have a further clear coat of proprietary waterproofing material.
Linseed oil and turpentine can also be used as a final finish — and can be a very effective method of protecting walls susceptible to erosion. There is even the option of using the natural plastic of cellulose, processed by cattle, to create mud and manure slurry, although this is seldom employed in Australia. Finishes can range from rustic to smooth, with this flexibility of approach being one of the material’s many appealing qualities.
Cob, wattle and daub, earth render Cob is an ancient earth building technique of mixing earth, sand, gravel or pebbles and straw with a little water. It requires minimal construction skills and may be the world’s most common building material.
Cob walls are built without formwork by placing lumps of the cob mix by hand to make massive walls, typically 450–600mm thick, built up in layers. Each layer needs to dry out sufficiently to support the next. It lends itself to making free-flowing sculptural forms.
This high thermal mass material has some insulation value. Cob building depends upon wall thickness for its structural and environmental performance. Cob is fireproof and can be used to make stoves, fireplaces and chimneys.
Cob walls require firm footings to avoid movement and cracking and to keep the base of the walls dry. They need to be whitewashed (lime and water) for weather protection.
Wattle and daub consists of panels of woven timber lattice set in timber frames. The wattle was traditionally made from wood coppiced from trees that would continually regenerate branches for future harvesting. The panels are daubed with a mud and straw mixture up to a thickness of 50–150mm. As with all earth constructions, wattle and daub walls need sealing against the weather with a breathable finish such as whitewash.
Earth render is fundamentally a mud or clay slurry that is reinforced with straw or cow dung. It can be applied to mud brick or cob walls and can be used to render straw bale walls.
These very old techniques that date back to the earliest days of building are quite uncommon in the modern era. If you are contemplating using these methods it is worth checking out the growing number of websites and networks through which people exchange information and experience.
All earth walls benefit from being protected by wide, overhanging roofs that prevent driving rain from eroding their surface.
At Earth homes, we specialise in building custom designed, beautiful mud brick homes to suit your chosen block. Sometimes, the block already has a house on it. We can either work with the existing structure and extend and renovate, or we can remove the home and start from scratch.
Building with heavy materials such as mud bricks, requires suitable footings such as a course of regular kiln fired bricks or concrete footings. They are held together with a mud mortar mixture which is similar in composition to the mud brick mixture itself. Mud bricks, being soft and un-fired, are easy to cut with hand tools, and can be formed into interesting shapes.
Once laying of the bricks is finished and the mortar is dry, the brick walls are often rendered with mud-based renders, although many mud brick walls are left natural, or are sealed with a transparent water-based sealant to improve weather resistance.
Mudbricks have many advantages, including low cost and low embodied energy (especially if they are made on site and not transported long distances) and ease of use. They also have high thermal mass (the ability to store and release heat), if the bricks are a minimum of 300mm thick.
Earth buildings have excellent fire ratings which makes them suitable for building in bushfire prone areas and for the construction of fire rated walls within buildings. When designing new buildings consider using low pitched or curved roofs and parapet walls to reduce the impact of radiant heat and possibility of embers entering the roof area.
The ideal building material would be ‘borrowed’ from the environment and replaced after use. There would be little or no processing of the raw material and all the energy inputs would be directly, or indirectly, from the sun. This ideal material would also be cheap and would perform well thermally and acoustically. If used carefully, mud bricks come close to this ideal.
Basic mud bricks are made by mixing earth with water, placing the mixture into moulds and drying the bricks in the open air. Straw or other fibres that are strong in tension are often added to the bricks to help reduce cracking. Mud bricks are joined with a mud mortar and can be used to build walls, vaults and domes.
At its simplest, mud brick making places mud in moulds which, after initial drying, are removed to allow the bricks to dry slowly (not in direct sun). Moulds can be made from timber or metal — anything that can be shaped to provide the desired size for the bricks. Virtually all the energy input for mud brick construction is human labour (indirectly fuelled by the sun) and after a lifetime of use, the bricks break back down into the earth they came from.
The most effective use of mud bricks in building healthy, environmentally responsible houses comes from understanding their merits and accepting their limitations. Mud brick construction is often referred to as ‘adobe’ which is an Arabic and Berber word brought by Spaniards to the Americas, where it was adopted into English.
The use of earth construction is well established in energy efficient housing. Despite the fact that most of the world’s buildings are made of earth and it is one of the oldest known building materials, much about its properties and potential remains undeveloped and poorly researched.
Performance summaryAppearanceThe appearance of mud bricks reflects the materials they are made from. They are thus earthy, with their colour determined by the colour of clays and sands in the mix. Finished walls can range from a strong expression of the brick patterns to a smoothly continuous surface.
With thick enough walls, mud brick can create load bearing structures up to several storeys high. Vaults and domes in mud brick prove that it can be used for many situations other than vertical walls. It may be employed as infill in a timber frame building or for loadbearing walls, although its compressive strength is relatively low. Typically, Australian mud brick structures are single or double storey. In Yemen buildings eight storeys high and more have stood for centuries!
Mud brick walls provide high thermal mass. For most Australian climatic conditions, as a rule of thumb, walls should be a minimum of 300mm thick to provide effective thermal mass (see Thermal mass).
A well-built mud brick wall has very good sound insulation properties. In fact, it can be almost equivalent to a monolithic masonry structure in its capacity for sound attenuation (see Noise control). Some modern mud brick homes use mud brick for external walls and light partition walls internally; it is more effective for thermal and acoustic performance to use mud brick for the partition walls and lightweight, well-insulated external walls.
Fire and vermin resistanceSince earth does not burn, and earth walls do not readily provide habitat for vermin, mud brick walls generally have excellent fire and vermin resistance.
Durability and moisture resistanceMud brick walls are capable of providing structural support for centuries but they need protection from extreme weather (e.g. with deep eaves) or continuous maintenance: the ancient structures of the Yemen have been repaired continuously for the centuries they have been standing. Although some soils are very resistant to weathering, as a general rule mud brick needs protection from driving rain and should not be exposed to continuous high moisture.
Breathability and toxicityMud bricks make ‘breathable’ walls but some mud brick recipes include bitumen, which potentially results in some outgassing of hydrocarbons. Ideally earth should be used in, or as near as possible to, its natural state.
Environmental impactsMud bricks could have the lowest impact of all construction materials. Mud brick should not contain any organic matter — the bricks should be made from clays and sands and not include living soil. They require very little generated energy to manufacture, but large amounts of water. Their embodied energy content is potentially the lowest of all building materials but the use of additives such as cement, excessive transport and other mechanical energy use can increase the ‘delivered’ embodied energy of all earth construction (see Embodied energy).
In a similar way, the greenhouse gas emissions associated with unfired mud bricks can (and should) be very low. To keep emissions to an absolute minimum, the consumption of fossil fuel and other combustion processes have to be avoided. If, say, 5% cement is added to a 300mm mud brick wall, it makes a fairly high energy/high emission building material, close to the embodied energy of a 125mm unreinforced concrete wall.
The clay content of mud brick can range between 30% and 70% and overall earth content may also include silt, gravel and stones. There are a number of tests for suitability of the earth, and the approval process may require an erosion test. Before excavating for on-site mud, consider the site layout to minimise carrying and transport; ensure there is space to keep any topsoil separate for use on the garden.
A typical standard mud brick is 300–375mm long, 250–300mm wide and 125mm high, and can weigh up to 15kg. Mud bricks can be made in a range of sizes and moulds and can be made in special shapes for fitting around structural elements and accommodating pipes and wires.
Although mud brick can be loadbearing, there is also widespread use of frames. The advantages are that a roof structure can be erected for weather protection for both mud brick making and construction. Disadvantages include the need to connect with and build around frame structures.
After the footings have been placed and the bricks are ready for laying, the building process is similar to that of any other masonry construction.
All structural design should be prepared by a competent person and may require preparation or checking by a qualified engineer. Qualified professionals, architects and designers have years of experience and access to intellectual property, and can save house builders time and money as well as help ensure environmental performance. All masonry construction has to comply with the Building Code of Australia and Australian Standards. For example, all masonry walls are required to have movement/expansion joints at specified intervals.
Footings
It is possible to make footings from rubble, but unconventional construction may make it harder to obtain building approvals and the usual method is to employ strip or raft concrete footings. A raft concrete slab can make a clean, flat surface for making mud bricks. A damp proof course must be laid between the footings and brick wall to prevent rising damp. A ‘splash course’ of fired bricks is advisable to prevent erosion of the lower course of mud bricks from heavy rain.
Mud bricks can be load bearing but it is also usual Australian practice to build mud brick walls between timber or steel frames.
Load bearing mud brick wall construction requires particular attention to good bonding (avoiding continuous vertical joints) and ensuring stability by having returns on the walls that buttress them against sideways forces. Again, normal traditional masonry practice applies to the pattern in which bricks should be laid. It is possible to create arches, squinches and domes in mud brick; they have featured in adobe structures since time immemorial but are rare in modern buildings of this type.
Joints and connections Mud bricks are laid on thick mortar beds that are essentially the same mix as the brick, but in its ‘muddy’ state. Once dried, it can be difficult to distinguish between mortar bed and brick, and some adobe aesthetics exploit this ‘seamless’ appearance to create a monolithic effect. In loadbearing mud brick construction, roof structures bear on wall plates. In framed mud brick construction there may be timber or steel columns around which the mud brick walls are built. Considerable roof overhang is generally recommended to afford some protection to walls from driving rain. In more sheltered areas this requirement is less vital, but care must be taken to provide a good quality render and waterproofing finish (see ‘Finishes’ below).
Walls are laid in the traditional manner of masonry with string lines to provide a guide to vertical and horizontal alignments.
The mud mortar beds are normally quite thick and need to provide complete bedding for the bricks. Perpends are similarly thick (about 20–30mm). The intention is to produce a wall that is effectively monolithic, i.e. as if it were a single piece of material.
Fixings to mud brick need to allow for the relatively poor ‘pull-out’ strength of the material. Strong fixings can be achieved by embedding dowels or plugs into a wall — the depth and type of which should be determined by reference to a skilled builder or engineer if the load carrying capacity of the fixing is critical.
Openings Lintels can be in any structurally appropriate material, although timber is typically used. Beams and lintels can be formed from quite ‘rough and ready’ timber and readily blended into the mud brick construction. Mud bricks can be also be laid to form arches, particularly over small spans (less than a metre), and even domes, although this requires high levels of bricklaying skills as well as more stringent demands from engineering and approvals processes.
FinishesAfter brushing to get a fairly even surface, the final finish is a mud slurry, typically completed by hand. This slurry may also be the final waterproofing coat (e.g. a mud and cow dung mix) or it may have a further clear coat of proprietary waterproofing material.
Linseed oil and turpentine can also be used as a final finish — and can be a very effective method of protecting walls susceptible to erosion. There is even the option of using the natural plastic of cellulose, processed by cattle, to create mud and manure slurry, although this is seldom employed in Australia. Finishes can range from rustic to smooth, with this flexibility of approach being one of the material’s many appealing qualities.
Cob, wattle and daub, earth render Cob is an ancient earth building technique of mixing earth, sand, gravel or pebbles and straw with a little water. It requires minimal construction skills and may be the world’s most common building material.
Cob walls are built without formwork by placing lumps of the cob mix by hand to make massive walls, typically 450–600mm thick, built up in layers. Each layer needs to dry out sufficiently to support the next. It lends itself to making free-flowing sculptural forms.
This high thermal mass material has some insulation value. Cob building depends upon wall thickness for its structural and environmental performance. Cob is fireproof and can be used to make stoves, fireplaces and chimneys.
Cob walls require firm footings to avoid movement and cracking and to keep the base of the walls dry. They need to be whitewashed (lime and water) for weather protection.
Wattle and daub consists of panels of woven timber lattice set in timber frames. The wattle was traditionally made from wood coppiced from trees that would continually regenerate branches for future harvesting. The panels are daubed with a mud and straw mixture up to a thickness of 50–150mm. As with all earth constructions, wattle and daub walls need sealing against the weather with a breathable finish such as whitewash.
Earth render is fundamentally a mud or clay slurry that is reinforced with straw or cow dung. It can be applied to mud brick or cob walls and can be used to render straw bale walls.
These very old techniques that date back to the earliest days of building are quite uncommon in the modern era. If you are contemplating using these methods it is worth checking out the growing number of websites and networks through which people exchange information and experience.
All earth walls benefit from being protected by wide, overhanging roofs that prevent driving rain from eroding their surface.
At Earth homes, we specialise in building custom designed, beautiful mud brick homes to suit your chosen block. Sometimes, the block already has a house on it. We can either work with the existing structure and extend and renovate, or we can remove the home and start from scratch.