Quick Answer
Rammed earth walls typically provide moderate sound insulation, equivalent to a standard hollow concrete block wall, with a sound transmission class (STC) rating of around 35-45. This may not be sufficient for homes in noisy urban areas, but can be effective in quieter desert or arid climates where wind and external noise levels are lower.
Sound Insulation in Rammed Earth Walls
Rammed earth walls are made by compacting a mixture of soil, sand, and sometimes gravel into a formwork structure. The density of the compacted earth can vary, but it typically ranges between 1.6 and 2.1 tons per cubic meter. A higher density wall will generally provide better sound insulation, but will also be more expensive to construct.
Techniques for Improving Sound Insulation in Rammed Earth Walls
To improve sound insulation in rammed earth walls, builders can use various techniques. One common approach is to build a secondary wall or partition within the main rammed earth wall, using materials like wood or drywall to create a gap between the two walls. This can increase the STC rating to around 55-65. Another technique is to use a “double-layer” rammed earth construction, where two layers of earth are built on top of each other, separated by a thin layer of insulation. This can increase the STC rating to around 70-80.
Thermal Mass and Sound Insulation
Rammed earth walls also offer thermal mass benefits, which can help to reduce heat transfer between the interior and exterior of the building. However, in desert and arid climates, thermal mass can sometimes work against sound insulation, as the thermal massing effect can cause the wall to expand and contract, potentially increasing sound transmission. To mitigate this effect, builders can use techniques like thermal bridging breaks or insulated wall ties to minimize the thermal massing effect and improve sound insulation.
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