Abstract
Attention is paid to the problems of the protective waterproof membranes of sloping roofs. The article presents a laboratory analysis of protective waterproof membranes according to their deree of watertightness. The laboratory analysis consists of 3 kinds of laboratory measurements: watertightness by a method of constant loading by a water column, watertightness by the method of a maximal water column up to 1500 mm, and watertightness by a dynamic method through rain simulation.