Installation instructions for rubber tiles over bitumen?

Installation of rubber tiles over roof waterproofing can include levelling small local irregularities using closely fitted pieces of roofing felt.

After rainfall, areas of standing water can be identified. The depressions are filled with one or more pieces of roofing felt laid loosely on top of one another.

A long straightedge or straight metal rail can be used to check whether the depressions have been filled sufficiently. The surface does not need to be completely level. The important points are that as little water as possible remains, the existing fall is retained and the rubber tiles remain stable.

Bonding is not required where the pieces of roofing felt are fully covered by rubber tiles. The rubber tiles laid over them keep the pieces in position.

This method is suitable only for isolated depressions. Inadequate falls, larger deformations and damage to the waterproofing must be rectified professionally.