If water sits on your flat roof for days after it rains, that’s ponding, and it’s one of the main reasons flat roofs fail early.
Why ponding is a problem
Standing water breaks down roofing membranes, adds weight, and finds every weak seam. It also grows algae and collects debris that clogs drains.
Common causes
- Roof deck sagging over time
- Drains or scuppers set too high or clogged
- No crickets to steer water around obstacles
- Previous patches that created low spots
How it’s fixed
- Clearing and resetting drains and scuppers
- Adding tapered insulation or crickets to create slope
- Re-roofing with a membrane suited to the roof, such as torch-down
- Applying a coating to a sound roof after drainage is corrected
A simple test
After the next rain, check the roof (or have a roofer check it) 48 hours later. If water is still standing, it’s time to address the drainage.
A recent example
On one recent job, water kept pooling in the middle of a flat section and causing leaks. We re-sloped the area so water runs to the drain, then installed the new roofing on top. Fixing the slope first is what keeps the new roof from failing the same way the old one did.
Questions about your roof? Call Crown Roofing and Repairs at (818) 350-2740 for a free estimate anywhere in the San Fernando Valley. Licensed C-39, CSLB #C39-1156638.