Subroof membranes
Second water-draining level below the roofing to provide additional protection against the elements They are waterproof across their surface, including the seam and join area. A distinction is made between waterproof and rain-proof subroofs. Subroof membranes are installed as additional protection under roof claddings consisting of clay or concrete roof tiles. They are laid on timber boarding, composite boards or pressure-resistant thermal insulation layers. With a watertight subroof, the counter batten is incorporated in the waterproofing (cap flashing), whereas with the rain-proof subroof, the counter batten is underlaid with a nail-sealing strip.Worth knowing ...
What is the reference roof pitch?Reference roof pitch refers to the shallowest roof pitch at which a particular roofing material proved in practice to be sufficiently rain-resistant. The reference roof pitch for a roofing material is generally specified by the manufacturer.
For the decision on whether a subroof membrane, underlay or sarking membrane needs to be used, technical guidelines dictate that it is not only a question of whether or not the roof pitch is less than the reference pitch; there are additional issues to take into account regarding increased requirements such as roof pitch, structure, usage, climatic conditions and local regulations, all of which influence the roof. Thus, additional protection for the roof - subroof membrane, underlay or sarking membrane - is determined on the basis of the individual project.