In his paper the Professor of Building Science at the University of Newcastle-upon-Tyne, UK, argues that the high air humidities and rapidly changing temperatures during winters in Britain create special problems for timber frame construction in that country; the problems are aggravated by the particular methods used in the UK. To counter the risks of interstitial condensation, either the materials from inside to outside of the wall construction should have increasing porosity to moisture vapour, or a ventilated cavity should be provided between the outer plywood sheathing and the timber studs.