Can rammed earth walls be plastered for aesthetic purposes?

Preparing the Surface

Before applying a plaster, the rammed earth surface needs to be cured and stable. The ideal curing period is 28 days, but it can be accelerated by applying a breathable coating, like lime wash or a water-repellent treatment, as early as 14 days. This will help lock in moisture and prevent water damage to the wall.

Choosing the Right Plaster

Select a plaster that complements the earth tone of the rammed earth wall. A lime-based plaster is a popular choice, as it is breathable, durable, and allows the thermal mass of the earth wall to perform optimally. Mix the plaster with 1 part of lime to 2 parts of sand, and apply it in thin layers (about 1/8 inch or 3 mm) to prevent cracking.

Best Practices for Desert Climates

In arid climates, it’s crucial to seal the plastered surface to prevent water loss and damage from the elements. Apply a clear, breathable sealant, such as a mixture of beeswax and linseed oil, to the plastered surface. This will help protect the wall from wind-driven rain and intense sunlight while still allowing the wall to breathe.