ABSTRACT
The acceptable modern methods of insulation, whilst efficient in controlling internal temperatures, vary in their impact on the ability of the structure to deal with trapped moisture, and on the health of the occupants. High moisture levels can diminish thermal performance insomuch as the more a pore structure is in filled with moisture, the less able it is to hold air, which reduces the ability of the structure to trap warmth within it. Cavity wall construction has readily embraced further insulation being provided by adhering insulation boards to the outside face of the inner leaf of the cavity. Three materials are commonly used for cavity wall insulation: expanded polystyrene in bead form; chopped mineral wool; and the even more worrying urea formaldehyde foam. Traditional timber framing gave no credence to insulation save through the unique quality of the clay daub wrapped around the oak staves and hazel wattle basket weave.
