A roof leak is a nuisance and also an emergency, therefore finding its cause as well as its location is imperative. However, roof leaks can be difficult to diagnose, especially if they went undetected for a while and water traveled from the entry point and infiltrated far from it.
There are some common leak location though that you should maybe start with, when you are not sure where to look.
Damaged shingles represent the most obvious cause for roof leaks, so they have to be inspected carefully. Do not look only for missing, cracked or curled shingles, but also for rather subtle signs of damage, such as missing granules. If the roof is old and shingles are work out, this is likely another reason for the appearance of water leaks. Quality San Jose roofing contractors can easily spot and repair a roof leak.
Roof valleys are those lines where roof planes intersect. They are secured with flashing, but they still represent vulnerable areas of a roof. When flashing become worn out, water can easily find its way inside.
Flashing is also used around other roof penetrations such as dormers, skylights or chimneys. These areas are also very likely to allow water leaks, if the materials do not provide adequate protection anymore.