The rolls are installed in the direction of the water drainage and in a staggered (half-bond) pattern.
The membrane is mechanically fastened to the substrate using appropriate screws and pressure distribution plates designed for the mechanical fastening of bituminous membranes to the existing roof structure.
The membrane is applied with 12 cm longitudinal overlaps and 15 cm end overlaps. All detailing must be carried out in accordance with Buildwise Technical Guideline No. 280 (formerly WTCB).
The number of fasteners in the field, corner, and edge zones is determined by the wind load on the roof (see Buildwise Technical Guideline No. 239).
In case of a single-layer waterproofing system, the seam connections must be carefully executed and thoroughly inspected.
Gutter areas and all details, such as edge terminations, expansion joints, outlets, rooflight upstands, etc., must always be executed in two layers.
In addition, upstands must be provided with a two-layer waterproofing system using vertical strips 1 meter wide. The waterproofing at the upstand must be staggered relative to the field membrane. The underlayer must be fixed using a method appropriate for the existing substrate, ensuring sufficient wind resistance in accordance with Buildwise Technical Guideline No. 280.
More information can be found in our guide:
“How to choose and install the bituminous cap sheet for a flat roof”, available via our IKO website.