Rammed earth frequently asked questions
What is Stabilised Rammed Earth?
Stabilised Rammed Earth is a mixture of gravel, sand, clay and small portion of cement plus a waterproof additive, engineered and rammed to create an extremely strong and durable wall system, we have achieved 19 Mpa with a recent compression test. The thickness is generally 300mm Standard or 400mm, insulated. Stabilised rammed earth walls are dense, solid, and stone-like with great environmental benefits, fire proof and superior low maintenance characteristics. Wall systems can be as high as 10 metres.
What about the building code?
Generally, Tasmanian councils want a 6 star rating plus the stamped approval of a Structural Engineer and a Building Surveyor, After that you apply for a building permit and follow the same rules that others do when dealing with the council building inspector. we personally recommend Aldanmark Engineering they specialise in Rammed Earth Construction.
How much does it cost?
The initial cost of rammed earth construction is comparable to conventional construction, primary factors affecting the cost of any project are design and site characteristics. long term there is no painting required and you will save a heap on your heating/cooling costs
Can I use soil on my property
Generally we use quarried gravels and sand as the labour cost of cleaning and testing on site soil can be expensive, plus most of the time it is unsuitable and really the soil cost is only a small part of the overall price of the wall system
Rammed earth energy rating
Insulated rammed earth walls start with an R-value of 2.49 using 50mm xps foam rigid board in the centre of a 400mm thick wall keeping the heat in and the cold out. You can increase it to R 4.3 by using 100mm xps board and 450mm thick walls.
One of the most important aspects of a rammed earth wall that is over looked with the current energy rating system is the thermal mass; a 300mm thick rammed earth wall can store heat energy up to 12 hours, which can help stabilize the indoor air temperature during winter.
Clients do not necessarily have to spend extra dollars on insulated rammed earth walls. With good design and performance glazing, a house with uninsulated rammed earth construction can easily satisfy the requirements of the Building Code of Australia.
Recently we got a 6 star rating on a two story rammed earth house at Beaumaris on the East Coast of Tasmania. All the rammed earth walls are uninsulated and 300mm thick, we achieving six stars by having a concrete slab, double glazed timber windows an thick insulation in the ceiling. The home faces the southeast!
Using thermal calculation, a building is compliant if it does not exceed an annual energy allowance, and the energy usage of the building is given a star rating of up to ten stars. A building passing with a star rating is not obliged to match all the acceptable construction provisions of the Deemed-to-Satisfy energy efficiency provisions, as the star rating shows that the building achieves the required overall thermal performance. A thermal calculation can be produced using software which is accredited for this purpose.
or Paul at Building Evaluate Hobart Phone 0419 312 558 Email firstname.lastname@example.org
Do you seal rammed earth walls?
A waterbased slicone admixture is used with the initial mixing process and/or clear surface coatings can be applied to walls if needed
How durable is rammed earth?
One of the oldest rammed earth buildings in Australia still in use is located at Richmond Tasmania, Mrs.Curries bed & breakfast circa 1820-1850 with no cement, so with stabilized earth construction (where you use cement as the glue) we have compression tested samples blocks and we are getting around 15mpa, so one can only imagine how long a wall system would last.
Do you add oxides to the walls
Yes we have added oxides to make different colour systems
Will rammed earth help make my house carbon neutral?
Rammed earth structures have a small carbon foot print. Where possible local materials are generally used, plus a little cement, and very little waste, compared to other forms of construction it is built with low embodied energy. Humidity levels in a rammed earth house stay between40% and 60% which an ideal range for asthma sufferers. Rammed earth walls also will "breathe" more than concrete structures, avoiding condensation issues without significant heat loss and will have a significant contribution to the overall energy-efficiency of a building.
For more information, please email or telephone Chris on 0417589089