Flash Harry Bitumen Mastic is a heavy-duty, solvent-based waterproofing repair compound designed for sealing and repairing a wide range of roofing defects. This thick, plasticised bitumen sealer is reinforced with built-in fibres, allowing it to create a durable waterproof barrier without the need for an additional membrane in most applications.
 
Ideal for roofing repairs and maintenance, Bitumen Mastic delivers excellent adhesion and weather resistance on roof screw bolts, sheeting laps, gutters, valleys, cracked tiles, and other vulnerable roofing details. Its solvent-based formulation also allows for emergency repair work, even when rain is imminent.