Take care to provide a suitable, safe means of access to any roof. Remember also, to take care when working near the edges of the roof. If you have any doubts about a safe means of access, consult a professional. Make sure that the roof structure itself is sound and capable of supporting your weight
Examine the overall condition of the flat roof covering. If it has deteriorated significantly over a large part of the total, consider getting a quote for its replacement. Whilst repairs on a serviceable covering are sensible, as it gets towards the end of its useful life, repairing may be uneconomic.
Finding the leak
The first problem can often be locating the source of the fault. You may well be able to see where water is seeping through into the ceiling below, but the point at which the water is getting in may not be immediately above.
Where dampness appears at the ceiling edges, the usual cause is a defective flashing – the sealing strip at the edges.
To find the source, identify the corresponding position on the roof above the damp area. Flat roofs have a slight slope, so the source must either be here or uphill from this point. Examine the surface for cracks, splits or blisters.
If the roof is covered with chippings, sweep these away to enable closer examination. Where the chippings are stuck in the bitumen, apply light heat with a hot air stripper to soften the bitumen and release the chips.
If there are splits, these may be caused by movement in the roof structure, usually as a result of expansion and contraction under the heat of the sun.
Blisters may be caused by moisture penetration, or trapped air. They can be squeezed lightly to see if they have any weakness. If they are sound, they are probably best left alone rather than creating more problems.