Roof waterproofing When the roof is the problem

The most common entry points are hairline cracks in the concrete, the joints where the roof meets the parapet, and around the base of drains, pipes and air-conditioner stands. The smooth middle of the roof is less exposed than these edges and joints, so they deserve special care during waterproofing.

Waterproofing stops water getting in through cracks and joints. Heat insulation reduces how much heat passes down into the rooms below the roof. A roof may need one or both, and waterproofing is often treated first because damp under a heat-insulating layer weakens it. We inspect the roof to decide what it actually needs.

Three main systems: bitumen rolls, which are rubber-like membranes laid in overlapping strips and sealed at edges and joints; epoxy, a resin coating that hardens into a water-resistant layer; and polyurethane foam, sprayed on and expanding to cover the surface including small details. Choosing between them depends on the roof's condition and the nature of the problem.

They are two separate problems but can sometimes be treated together. Some waterproofing materials add a modest amount of heat insulation, but a roof that suffers serious heat often needs a dedicated heat-insulating layer alongside the waterproofing. We inspect the roof and decide what is enough and what needs adding.

Water travels sideways through the concrete before it drops, so the stain appears away from where it entered. Searching only at the ceiling does not reveal the source. The right inspection starts at the roof and at the known weak points such as joints and drains, not at the ceiling stain.

Tell us where the damp appears inside or what you see on the roof: cracks, blisters or an old layer. If the problem is heat, tell us which floor you live on and whether you notice a difference between rooms. The clearer your description, the easier it is to decide what the roof needs.