joint

Describes different methods for sealing joints. Gives method for testing permeability of joints to wind and rain. Concludes that two-stage joint seems to offer the greatest advantages which are long life, lack of need for maintenance, lack of sensitivity to tolerances, extensive lack of sensitivity to faulty installation practice and installation independent of the weather. Tests confirm that the wind permeability of two-stage joints can be practically disregarded in the determination of heat requirements.

A number of cases of water and frost damage in masonry and non loadbearing walls have been examined. This damage could not have resulted from vapour diffusion or rain penetration and is primarily caused by condensation due to exfiltration of air. Air exfiltrates through the many cracks and joints and in this connection the result of chimney action and wind is explained in some detail, including the pattern and magnitude of building pressure differences that induce ex-filtration together with a discussion regarding the moisture that is transferred.