Is it waterproof?
Yes, the rammed earth walls are waterproof and very suitable for a rainy climate. Rammed earth walls do not rot or decompose. In the earth mixture we’re adding a waterproofing admixture and exposed stabilised rammed earth (SRE) walls are capped to shed rainwater away from the wall surface.
A well-protected rammed earth building has a much higher resistance to rain than a wood frame home or other structures made of degradable materials.
What about insulation?
The 300mm thick SRE walls provide more effective thermal mass (U-Value) than any other comparatively priced wall system. SRE walls are now used in large commercial projects for this reason, saving many thousands of dollars on heating and air conditioning, as is otherwise the case in buildings designed using purely “R-Value” insulation principles.
What finishings are necessary?
Our walls have a unique off-form finish. The walls express sedimentary compaction lines that inform a simple and natural texture for which the material is famous. External wall surfaces are left untreated and allowed to “breathe” while internal surfaces are coated with a tough acrylic emulsion to reduce dust.
No finishings are required, however any standard finishings can be applied. Most architects choose rammed earth for the stunning aesthetics so we think it would be a shame to cover that up!
How much does it cost?
That varies from project to project, depending on project size, complexity of design and local material prices. Feel free to talk to us for a free initial consultation and quotation on your project.
What is included in the earth mix?
AsaDuru sources all the materials from local quarries nearby your project site. This is to ensure that the earth elements sourced will be homogenous, which is crucial to ensuring the correct blend required to make the property sufficiently robust.
The blend of the locally sourced quarried aggregates provide the bulk of the compacted density as well as the natural colours and textures of the walls. We test and analyse these materials for structural stability and density. We add between 8 to10 percent Portland grade cement to provide surface hardness and durability and sufficient water to gain optimum density during compaction.
We also use a silane/siloxane aqueous based waterproofing admixture called Plasticure which minimises water penetration and eliminates using external waterproofing coatings and future surface maintenance.
Why should you choose us as rammed earth subcontractor?
No other local rammed earth builder can bring the experience and track record of the Earth Structures Group of building over 1300 projects throughout the world over the past 30 years. Through the group partnership, we ensure a senior rammed earth supervisor with a minimum of 20 years experience of building modern rammed earth is present on each project.
How about piping and roofing?
These are generally done in the same way as for any other walling materials. All plumbing and fittings are placed within the formworks at the correct heights before constructing the walls.
How about maintenance?
Our walls are maintenance free. Each panel is constructed as a “fully articulated monolith” so stress fractures due to any shrinkage are eliminated. Like all solid masonry, the base of walls must be kept a minimum 50mm above the surrounding ground level to prevent rising damp, and the top surfaces of the walls require capping. We will provide you with these details early on so they can be incorporated into the design of the building.
Are the walls load bearing?
Our walls are load bearing so do not require additional portal frames. The massive structural panels add substantial bracing to the fabric of a building and can withstand significant point loads such as roof beams, verandah beams, floor beams and bracing beams. Your structural engineer should contact us for ideas and information as to how best to use the walls as structural elements.
Will pests be an issue?
Our walls have no timber portal frames or cavities and so are termite-proof. Door and window frames may require some protection though typically they are well above ground level and not prone to termite infestation.
What fire rating does your walls have?
Our walls have a 4 hour fire rating. The walls offer an ideal option for buildings in fire-prone areas.
What products do you offer?
We offer Stabilised rammed earth (SRE), Insulated stabilised earth (ISE) and Elevated stabilised earth (ESE).
The SRE wall panels are 300 or 400mm thick. They are ideal for internal walling or external walling that does not require a high R-value.
The ISE wall panels are 400mm thick with a 50mm Styrofoam panel set in the centre of the wall. Walls are structurally integrated using patented Earth Structures stainless steel bridging pins. These walls achieve a 2.48 R-value. They are useful for achieving higher external wall R-value levels.
The ESE wall panels are nominally 300mm thick. They are built as pre-rammed panels, designed similar to precast concrete panels to be elevated into difficult locations.
Tell me about the environmental benefits.
The massive monoliths that are our walls offer beautiful living environments while providing buildings with valuable thermal mass. Stabilised rammed earth (SRE) is one of the most sustainable materials available with around 70% reduction in embodied energy compared to fired bricks and a high thermal mass amongst other. SRE is recognised by both LEED and Living Building Challenge for its benefits (the Living Building Challenge is the world’s most rigorous proven performance standard for buildings).
Further benefits are: use of local materials, minimal waste during the construction phase (including low use of wood as our formwork system can be removed and reused), no firing process and thus no kilns, toxic emissions or greenhouse gases. No other walling can provide architects with such natural elegance combined with such low environmental impacts.
A well designed Earth Structures building can be managed without air conditioning in summer and with reduced heating input in winter. Many of our clients use only bedside or overhead fans when required in summer, combined with common sense opening and closing of doors and windows to maximise the passive solar benefits of living with high thermal mass walls.
We can explain these thermal benefits and how to effectively do away with much of our current reliance on air conditioners and heaters for a comfortable living environment.
Can you use soil from the site?
No. Site soil is prone to heaving or spalling when exposed to excessive weather conditions. The impact on the immediate landscape in excavating site material is also hazardous, often creating more costs than bringing the aggregate in from a local quarry.
We always source our aggregates from local quarries.
Tell me about the high thermal mass.
The high thermal mass of our minimum of 30 cm thick-rammed earth walls provides great protection from extremes in climates. The walls collect heat from the sun during daylight hours and release the warmth during the night, when the outside temperature sinks. The thermal mass of the walls makes for a very slow heat/cold penetration and allows the internal temperature to remain stable, with warmer feelings during the winter and cooler in the summer than outside temperatures.
It makes both an economic and environmental advantage to use locally sourced building materials instead of highly manufactured products.
Rammed earth: What does the process look like?
- Client requests rammed earth
- [Optional] An earth sample can be prepared. Cost will vary depending on site
- Client sends building designs to AsaDuru to give a quote
- AsaDuru delivers quote on the basis of local materials and equipment costs
- Client accepts quote
- AsaDuru carry out construction of walls delivering finished product
Rammed earth is constructed by mechanically packing earth mixture within a formwork, layer by layer (like the process sedimentary rocks go through during thousands of years, but here it’s done in the course of days). With Earth Structures Group extended track record over the past 30 years, we’re bringing a unique formwork system adapted to the rammed earth construction process together with substantial experience. Choosing the right material is half the challenge and one bad experience with a poor material can lead to unhappy consequences.
First, we source a suitable mixture of sand, gravel and clay from quarries near the site (to avoid excessive truck diesel) which is thoroughly tested for strength and colour before project start. The soil mix is then mixed with sufficient water to gain optimum density during compaction, 6-10% cement to provide surface hardness and durability, and a waterproofing additive before it is poured into our formwork. Within the formwork, the earth mixture is rammed in layers of around 10-15 cm, which are compressed to around 50% of their original height.
AsaDuru delivers rammed earth walls in an exclusive partnership with the Australia-based Earth Structures Group. The Earth Structures Group are pioneers and market leaders in the earth building industry, with an extensive track record of delivering over 1,300 projects in Australia, Europe and Asia over the past 30 years. Earth Structures Group is effectively a global company who are now able to direct and apply their experienced site supervisors wherever it is needed. This unique ability allows us to confidently apply the proven technique of Stabilised Rammed Earth in the African markets, thus providing the same high levels of quality & workmanship that has made it so successful in Australia and elsewhere. AsaDuru have exclusive rights to use Earth Structures’ proprietary formwork system within Africa.
Can I get any green building ratings?
Yes, using stabilised rammed earth for your project gives you the opportunity to get LEED points, BREEAM, Green Star rating, EDGE.
What makes an NZero home so special?
AsaDuru NZero is the modern low-impact rammed earth home that utilises rainwater harvesting, grey water system, wastewater treatment and renewable energy.
It is a home that minimises the environmental impacts in both the construction and the ongoing running of the building. It is a home that is both aesthetically beautiful and ecologically friendly.
NZero: What does the process look like?
We deliver NZero as sub-contractors. Instead of dealing with five different sub-contractors, we will be the one source of contact for each system.
From an end-user’s point of view:
- You secure your property.
- We will contact your own or one of AsaDuru’s partner architects & local builders and design a home according to your needs.
- We will visit the site and source appropriate materials from within your area.
- The local builder will build foundations and other ‘general’ elements. We install NZero to make your home come to life.
- You enjoy healthy and sustainable living with your family.