Leaks & sources
Flat roof leaking after rain: why it happens and what to do
Updated
Short answer
Flat roofs leak when water ponds and finds a weak spot: clogged scuppers, worn coatings, cracked parapet flashing, or penetrations for coolers and AC units. Catch the water inside, get the roof tarped or sealed, and have the ceiling and insulation checked.
Common causes
- Clogged scuppers and canales
- Foam or elastomeric coating worn thin by UV
- Cracks where the roof meets parapet walls
- Seals around cooler ducts, AC stands, vents and skylights
- Low spots that pond water for days
Inside the house
- Catch drips and move belongings.
- Turn off power to light fixtures that are dripping.
- Keep out from under sagging drywall.
- Photograph ceilings and walls.
Prevention
- Have the roof inspected before monsoon season.
- Recoat foam and elastomeric roofs as recommended.
- Clear scuppers, canales and roof drains after dust storms.
- Check penetrations for coolers and AC units.
Questions
How long does a foam roof last?
With regular recoating, foam roofs can last many years; without recoating, UV breaks down the surface.
Is a flat roof leak covered by insurance?
Sudden storm damage may be covered; leaks from worn coatings and lack of maintenance usually aren't.
Can wet insulation stay?
Soaked blown-in insulation usually needs replacement to prevent mold and restore its insulating value.
Editorial note: this guide is general information for Arizona homeowners, not professional, legal or insurance advice. For your situation, talk to a licensed contractor and your insurer.