How do you waterproof a flat roof?

Effective flat roof waterproofing depends on creating a seamless, permanently elastic membrane that remains resistant to standing water. Unlike a pitched roof, rainwater cannot drain away freely from a flat roof. It collects in low spots and around roof junctions, where leaks usually develop first.

ALLESDICHT is applied by brush, roller or, on large roof areas, by airless spray in at least three coats onto a clean, dry and sound substrate, whether concrete, bitumen, metal sheet or plastic. Once cured, it forms a seamless, crack-bridging rubber membrane that accommodates movement in the substrate and remains watertight even under standing water.

Particular attention should be paid to roof drains, rooflights, roof edge details, and pipe and cable penetrations. At these highly stressed points, ALLESDICHT is reinforced with reinforcing scrim. For repairing isolated damaged areas on an existing flat roof, a local repair with ALLESDICHT is often sufficient, making a complete replacement of the roof waterproofing membrane unnecessary.