How do you find the source of a roof leak?
Leak detection is mostly careful looking. A crew usually starts inside, checking the attic for damp insulation, dark stains on the rafters and daylight where it should not be. Then they work outward and uphill from the stain, because water travels along the underlayment and framing before it drips.
On the roof, the usual checks are:
- Flashing at every wall, chimney and penetration
- Nail pops and exposed fasteners
- Cracked, curled or missing shingles
- Sealant that has dried out and split
Sometimes the cause is not obvious, and a controlled water test with a hose, one section at a time, helps confirm it. Be wary of anyone who names a cause without going into the attic or onto the roof. A quick coat of sealant over the stain rarely fixes anything for long.
