Along with paint an essential component of any breathing wall construction is an appropriate insulation. A breathing wall is a form of construction, generally timber frame, with high vapour permeability. This allows greater degree of moisture migration from inside to outside of a building.

Conventionally insulations materials used in a domestic dwellinghouse would include synthetic mineral wool fibres such as glasswool, fibreglass and rockwool. The manufacturing process for glasswool, or fibreglass, involves to expenditure of a large amount of energy to melt down a mixture of dolomite (fine lime), quartz sand, soda and glass. This is then stretched into thin fibres, by the further application of heat. The result is then formed into the desired shape and held a product such as phenol glue. The manufacturing process for rockwool is similar, but instead uses limestone, diabase and coke as the principal raw materials. Nevertheless synthetic mineral wool fibres offer very good thermal insulation, and relatively cheaply. Consequently they are used extensively in domestic dwellinghouse construction. (Berge, 2000).

However a drawback of both glasswool and rockwool when used in conjunction with a timber frame is that because of an inability to deal with moisture, and to prevent dust, a vapour barrier is generally used. This vapour barrier is usually an aluminium foil or plastic sheet. This prevents the wall from being breathable. When a plastic vapour barrier is used, it is generally polyethylene, which uses a relatively high degree of energy in production and has environmental issues associated with its disposal. (Berge, 2000)

In addition rockwool has been shown to increase the extent of rot and damage to the timber frame (Paajanen, 1994). Moreover mineral wool has also been linked to skin and eye problems, itching and also respiratory problems including bronchitis (Berge, 2000). Research has also indicated that damp mineral wool can emit gases such as aliphates, aromates and ketones, when it becomes warm due to heat from the sun (Gustafsson, 1990). These gases can cause irritation to the eyes, nose and throat.

As a consequence we try to promote the use of Warmcel insulation which notes not require a separate vapour barrier, and can be incorporated into a breathable wall.