Quick Answer
Improve the insulation of your rammed earth walls by applying a 2-3 inch thick layer of natural insulating materials such as straw bales, recycled denim, or shredded newspaper between the rammed earth and a 1/4 inch thick layer of exterior plaster.
Insulation Materials and Techniques
To improve the insulation of your rammed earth walls, consider using natural materials that are breathable, non-toxic, and eco-friendly. A good option is to use a 2-3 inch thick layer of straw bales, which can provide R-20 insulation ratings when properly installed. Another option is to use recycled denim insulation, which has a R-13 insulation rating and can be easily installed between the rammed earth and a 1/4 inch thick layer of exterior plaster.
Exterior Plaster and Formwork
A well-designed exterior plaster system can help improve the insulation of your rammed earth walls by preventing heat transfer and moisture penetration. To achieve this, use a 1/4 inch thick layer of exterior plaster made from a mixture of lime, sand, and water. Additionally, design your formwork to include a 2-4 inch gap between the rammed earth and the exterior plaster to allow for expansion and contraction.
Thermal Mass and Soil Mix
To maximize the thermal mass of your rammed earth walls, use a soil mix that includes a high percentage of sand and gravel. A mix with a 10-20% sand content can provide excellent thermal mass, while a mix with a 20-30% sand content can provide even better performance in desert and arid climates. Additionally, consider using a soil mix that includes a natural admixture such as bentonite or kaolin, which can help improve the thermal mass and durability of the rammed earth walls.
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