A Guide to Rammed Earth Construction
Know why and how to build your home out of the most abundantly available natural material on the planet
Rammed earth construction, as the name suggests, is a way of building structures by ramming or packing earth (soil). Just like mother nature creates sedimentary rocks by natural compaction and cementation of soil, rammed earth structures are built by manual compaction of aggregates such as sand, soil and clay within a formwork mould.
Although the monolithic nature of a traditional rammed earth unit gives it the required durability and strength, an advanced version is ‘stabilised’ rammed earth construction which involves the addition of a small amount of cement to the soil mixture for extra stability and resistance.
Thanks to rammed earth’s organic, timeless appearance, sustainability aspects and cost-effectiveness, it can be associated with various design strategies and interior design styles. Let us dig deeper and read about all the features and construction methodology of this down-to-earth technique, topped with insights and advice from a architect Anant Mairal.
Although the monolithic nature of a traditional rammed earth unit gives it the required durability and strength, an advanced version is ‘stabilised’ rammed earth construction which involves the addition of a small amount of cement to the soil mixture for extra stability and resistance.
Thanks to rammed earth’s organic, timeless appearance, sustainability aspects and cost-effectiveness, it can be associated with various design strategies and interior design styles. Let us dig deeper and read about all the features and construction methodology of this down-to-earth technique, topped with insights and advice from a architect Anant Mairal.
Living in a rammed earth home is a comfortable and guilt-free experience. Why so?
- Rammed earth walls absorb heat during the day and release it during the night due to their high thermal mass. This helps to maintain a stable and favourable temperature inside, without relying and spending on cooling and heating devices.
- Rammed earth walls’ porous, breathable surfaces absorb excess moisture and release it when the air is dry, to auto-regulate the humidity level inside the home at all times.
- Rammed earth is non-combustible. Hence, the structures turn out highly fire-resistant.
- Rammed earth is non-toxic and non-polluting due to its natural composition and basic construction process.
- Rammed earth walls’ thick massing makes them extremely sound-proof; they are termite-resistant as well.
How are rammed earth structures made?
- A sample of the subsoil is collected from the site. Simple field tests are done to determine the composition of the soil and decide on the additives needed to prepare the soil. A typically good soil for rammed earth construction has approximately 50 per cent sand, 20 per cent gravel, 15 per cent clay and 15 per cent silt. If the available soil is not fit for use, the same can procured from a local vendor.
- Next, 6–8 per cent (by mass) of cement is added to the soil mix for building a stabilised rammed earth unit.
- Once the soil mix is ready, it is watered to attain the desired moisture content. A sample of the mixture is compacted by hand to check its ability to hold shape.
- Next, shutters or formwork panels (can be made of wood or metal) are raised and fixed upright on the site as per the thickness and height of the wall to be built. The shutters are coated with oil or diesel for easy removal later.
- Once the formwork is fixed, a layer of the moistened soil mix is dropped inside and compressed manually with rammers to achieve a 50 to 60 per cent compaction.
- The process is repeated until the formwork mould is completely filled.
Architect Anant Mairal is currently practising earth architecture at Auroville in Puducherry.
He says, “Provision for electrical conduits, pipelines, fenestration and so on can be provided during the fixing of formwork. Mechanical or electrical rammers can be employed to improve efficiency. However, I prefer to buy time and employ local labour for the compacting job. The formwork shutters are typically removed the next day and the structure is cured for 14 days. Depending upon the application and site conditions, the rammed earth structure needs to be protected from the top (with capping) and bottom (with plinth reinforcement) to achieve a tough unit that doubtlessly stands the test of time.”
Find an architect on Houzz here
He says, “Provision for electrical conduits, pipelines, fenestration and so on can be provided during the fixing of formwork. Mechanical or electrical rammers can be employed to improve efficiency. However, I prefer to buy time and employ local labour for the compacting job. The formwork shutters are typically removed the next day and the structure is cured for 14 days. Depending upon the application and site conditions, the rammed earth structure needs to be protected from the top (with capping) and bottom (with plinth reinforcement) to achieve a tough unit that doubtlessly stands the test of time.”
Find an architect on Houzz here
How is rammed earth construction good for the community?
This form of construction is environmentally low-impact while being labour-intensive. A large part of the total energy, cost and time is used in extracting, transporting, mixing and ramming of the materials, rather than in manufacture of the components. While quarrying of the subsoil from the site itself reduces energy consumption even more, the reusability of the formwork shutters makes it an economical and cost-effective construction process. Being labour-intensive, it provides employment to more of the local work force.
Mairal points out, “Rammed earth construction is proven to have a very low environmental impact owning to the source and type of materials used. Apart from that, it has the power to add social value to the local community with employment generation and skill development.” He elaborates, “Unlike concrete and steel construction, the cost of material is less than the cost of labour in rammed earth construction. This lets us distribute the amount among the locals, thereby improving lives at large.”
Lessons From Earth Architecture in Auroville
This form of construction is environmentally low-impact while being labour-intensive. A large part of the total energy, cost and time is used in extracting, transporting, mixing and ramming of the materials, rather than in manufacture of the components. While quarrying of the subsoil from the site itself reduces energy consumption even more, the reusability of the formwork shutters makes it an economical and cost-effective construction process. Being labour-intensive, it provides employment to more of the local work force.
Mairal points out, “Rammed earth construction is proven to have a very low environmental impact owning to the source and type of materials used. Apart from that, it has the power to add social value to the local community with employment generation and skill development.” He elaborates, “Unlike concrete and steel construction, the cost of material is less than the cost of labour in rammed earth construction. This lets us distribute the amount among the locals, thereby improving lives at large.”
Lessons From Earth Architecture in Auroville
What are the aesthetic aspects of rammed earth?
Rammed earth walls take up the colour of the soil of which they are made up. The natural colour and the organic sturdiness can make one feel closer to the nature, thereby inducing the effect of warmth and security.
“One of the best things about rammed earth construction,” Mairal says, “is it allows us to eliminate a number of layers of processing to achieve a finished result. The soil mix alone offers a unique exterior surface and interior finish, thereby ruling out the need to plaster and paint the wall. Although rammed earth walls can be treated externally to pull off other finishes, I personally adore the tactile, natural look of the layered pattern.”
Rammed-Earth Walls: The Next Big Thing?
Rammed earth walls take up the colour of the soil of which they are made up. The natural colour and the organic sturdiness can make one feel closer to the nature, thereby inducing the effect of warmth and security.
“One of the best things about rammed earth construction,” Mairal says, “is it allows us to eliminate a number of layers of processing to achieve a finished result. The soil mix alone offers a unique exterior surface and interior finish, thereby ruling out the need to plaster and paint the wall. Although rammed earth walls can be treated externally to pull off other finishes, I personally adore the tactile, natural look of the layered pattern.”
Rammed-Earth Walls: The Next Big Thing?
The bottom line
Lack of awareness of rammed earth construction and scarcity of skilled rammed earth labour across the country is still a concern. “One cubic metre of a typical rammed earth wall costs as low as Rs 7500 when the soil is extracted from the site and Rs 9500 when the soil is bought from a vendor. Despite its innumerable positive attributes, earth construction is yet to be given its share of employment and regulation. Once it is practised as a primary construction type, myths regarding earth’s cost-effectiveness, durability and maintenance can be rightly busted.” Mairal concludes.
Read more:
Global Snapshot: Thought-Provoking Sustainability Solutions
Tell us:
Would you use rammed earth for your next home renovation? Share your thoughts about this construction technology in Comments below.
Lack of awareness of rammed earth construction and scarcity of skilled rammed earth labour across the country is still a concern. “One cubic metre of a typical rammed earth wall costs as low as Rs 7500 when the soil is extracted from the site and Rs 9500 when the soil is bought from a vendor. Despite its innumerable positive attributes, earth construction is yet to be given its share of employment and regulation. Once it is practised as a primary construction type, myths regarding earth’s cost-effectiveness, durability and maintenance can be rightly busted.” Mairal concludes.
Read more:
Global Snapshot: Thought-Provoking Sustainability Solutions
Tell us:
Would you use rammed earth for your next home renovation? Share your thoughts about this construction technology in Comments below.