Modern homes are often built so air-tight to provide good insulation that they don’t allow for fresh air to enter. Due to such things as off-gassing from paints, carpets, furniture, etc, the air inside the average American home is now often worse than the air outside.
Earth plasters, also called mud plaster and clay plaster, can play a role in creating a breathable home, i.e. walls that allow fresh air to slowly enter. Also called mud plaster and clay plaster, earth plasters are simply a mix of sand and clay and optional chopped straw. They’re powerful in their simplicity as they allow the walls to breathe, allowing toxic vapors to escape without any heat loss.
In this video, natural building expert Michael G. Smith of the Emerald Earth Sanctuary showed us the first and second coats of clay plaster being applied to a community center on the premises.