Research done by Tim Padfield in Denmark, shows that moisture absorbing walls play an important role in the health of large public buildings, as well as in private houses. His comprehensive research is worth a visit at
Organic Builders who use large amounts of organic materials can rely on those materials to
breathe and moderate the moisture variations within the building. "The Healthy House" (1)
points to some concerns with modern building design and materials. Air pollution inside a
modern building can be many times greater than the air outside. Walls which breathe can
exchange and filter the air and greatly reduce internal air pollution. Porous hygroscopic
materials such as straw and timber can take in and release moisture and so act as a natural air
conditioner. The diffusion resistance factor (DRF) of a material is a useful indicator of its
capacity to resist the intake and release of water vapour, and diffusion of stale interior air.
Table 5 gives the DRF factors for building materials, the higher the DRF, the less it breathes
and the less acceptable it is for a healthy house.
|Mud & Straw blocks
|Solid Timber treated with natural paints and
||less than 5|
|Wall boards - plywood
- tempered, coated hardboard
|Vapour barriers - aluminium foil
Table 5 (2)
1. 1."The Health House" by Sydney and Joan Baggs - Harper Collins 1996.
2. 2."The Healthy House" page 134