1-The surface to be covered must be so stable not to displace due to exertion of the probable weight pressures. Roofs must be covered with light concrete and finished with sand and cement mortar of at least 2 cm in thickness.  Already asphalted surfaces do not need sand and cement mortar.
2- The surface to be covered with WPBS must be smooth, clean and dry
3-To increase the adhesion of the WPBS, the surface must be given a layer of primer and fast-drying pitch derivatives.
 4-All surfaces must have a slope towards the drain pipe to prevent concentration of water in one area. The maximum recommended slope is 5%
5-Rolls of the WPBS must not be opened in adverse climate like rain, snow, and hail. Each roll of the WPBS must have an overlap of 7-10 cm and an off lap of 15 cm.  Gas torch is used for affixing the rolls along their length and overlapping/off lapping parts are spliced with care so that a smooth surface is formed there.