The Dirt on Rammed Earth Construction – Is it a Good Option?
Rammed earth constructed buildings are gaining popularity in Australia, but are still relatively unknown to the wider community. If you have seen a building made with rammed earth, whilst you may not recognise the construction technique, you would have surely appreciated its beauty. Made with compacted earth, the walls have a natural colour, beauty and texture that is unique. Not only is the aesthetic aspect a feature but the size and thickness is also an architectural character.
The thickness of rammed earth walls is generally around 300 to 400 millimetres. Made from a mixture of soil, gravel, clay and sand, plus mixed with 5% stabilized rammed earth (SRE). A small amount of water is added before the formwork is completed. This is when the mixture is compressed between steel or timber forms with pneumatic rammers until it becomes somewhat like sedimentary rock. The finish is smooth and sharp. And the horizontal lines formed give the walls a distinct architectural aesthetic feel.
The colour of the rammed earth wall depends on the type of soil used. Naturally earthy tones are prominent and if another colour is desired, natural iron oxide can be added. This means a range of colours can be achieved which are all natural and non-toxic. Unlike plaster painted walls the colour is a part of the construction and does not chip or peel away. It is common for a clear sealer to be applied to prevent staining and dirt getting into the wall.
It is not an issue to have buildings made from rammed earth to be more than one storey in height or quite tall. The walls are very strong and can bear a lot of load. It is often the case that rammed earth structures are designed to be tall which showcases the architectural beauty of the walls themselves.
Rammed Earth Structures in Australia
A well known rammed earth building in Australia is the National Wine Centre in South Australia. Situated in the heart of the botanic gardens, this building is admired for its beauty and its rammed earth walls contribute to this architectural admiration.
A cattle ranch in Western Australia has the biggest rammed earth wall in the Southern Hemisphere. Luigi Rosselli Architects designed this wall for seasonal worker housing on the ranch. It is referred to as the ‘Great Wall of WA’ and is a fantastic example of the environmentally friendly building techniques rammed earth brings to the construction industry.
Another example of rammed earth architecture is the public toilets in Uluru. Quite fitting that the structure is made from natural materials, considering the landscape and beauty that surrounds this area.
Can Houses be built with Rammed Earth?
Residential homes are being built with rammed earth construction. A leading rammed earth construction company in Australia is ‘Earth Structures Group’, who have built close to one thousand residential homes. They work in this niche market of residential building in Australia and their website states;
‘We respect the investment our customers are making with us, and we provide the world’s best practice with our construction systems. We follow strict compliance codes set up within our group and are constantly striving to improve our methods.’
This addresses some of the limitations people have attributed to homes made with rammed earth. Insulation of rammed earth homes has been looked at to ensure it complies with modern energy star ratings in Australia. Good knowledge and planning of thermal mass must be part of the design process. The homes need to have insulation planning before construction. This means using passive solar design for the high thermal mass of rammed earth walls.
In some cases depending on the homes’ location and its position to the sun, extra insulation may need to be designed into the home. This is the reason why people use companies like Earth Structures Group, as they collaborate with architects due to their expertise with Rammed Earth. Meaning homes can be built with the best thermal benefits and not have to rely on constant use of air conditioners in Summer and heaters in Winter. They also comply with energy ratings in building regulations.
Making sure homes built with rammed earth achieve a good thermal rating will contribute to a rise in mainstream acceptance and knowledge. Not only will this appeal to environmentally aware home builders and owners, but energy conscious homeowners wanting to save on bills.
Just make sure you engage a builder that is experienced in rammed earth construction, design and planning.
Further reading https://www.earthstructuresgroup.com.au