Frequently Asked Questions
What is rammed earth?
Rammed earth is an earth based wall system made of compacted quarried earth, normally Class 3 aggregates that are extremely strong and durable. In modern rammed earth 8-10% cement is added as specified by an engineer. We can add rigid insulation panels within rammed earth walls for additional thermal resistance.
Quality rammed earth walls are dense, solid, and stone-like with great environmental benefits and superior low maintenance characteristics.
How much does it cost?
The initial cost of rammed earth construction is comparable to conventional solid masonry construction, however cost is considerably less in the long run. The average timber frame home has a life span of 49 years. A properly designed rammed earth house can easily sustain its integrity for 1000+ years, with substantial energy and maintenance savings for the life of the building.
Is rammed earth suitable for a rainy climate?
Yes, it is a very suitable type of building for a rainy climate. Rammed earth walls do not rot or decompose. Like any building, the most important aspects in protecting your building are the material of the wall system, roof design, strong foundation and good drainage.
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. Rammed earth homes routinely last for generations.
Can the walls be painted or plastered?
Yes, if you like but it is not necessary. The walls have an organic beauty in their raw form. Most people choose to leave the walls the colour of the earth used.
During construction, a hard low-sheen acrylic sealer is applied to all internal rammed earth walls to reduce dust.
What is Stabilised Rammed Earth?
Stabilised Rammed Earth is an environmentally friendly masonry wall material that looks and lasts like cut stone. It is the construction method of choice for environmentally conscious homeowners, architects and builders.
It is made from natural quarried aggregates, mixed with a small amount of stabiliser and pneumatically compacted within removable shuttering. When the formwork is removed, the walls are revealed with accurate spaces for windows, doorways, etc already pre-formed.
What sort of ‘earth’ can be used?
For Stabilised Rammed Earth to achieve its optimum strength and weather resistance, it must be made from an earth that has an assortment of particles that fit together like a jigsaw without leaving voids. The ideal earth for rammed earth building has been determined from numerous laboratory tests and confirmed by years of experience on site.
When well compacted, the right earth mixed with the correct amounts of stabiliser and water can achieve 98% density, which is virtually solid stone.
Can you use soil from the site for earth building?
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.
What is the correct terminology when discussing rammed earth construction?
These acronyms have eventuated over years of dealing with architects – so we want to stick with them!
SRE – Stabilized Rammed Earth
These walls are 300 or 400mm thick with high thermal mass. They are ideal for internal walling or external walling that does not require a high R-value.
ISE – Insulated Stabilised Earth
These walls are 400mm thick with a 50mm Styrofoam insert. 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.
ESE – Elevated Stabilised Earth
These are built as pre-rammed panels and lifted in place using technologies similar to concrete pre-cast panels, ideal for buildings with difficult access. The Earth Structures Group has developed pre-cast rammed earth technology to its current levels.
>What is the construction process for rammed earth buildings?
Planning & design
The Earth Structures Group works closely with homeowners, architects, engineers and builders on their rammed earth house plans to ensure we construct visually stunning buildings that are environmentally sustainable and stand the test of time.
We are passionate about rammed earth construction and only too pleased to provide information and support where we can.
Rammed earth walls are constructed using a blend of locally sourced road-base materials, sand, cement and waterproofing admixtures. We add enough water to achieve an optimum compacted density.
This blended material is then placed in 200mm layers within pre-set formwork and compacted using pneumatic rammers. The formwork is stripped the following day to reveal durable and beautiful off-form walls.
Services such as electrical and data conduits, plumbing pipes and vacuum ducts are placed as we go. These rammed earth panels are linked together using special control joint and lintel systems. Our staff will help explain the design and construction parameters required to achieve the best building outcome for you.
There is immense satisfaction turning stockpiles of earth into beautiful walls.
Once walls are completely detailed and properly dried, a hard low-sheen acrylic sealer is applied to all internal wall surfaces. External walls remain unsealed. Waterproofing admixtures combined with the density of the walls ensure driving rain will not penetrate wall surfaces.