Small cracks or splits with no bubbling of roof surface If you find small cracks or splits and the surface still appears flat, then the surface can be easily repaired using bitumen mastic spread evenly over the area. Self-adhesive repair tapes are also available for this type of repair. However make sure that the surface is thoroughly clear of debris and cleaned carefully before application. This is because the effectiveness of the repair is only as good as the seal between the spread and the surface. Choose a dry, warm day to repair the surface. Once the bitumen mastic is smoothly in position, apply more compound to the surface to seal completely and cover with some gravel chipping to match the rest of the surface. The chipping compound, such as limestone, gravel or granite on top of the layers of felt, strengthens the surface further. The idea is for the surface to reflect rather than absorb sunlight, thus helping to protect the felt.
Cracks and signs of bubbling If the cracks are also showing signs of bubbling, then water could possibly seep through the surface. Moisture has already penetrated under the felt. When the roof has warmed in the sun the felt swells in the heat causing blistering on the surface. Choose a dry, warm day to make a cross shaped cut in the centre of each bubble and open up to allow the area to dry out completely. Allow some drying time, before using a cold bitumastic compound to bed the felt back into position. If necessary, the area can also be nailed back into position with galvanised clout nails. Once the felt is back in position, apply more compound to the surface to seal completely and cover with some gravel chipping to match the rest of the surface. The chipping compound, such as limestone, gravel or granite on top of the layers of felt, strengthens the surface further. The idea is for the surface to reflect rather than absorb sunlight, thus helping to protect the felt.
No cracking, no bubbling, but signs of dampness If there is no evidence of cracking or bubbling, yet there are signs of dampness on the ceiling below, check the flashing. The flashing strip should be set against the wall and be totally watertight. This area can sometimes come away from the wall allowing water to trickle below the surface of felt. Choose a dry, warm day to repair the roof. Take the flashing strip off by prising it away from the wall. Clean the area by raking out old debris and mortar. Use a ready mixed mortar if only a small amount is required. Brush away any dust or grit and dampen the joists with an old paintbrush. This will stop the mortar drying too quickly and cracking. Use the mortar to fix the flashing strip into position and re-point the joist.
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