Flash Harry Bitumen Mastic Trowelable Waterproofing Sealer 5 Litre

Flash Harry Bitumen Mastic Trowelable Waterproofing Sealer 5 Litre is a heavy-duty, trowel-applied compound for sealing roofing defects and repairs. With a built-in membrane, this bulk 5 litre size suits larger roofing jobs and extensive waterproofing across multiple defects and long runs.

Clean the area of dust and loose material, then trowel the mastic firmly over the defect, working it into the joint. In UV-exposed areas, overcoat with Alu-Coat Silver for added protection, and clean tools with thinners or solvent. Take fire precautions, as it is flammable when wet.

A dependable, membrane-backed seal sized for bigger roofing jobs.

Flash Harry offers practical building and waterproofing products aimed at fast, effective repairs for contractors and homeowners alike, formulated for real-world roofing and sealing jobs.