Our stucco and frame house was built in the mid-1940s by a contractor for his family. It has Dutch gutters. Since that time a leak on the north side has apparently plagued every owner.
The previous owners replaced the low-pitched part of the roof with shingles. The leaks are near two parts of the roof where valleys are formed.
We, like the other owners, are unable to locate the leak source. We have patched the gutters and replaced downspout tops with wider ones.
Four roofers have visited with no agreement on a solution to the problem. However, all of them do say that the roof is pitched too low to have shingles. The part of the roof that was replaced by the previous owner seems to be OK. One roofer suggests lining the gutters with copper troughs.
If this were your home, what would you do? Our contractor suggests cutting a hole in the stained bathroom ceiling to peer up to see if we can locate the source of the leak from below – while it rains. We don’t have a clue as to how to proceed!
Your suspicion about the valleys is correct. They are prime candidates as leak points.
After removing the wallboard, flood the gutters. If the leak doesn’t show up after about 15 minutes then flood the valleys. If the leak doesn’t show up then, the rest of the roof will have to be flooded a little at a time until the leak shows itself.
In order to install composition shingles, a roof must be pitched so that there is at least three inches of rise for each foot of horizontal travel. With wood shakes the roof must rise at least four inches for each foot of horizontal travel. Otherwise, the roof might leak.
If the roof-pitch is lower than allowed, and shingles are desired, a hot-mopped roof must be installed before the shingles can be applied.