Breathing walls are very similar in structure to standard walls. However, whereas the passage of air and vapour through a standard wall is undesirable, and prevented by a water impermeable coating, it is promoted in breathing walls. This is achieved by using a structure which allows high permeability of moisture from the inside to the outside of the wall. There is no water impermeable layer, as would be found in standard walls. The wall is formed so that the resistance to inward flow is greater than that of outward moisture flow so that moisture diffuses naturally to the outside of the building.