Various kits containing special tape and adhesive are available for carrying out patch repairs. These should obviously be carried out in dry weather.
Clean the area thoroughly removing chippings and killing off any mould growth with fungicide.
If the surface is split, fill the gap with bitumen compound before patching.
If you have a burst blister, dry it out first with a hot air stripper. In the case of asphalt, you may be able to fill in the hole by spreading the warm asphalt with a stripping knife.
Allow to cool, then prime the surface of the area to be repaired with the special primer supplied.
Cut the tape to length and press firmly down into place.
Make sure the edges are well sealed.
When complete, recover with chippings as before or ‘blind’ with sand to protect the surface.
Felt covered roofs
In the case of felt, carefully make a cross cut in the surface and lift up the flaps to dry it out. Apply bitumen adhesive to the hole before folding back the flaps and pressing down into the adhesive.
This area should then be further protected by coating with the bitumen adhesive and patching with a square of roofing felt a little larger than the damaged area. Once again, make sure this is firmly pressed down and well sealed at the edges.
Whole surface treatment
If you have several repairs looking somewhat unsightly and there are signs that further deterioration is imminent, it may be rejuvenated by treating the whole surface
Brush off all loose material and treat the surface with fungicide to kill off any mould growth.
Once cleaned and allowed to dry, apply liquid bitumen – purpose designed for the job. . Plan your work pattern to avoid being 'boxed' in by the wet bitumen. Use an old broom to spread this as it will be a thankless task to try cleaning it out afterwards.
To provide additional strength, lay glass fibre matting. This is pushed down into the bitumen before it dries and should be tamped down so that it is thoroughly coated. To ensure continuity of strength, overlap the glass fibre joins by a couple of inches.
Allow to dry according to the manufacturer’s instructions before applying a second coat of the liquid bitumen. When this is dry, apply a third and final coat but ‘blind’ this with sharp sand before it has fully dried. Spread the sand lightly using a seed sowing action.