Why is my new roof leaking?
Short answer. A new roof that leaks usually has an installation problem at a detail, such as flashing reused or missed at a wall, chimney or skylight, a pipe boot not woven in correctly, nails placed in the wrong spot, or a poorly cut valley. Sometimes it is not the roof at all but condensation or a stain left from before; either way, call the installer right away, because this is what the workmanship warranty is for.
Most common causes
- Reused or caulked flashing: old step flashing or chimney flashing left in place and sealed to new shingles.
- Skylights: a leaking skylight after a new roof often means its flashing was not replaced, or the unit's seal was disturbed during the work.
- Pipe boots and vents: set on top of the shingles instead of woven in, or missing a sealed nail.
- Nailing: exposed nails, nails too close to the center of a valley, or nails driven into a gap between decking panels.
- Valleys: closed-cut valleys trimmed poorly, letting water run under the cut edge.
- Missing kickouts at roof to wall corners.
Not always the roof
- Condensation, especially if ventilation changed and exhaust now outweighs intake.
- Old stains that were never primed and painted, now showing in humid weather.
- Leaks from siding, windows or gutters.
What to do
- Photograph the leak and note the date and weather.
- Call the installer promptly; most workmanship warranties require notice and a chance to fix it.
- Do not let another contractor alter the work first, which can void that coverage.
- Ask for photos of what they find and what they fix.
See roofing warranties explained and skylights and roof replacement.