Florida Certified Roofing Contractor CCC 1334537
Why is water still sitting on my flat roof days after it rains?
A straight answer from a Florida certified roofing contractor — then what you can check yourself and when to call. Free quote: (954) 775-8990.
Water still sitting on a flat roof long after the rain has stopped means the roof is not draining — either the surface has lost the slight slope it was built with, or the drains, scuppers and gutters that should carry the water off are blocked or set too high. Roofers call this ponding, and it is a defect rather than a normal feature of a low-slope roof.
Flat roofs are never truly flat. They are built with a slight pitch toward drains or edges, and when a deck sags, insulation compresses, or a drain sits above the surrounding surface, water collects in that low spot and stays until it evaporates. In Florida's humidity, evaporation is slow, so a pond can persist for days.
Why it happens
The most frequent causes are structural and gradual. Decking or framing deflects over time between supports, insulation under the membrane gets wet and compacts, or a previous repair added material in one place and created a dam. Once a low spot forms, standing water adds weight, the deck deflects a little more, and the pond grows.
Drainage is the other half. Roof drains clog with leaves, gravel and sediment; scuppers through a parapet get painted over or blocked; and on additions, a drain may have been installed slightly high relative to the finished surface. Rain ends, but the water has nowhere to go.
Ponding matters because it works on the weakest parts of the assembly. Constant moisture degrades membrane and seams, UV plus heat on a wet surface accelerates aging, debris and algae collect in the pond, and dissolved water finds its way through a pinhole or a lap that has lifted. A pond directly over a seam or a base flashing at a curb or parapet is more concerning than one in the open field.
What you can check yourself
Look from a window or balcony
From an upstairs window, a balcony or a neighbouring vantage point, note where the water sits and whether it is near a drain, a wall or the middle of the roof. Stay off the roof — a wet low-slope membrane is slick and the deck under a pond may be soft.
Watch the ground during rain
During a downpour, see whether water actually discharges from the downspouts and scuppers. Little or no flow while water builds on the roof points to a blockage rather than a slope problem.
Check the ceiling below
Look for stains, bubbling paint, sagging drywall or a musty smell in the rooms directly under the ponded area. Stains that darken after rain suggest water is already getting through.
Check the attic or ceiling cavity
If the low-slope section has accessible framing above the ceiling, look for damp sheathing, rusty fasteners or daylight. Use a flashlight and stay on secure framing.
Note the pattern over time
If the same spot holds water after every rain and the ring of dirt is growing, the deflection is progressing. That is useful information for whoever inspects it.
When to call a pro
Call a roofer if the water sits for days every time it rains, if a ceiling below is stained, if the membrane in the pond looks blistered, wrinkled or has open seams, or if the roof feels spongy where anyone has walked. Clearing a drain may stop one pond, but a low spot caused by a sagging deck or wet insulation needs the assembly opened up and corrected.
Low-slope roofing is roofing work in Florida and generally requires a DBPR-licensed roofing contractor, with a permit from your city or county building department for reroofs, recovers and most repairs — condo and HOA owners usually need association approval too. Verify any contractor on DBPR's license search; Flat Rate Roofing Inc holds Florida Certified Roofing Contractor CCC1334537, valid in every county, and we pull permits under our own license and close them out. We are insured, our phone is answered around the clock, and estimates are free.
What a pro will do
- Find the low point and the causeWe map where water stands, check drain and scupper heights against the surface, and probe for soft deck or saturated insulation.
- Correct the slopeTapered insulation and crickets are used to rebuild positive drainage toward drains and scuppers so water leaves instead of collecting.
- Add or rework drainageNew drains or scuppers can be set at the correct level, and existing ones cleared and reflashed into the membrane.
- Replace the failed membrane and deckDepending on the system, we install hot mop built-up, modified bitumen or torch-applied cap sheet, or a self-adhered system, replacing rotten plywood and fascia as part of the scope.
- Reflash walls, curbs and parapetsBase flashing at parapets and curbs is rebuilt so the vulnerable upturns are sound, and attachment is detailed to meet the code requirements that apply.
Related questions
- Does ponding water always mean I need a new roof?
- No. Sometimes the fix is clearing drains, adding a scupper or rebuilding one low area with tapered insulation. Full replacement comes into it when the membrane is at the end of its life, the deck is rotten, or too many layers already exist for a recover.
- What will the repair cost?
- It depends on the size of the roof and the ponded area, the system you have, roof access, how much tapered insulation or drainage work is needed, permit requirements and what is found once the roof is opened up. We give a free estimate and a written flat rate quote that says what is included — call (954) 775-8990.
- Can I just patch the low spot myself?
- Surface patches over a pond rarely hold, because the patch edges sit in standing water and lift. Correcting drainage is what actually stops the problem, and low-slope roofing work in Florida generally requires a licensed roofing contractor and a permit.
- Do wind and code rules affect a flat roof repair?
- Yes. Florida Building Code requirements for low-slope attachment and drainage apply statewide, and products need Florida Product Approval; in the High-Velocity Hurricane Zone — Miami-Dade and Broward counties only — Miami-Dade NOAs are commonly required for the full assembly. Your building department confirms what applies at your address.
- Is there a limit to how much of my flat roof can be repaired?
- Florida has a rule limiting how much of a roof area may be repaired within a twelve-month period before the section has to be brought up to current code. How it is applied varies, so check with your local building department before scoping a large repair.
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