Ideally earthen walls are finished with compatible earthen plasters on all internal surfaces. These can be finished decoratively to your taste and budget. A protective coating, however, is strongly recommended and a silicate-based paint (water-glass or ‘Keim’paint) is our material of choice. The chemical reaction with the mineral substrate hardens the surface, but allows the pores to remain open, keeping the walls fully breathing.The interior plaster can also be used on existing conventional walls to achieve a decorative finish and eliminate moisture problems, which can lead to mildew and health risks.nzeb design ltd. have developed a clay-based plaster range using natural pigments to create a variety of colourful finishes, including natural white. Like any earthen wall the light earth walls have to be protected from the weather on the outside. This can either be achieved by a traditional lime-based, three layered plaster painted with silicate-based mineral paint (Keim Granital), or any of the common new zealand cladding materials, providing a sufficient cavity is left behind it for ventilation.
With the protection of a professionally applied lime plaster there is no need for extreme overhangs that are required in other earthbuilding techniques in order to preserve exposed load - bearing earthen walls.
This makes it much easier to achieve a good passive solar design - let the sun in.