Rammed-Earth Walls: The Next Big Thing?
Rammed earth has natural warmth and beauty, plus the benefits of sustainability, durability and fire-resistance
Rammed earth is a construction technique that has been around for thousands of years and makes up long stretches of the Great Wall of China, the magnificent Kasbahs of Morocco and the enchanting Alhambra in Spain. It is also increasingly seen in contemporary architecture, revived as a sustainable building material for residential housing. The renewed interest in rammed earth walls is due to its thermal mass, strength, durability and visual impressiveness. Rammed-earth houses also have natural warmth and beauty that help tie them to the land and natural environment. Here, we lay the groundwork in this guide to rammed-earth walls in residential architecture.
Stabilised rammed-earth walls
Most modern rammed-earth walls are stabilised rammed earth. This means a small amount of cement is added to the traditional mixture for increased strength and durability. They are also usually coated with an air-permeable sealer to increase longevity. Stabilised rammed-earth walls are typically 300 millimetres thick for external walls and 200 or 300 millimetres thick for internal walls.
Browse through images of rammed earth walls
Most modern rammed-earth walls are stabilised rammed earth. This means a small amount of cement is added to the traditional mixture for increased strength and durability. They are also usually coated with an air-permeable sealer to increase longevity. Stabilised rammed-earth walls are typically 300 millimetres thick for external walls and 200 or 300 millimetres thick for internal walls.
Browse through images of rammed earth walls
This house on the Mornington Peninsula in Victoria, Australia has 300-millimetre-thick stabilised rammed-earth walls, with no finish. The wall acts as a spine in the house, providing a strong visual element and thermal mass, which helps maintain a comfortable stable internal temperature throughout the year.
Insulated stabilised earth
Rammed earth has limited thermal insulating qualities. However, insulated rammed-earth walls – 400-millimetres-plus thick with a 50-millimetre styrofoam insert – can achieve higher R-value levels and are used more commonly for external walls. R-value is a material’s resistance to conductive heat flow and is measured in terms of its thermal resistance. The higher the R-value, the greater the insulating effectiveness.
Rammed earth has limited thermal insulating qualities. However, insulated rammed-earth walls – 400-millimetres-plus thick with a 50-millimetre styrofoam insert – can achieve higher R-value levels and are used more commonly for external walls. R-value is a material’s resistance to conductive heat flow and is measured in terms of its thermal resistance. The higher the R-value, the greater the insulating effectiveness.
Appearance of rammed-earth walls
The natural materials used in the mixture will determine the colour of rammed-earth walls. Materials are often sourced locally to help buildings blend into their local environments, particularly in rural settings. Rammed-earth walls are typically cream, sand-coloured, peach, light tan or grey through to deep red.
See how this Bangalore home embraces an earthy palette
The natural materials used in the mixture will determine the colour of rammed-earth walls. Materials are often sourced locally to help buildings blend into their local environments, particularly in rural settings. Rammed-earth walls are typically cream, sand-coloured, peach, light tan or grey through to deep red.
See how this Bangalore home embraces an earthy palette
These 12 rammed-earth apartments have been dug into a sand hill, and the 230-metre-long rammed-earth wall is made from local soil and gravel. The iron-rich and sandy soil was extracted from local clay pans, along with pebbles and gravel quarried from the river bed. The result is a colour palette that blends seamlessly into the landscape.
The ramming process, done layer by layer, can introduce the effect of horizontal or stratified lines that can be used as a feature or removed altogether. Additionally, natural iron-oxide pigments can be introduced to influence the desired colour, and stones can be exposed or incorporated as features or for special effect. The texture and shaping of the formwork will also affect the final result.
Benefits of rammed-earth walls
Rammed earth is not recommended for tropical climates as walls can cause a house to hold too much heat.
- Excellent thermal mass
Rammed earth is not recommended for tropical climates as walls can cause a house to hold too much heat.
- Fire resistance
- Low maintenance
- Natural appeal
- Breathability
- Sound insulating
Learn all about acoustic panels
- Moisture-resistance
- Durability
Read more:
How Cool Architecture Can Combat Hot Summers
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Rammed-earth walls are constructed by ramming an aggregate mixture, including gravel, sand, silt and clay, between flat panels, frames or moulds (otherwise known as formwork). It is an on-site construction method, and removing the formwork reveals the rammed-earth wall.
Traditionally, a wooden pole was used to ram and compress the earth mixture. Today, a mechanical ram is used. Plumbing and electrical points are positioned internally as the walls are constructed.