Where is a roof most likely to leak?

Residential roof leaks are most likely to occur at architectural roof penetrations, junctions, and areas where water accumulates or changes direction. Key leak hotspots include roof valleys where two slopes meet; around chimneys, skylights, and plumbing vent pipe flashings where metal meets shingles; along roof pitch transitions; and near clogged gutters or blocked eaves where water backs up under the shingle overhangs. Additionally, worn or missing shingles on south-facing roof exposures are vulnerable. You can troubleshoot attic leaks safely by using a flashlight to inspect rafters from below during rain. You can verify that your corrective action is successful when inspecting these key exterior zones and applying proper flashing sealant or replacing damaged shingles eliminates water stains in your attic.