Commercial flat roof repair
"Flat" commercial roofs are really low-slope roofs, built with a slight fall to drains, and they are covered with one of five membrane families: TPO, EPDM, PVC, modified bitumen or built-up. Repairs typically cost $2 to $10 per sq ft of damaged area, and most single repair visits land between $300 and $1,100.
Repair cost
$2 to $10 per sq ft
Most visits $300 to $1,100.
Defects a flat roof repair fixes
- Ponding water that stays more than a day or two after rain.
- Blisters, ridges and wrinkles where the membrane has lost adhesion.
- Splits and cracks at the field or along the edges.
- Open seams and laps on single ply and modified bitumen.
- Worn or missing surfacing that leaves bitumen exposed to the sun.
- Failed flashings at curbs, walls, drains and penetrations.
Flat roof repair prices
| Job | Typical price |
|---|---|
| Built-up (BUR) Per sq ft of repaired area | $3 to $7 per sq ft |
| Modified bitumen Per sq ft of repaired area | $3 to $8 per sq ft |
| EPDM Per sq ft of repaired area | $5 to $10 per sq ft |
| Patch Small, single area | $150 to $1,500 |
| Reseal Seams and details, every few years | $400 to $1,250 |
| Ponding water Drain work, crickets or tapered infill | $70 to $750 |
Typical US prices from published national roofing cost guides, January 2026 editions, read November 2026. Installed, in US dollars, before any local tax. A guide, not a quote. TPO and PVC repairs are priced by the job in the guides; see their pages.
What a sound flat roof repair includes
A dry, clean, primed surface
Patches and seams only hold on clean, dry membrane. A roofer who patches over standing water or dirt is selling a callback.
The cause, not just the drip
Water travels under membrane and along deck flutes, so the wet ceiling tile is rarely under the hole. A good repair names where the water got in.
Drainage checked
Clear drains and scuppers, check the overflow drains or scuppers the building code calls for, and look at why water ponds before patching where it sits.
Wet insulation found and dealt with
Wet board loses most of its insulating value and holds water against the deck. Cores or a moisture survey show how far it has spread; badly wet areas are cut out and replaced.
Photos before and after
Dated photos of every repair, and its location on a roof plan, protect your warranty and any insurance claim, and help the next roofer.
Safe access and fall protection
Work near an unprotected edge on a low-slope roof calls for fall protection under OSHA 1926.501: guardrails, safety nets, personal fall arrest or the combinations the rule allows. Ask how the crew will get up and stay safe.
Flat roof leaking or ponding? Get a commercial roofer who covers your area to look at it.
Ask for a free quoteHow a flat roof repair usually goes
Find the entry point
The roofer walks the roof, checks the areas above the leak and upslope of it, and may use a moisture meter, infrared scan or cores.
Make it watertight
If water is coming in, a temporary repair first: a compatible patch, sealant or tarp held down so wind cannot lift it.
Permanent repair
The proper detail for the system: a heat-welded patch, taped seam, re-set flashing or a section of new membrane.
Report and photos
Before and after photos, what was found and what to budget for next, so you can decide between repair and replacement with facts.
Questions people ask
What does it cost to repair a commercial flat roof?
Typically $2 to $10 per sq ft of damaged area, or $300 to $1,100 for most single visits. Use the repair cost estimator for your system and roof size.
Is ponding water on a flat roof a problem?
Some water after rain is normal. Water that stands for more than about 48 hours speeds up aging, adds weight and finds every weak seam. Drains, crickets or tapered insulation are the usual fixes.
How long does a commercial flat roof last?
Roughly 15 to 30 years depending on the system, the installation and how well it is maintained. See the roof system pages for each type.
Can you put a new flat roof over the old one?
Sometimes. Under the International Building Code a recover is not allowed over a roof that is water-soaked or deteriorated, or where there are already two or more roof coverings. A moisture survey decides it.
Should a flat roof be coated?
A coating can extend the life of a sound, dry roof and make it reflective. It does not fix wet insulation or structural problems, and should not go over a roof that is failing.
Where our information comes from
Get the flat roof repaired
The building ZIP, where to reach you, then a few taps about the roof. About a minute.
This is a free matching service, not a commercial roofer. We look for one who works in your area and tell you their name before anything is shared. Nobody contacts you until you say yes.
Thanks, your enquiry is in.
- We look for a commercial roofer who covers your building and does this kind of work, then email or call to tell you who it is.
- Your details reach that firm only if you say yes.
- They inspect the roof and give you a written price. No marketing from us, ever.