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Under One Roof

Canadian Roofing Reference Manual

6.1 Primer

The roof deck is to be primed prior to application of the hot rubberized membrane. This primer ensures good adhesion between the rubberized membrane and the roof deck.

Prior to application of the primer, the roof deck should be clean, dry and free of all ice, snow, frost or standing water as well as dirt, dust or grease that may cause poor adhesion between the deck and the membrane. The deck should be swept or cleaned by blown air just prior to the primer application and all loose nails, bolts and other debris removed.

Primer is installed either by using brushes, rollers or spray equipment and applied at a rate of approximately 4 to 6 m²/l (160 to 240 ft²/gal). The application rate may vary depending on the porosity of the roof deck. The primer should be applied uniformly avoiding excessive amounts which may pool and pond.

The primer should completely cure before application of the rubberized membrane. The primer could be touch dry in one hour and firm dry in 8 to 12 hours, depending on weather conditions. Some primers may be applied at low temperatures but all applications should take into consideration manufacturers recommendations.

Apply only the amount of primer that can cure and be covered by the rubberized membrane to avoid contamination from dust and dirt that can affect the adhesion of the membrane.