The following repair is utilised in several different repair situations which require installing a patch to return the membrane to a watertight condition. To promote thorough adhesion ot‘a patch, it is essential to begin by preparing the surface. Remove debris, contaminants, aggregate or loose surfacing from the surface of the membrane or flashing to be repaired. The area to be prepared should extend a minimum of 18″ (450 mm) beyond the perimeter of the defect to provide a clean work area on which to install the patch and tie it into the existing roof membrane.
On gravel surfaced roofs, carefully spud the aggregate free from the surface and sweep clean.
Prime the surface of the membrane with asphalt primer and allow to dry.
Where plies are removed from the membrane, install the same number of plies (a minimum of 2 plies) in hot bitumen or cold-applied adhesive. Extend the bottom ply at least 6″ (150 mm) beyond the area to be repaired and each succeeding ply at least 3” (75 mm) beyond the previous ply. When using hot bitumen as the method of application, take care to maintain the bitumen at its proper EVT. As an alternative, on asphalt BUR membranes only, modified bitumen membrane sheets may be installed by torch application, in hot asphalt or suitable cold adhesive. When using hot asphalt as the method of application, use Type 3 asphalt and take care to maintain the asphalt at 400°F
To reapply the surfacing, embed gravel in hot asphalt or roof cement or apply a surface coating compatible with the existing surfacing. Liquid applied coatings should be installed in accordance with the coating manufacturer’s instructions, which may include a waiting period.