A.W. STUPART BRE Scottish Laboratory
Since the early 1980s there has been mounting concern at the number of reported cases of rain penetration, particularly of insulated cavity walls. Waterproofing and water repellent surface treatments are being considered to counter such problems. Test methods for the performance of water repellent treatments are given in BS6477. These do not, however, take into account either the crucial influence of mortar joints or the effect of wind-driven rain. BRE has designed a water spray test which takes both these factors into account and results from tests on a range of waterproofing and water repellent treatments on clay and calcium silicate brickwork are presented. Comparisons are made with results using BS6477 methods. The silicone based treatments were the most effective form of treatment with no leakage through the treated masonry and the moisture content of the walling remaining low. Pofyoxoaluminium stearate treatments were moderately effective but a treatment based on acrylic polymers gave poor test results on brickwork. The effects of accelerated weathering on treatments are reported, together with results from spray tests on silicone treated cracked rendered panels. Tests for long term durability, accumulation of salts behind treatments and the influence of crack width are discussed.