And damaged flashing is behind most roof leaks.
Repairing leaking roof gully.
If a leak is difficult to find enlist a helper and go up on the roof with a garden hose.
In either situation the leaking roof valley can be fixed by removing affected shingles and structural elements and upgrading your roof s flashing.
You could do a diy job with a special waterproof paint can t remember it s name but you can get it in most builders merchants it s a paint with glassfibre in it and when it goes off it dries like a fibreglass shell or you could get a local flat roof firm to felt it with a 3 layer polyester based felt if done right it should last for donkeys years.
For example soak the downhill side of a chimney first then each side then the top on both sides.
Isolate areas when you run the hose.
Press the shingle down then use a trowel to cover the shingle s edges with roof cement.
Removal of debris collecting in the valleys and gutters will allow water to quickly drain away and protect shingles and flashing.
Start low soaking the area just above where the leak appears in the house.
Sometimes an older home s roof is more prone to leaking in the roof valleys because of old repairs.
A flashing is a transitional roofing material that connects the roof material to some other building material or to another part of the roof.
Once the roof valley has begun to leak you will need to cover the valley with flashing in order to prevent a repeat of the problem.
In order to lay the flashing the shingles on the roof will have to be removed.
Straighten and reattach curled shingles.