34 years of answering the same questions — here are the honest answers.
Questions & answers
Common questions
The material
What is stabilised rammed earth?
A mixture of gravel, sand, clay, a small portion of cement and a waterproof additive — engineered and rammed to create an extremely strong, durable wall. We have achieved 19 MPa with recent compression testing. Dense, solid, stone-like, fireproof and virtually maintenance-free. Wall systems can be as high as 10 metres.
Is rammed earth fireproof?
Yes — stabilised rammed earth is non-combustible and has excellent fire resistance. It does not burn, does not contribute to the spread of fire, and holds its structural integrity under extreme heat far better than timber framing.
Does rammed earth need painting or maintenance?
No painting required — ever. The natural earth surface is the finished surface. Stabilised rammed earth is dense and durable. Occasional cleaning is all that's needed. This is one of the great long-term cost advantages of the material.
How strong is a rammed earth wall?
Very strong. Our recent compression tests have achieved 19 MPa — comparable to many concrete mixes. The walls are dense, solid and stone-like, with excellent structural performance.
Energy & thermal performance
What energy rating can rammed earth achieve?
A 6 star rating is achievable with both standard and insulated rammed earth. We recently achieved 6 stars on a two-storey home at Beaumaris on the East Coast — all 300mm uninsulated walls, southeast-facing — using a concrete slab, double glazed timber windows and thick ceiling insulation. Good design and quality glazing matter as much as the wall specification.
What is the thermal mass benefit?
A 300mm rammed earth wall can store heat energy for up to 12 hours — absorbing warmth during the day and releasing it overnight. This stabilises indoor temperatures in a way that lightweight construction simply cannot replicate. The current energy rating system doesn't fully capture this benefit, which is why rammed earth buildings often perform better in practice than their star rating suggests.
Do I need insulated walls to get a good energy rating?
Not necessarily. Clients do not have to spend extra on insulated walls. With good design, north-facing orientation and quality double glazing, standard 300mm uninsulated rammed earth can easily satisfy the Building Code of Australia. Insulated walls are most valuable for south-facing walls, heavily shaded buildings, or very cold climate zones. Call Chris to discuss what's right for your specific site.
What R-values do insulated walls achieve?
Our insulated system starts at R2.49 with a 50mm XPS core in a 400mm wall, and reaches R4.3 with a 100mm XPS core in a 450mm wall. The foam core is placed at the centre of the wall during construction, fully encased in rammed earth on both sides.
Construction & cost
How much does rammed earth construction cost?
The initial cost of rammed earth construction is comparable to conventional construction. Primary factors affecting the cost are design and site characteristics. Long term there is no painting required and you will save significantly on heating and cooling costs. The material pays for itself over time.
Can you use soil from my property?
Generally we use quarried gravels and sands. The labour cost of testing and cleaning on-site soil is expensive, and most site soils are unsuitable. The material cost is only a small part of the overall wall system price — so quarried material is almost always the better option both practically and economically.
How high can rammed earth walls be built?
Wall systems can be as high as 10 metres. We have built walls across that full range — from low garden walls to two-storey residential and commercial buildings.
Do you build anywhere in Tasmania?
Yes. We have extensive knowledge of soils and gravels right around Tasmania and can source material and build anywhere on the island. Distance is not a barrier — call Chris to discuss your location.
Approvals & building code
What does the building code require for rammed earth in Tasmania?
Tasmanian councils generally require a 6 star energy rating, plus stamped approval from a Structural Engineer and Building Surveyor, followed by a standard building permit. After that you follow the same process as any other construction — council building inspector and standard compliance. We personally recommend Aldanmark Engineering — they specialise in rammed earth construction.
Do you supply engineering drawings?
Yes — we supply detailed engineering drawings for insulated wall systems and lintels. These are ready for your building surveyor and structural engineer, and simplify the permit process considerably.