The stain on the ceiling is almost never under the hole in the roof. Water gets in at a seam, a flashing or a drain, then travels along the top of the deck or under the insulation until it finds a joint to drip through. That is why so many flat roof leaks get "fixed" three times. Here is how leaks are found and fixed properly.
What to do right away
- Move inventory, files and electronics away from the drip, and catch the water.
- Shut off power to any light fixture or panel that is getting wet.
- Keep people out from under a ceiling that sags with water above it.
- Don't go on the roof in a storm, in the dark, or when it is icy or snow-covered.
- Take dated photos inside, for your records and your insurer.
Then request service. Active leaks can usually be dried in temporarily until a permanent repair is possible. See emergency roof repair.
Where flat roofs usually leak
Flashings at walls and parapets
Where the roof turns up a wall, the membrane is stretched, fastened and terminated, and that termination ages first. On older brick buildings, the wall itself often lets water in above the flashing. See parapet and flashing repair.
Seams
Glued EPDM seams on older roofs let go with age; welded TPO and PVC seams can have cold welds from the day they were installed. Freeze and thaw works on any weak seam every winter.
Penetrations and rooftop units
Pipe boots crack, pitch pockets empty out, and curb flashings get stepped on during HVAC service.
Drains and scuppers
A drain bowl that has pulled loose from the membrane leaks every time it rains. A drain that freezes in winter backs meltwater up against everything nearby. See ice dams on flat roofs.
Punctures
Dropped tools, foot traffic, hail, and the snow shovel. Spring inspections turn up a lot of shovel cuts.
Roof leaking right now?
Wausau Superior Flat Roofing repairs, coats and replaces commercial and flat roofs across Wausau and central Wisconsin, with a written price before any work starts. Request a quote online and we’ll call you back.
How leaks are traced
We start inside, where the water shows, and map it to the roof above, then look uphill of that spot in the direction water flows on that roof. The likely details get inspected closely: probing seams, checking flashing terminations, looking for cracked sealant and loose drain clamps. When a leak is stubborn, controlled water testing of one detail at a time, moisture readings and a core cut tell us where the water is traveling. See leak detection and moisture surveys.
What a proper repair looks like
- Same-material repairs: EPDM gets primed EPDM tape and patches; TPO and PVC get welded patches; modified bitumen gets compatible ply.
- Clean, prepared surfaces: patches bond to clean membrane, not dirt, old caulk or roof cement.
- Wet material replaced: wet insulation under the leak is cut out and replaced, or it keeps causing trouble.
- Cause fixed: if the drain froze or the wall let water in, that gets fixed too.
- Photos: before and after, so you know what was done.