Rammed Earth Construction
Rammed earth construction is one of the most ancient building techniques known, dating back many thousands of years. Earth has been the most fundamental and widely used building materials, employed to create strong and durable buildings throughout history.
Rammed earth walls are constructed by compacting an earth mixture into a framework of slats called a “form”, similar to those seen in concrete construction. This means that the architectural design of the finished building is governed by what shapes can be achieved by the form slats and components available. Doors, windows and other small openings can be constructed without lintels in stabilised walls, while custom forms can create arches and other specialised requirements.
The earth mixture is compacted in 100-200mm layers between the form slats with manual or pneumatic rammers, supported by concrete foundations. Walls are usually built in 2 meter sections, joined with rebates, reinforced by steel bars running through vertically.
No drying or curing is required, and the form can be disassembled immediately the earth has been compressed to the required degree and the section completed. Removing the form reveals a unique strata pattern on finished surface of the walls, a product of the tamping process.
Finished sections of wall are capped by a concrete beam, linking all segments of the wall together and adding extra structural support.
Once the earth walls and concrete work are completed, the timber frames are used to support floors, interior walls, and the roof. Earth walls are compatible with most conventional masonry components and fixings, and can be easily painted, plastered, or rendered as the design requires.
Rammed earth houses display great strength and durability, but also has excellent thermal properties – earth is naturally fireproof, but when densely packed, its high mass means it acts like a natural storage heater.
It absorbs heat from the outside environment, then radiates it back out as the atmospheric temperature drops, buffering and smoothing out variations in temperature, giving ongoing savings with heating costs.
The atmosphere in an earth house is unique and therefore it is important that the planning of an earth house should encompass the methods and maintenance required by the rammed earth construction process. The resulting natural strata look may also feature in the design, although surfaces can easily be applied if required.
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