Exposed roofing nails.
Exposed roofing nails are sometimes a source of leaks.
Cover exposed nail heads with a dab of
roofing cement, when exposed nails can't be avoided
— as on cap shingles.
Excessive shingle overhang.
This installer apparently believed that increasing the overhang
on the first course of shingles would help direct the water
into the gutter, and would substitute for metal drip edge.
Eventually, however, the shingles crease under their own weight
and break off, exposing the edge of the sheathing beneath.
Shingles should overhang 1/2 inch to
3/4 inch beyond the metal drip, according to
recommendations from the Asphalt Roof Manufacturers
Slipping shingles. Shingles
can slip when the manufacturer's fastening instructions are not
followed. Improper practices include using too few fasteners,
and overdriving and underdriving the fasteners.
Follow the shingle manufacturer's
fastening instructions as printed on the bundle
Problem: The owner calls to report a roof
Solution: Not every leaky roof is the fault
of the contractor.