Commercial flat roof repair: patch, coat or tear off, decided from the survey
State Restoration Services repairs TPO, EPDM and modified bitumen roofs on stores, offices, industrial buildings and apartment blocks across the north and northwest Chicago suburbs. Most leaks on these roofs start at one detail, and the job is to find it, fix it and tell you honestly what the rest of the roof needs.
The systems we install and how long each lasts are compared on our commercial roofing page. This page is about the roof you already have.
1A lifted seam where two sheets of membrane meet. Water runs under the sheet from here.
2Cracked flashing at the corner of a rooftop unit curb, the most common leak point on these roofs.
3A soft patch underfoot: the insulation board under the membrane has taken on water.
Patch, coat or tear off: the insulation under the membrane decides
A flat roof has three layers that matter: the membrane on top, the insulation board under it, and the deck. A leak at a seam or a curb usually leaves most of the board dry. Once water has spread through the board, a patch on top cannot dry it out, and the wet board keeps feeding the ceiling below.
Repair the detail
The membrane is sound and the water got in at one place: a seam, a curb, the top of a parapet, a drain. We open that detail, cut out any wet board around it and rebuild it.
Most leak calls end here.
Restore with a coating
The membrane is aging across the whole roof but still attached and whole, and the board is dry. After the details are repaired, a restoration coating over the cleaned roof can add years for a fraction of a new roof.
A white coat also reflects summer sun, the idea behind a cool roof.
Tear off and replace
The insulation is wet across large areas, or the membrane is past its service life. This is the only case where we recommend a tear-off.
The new roof is chosen from the systems on our commercial page.
When the building code rules out a roof over a roof
The reroofing section of the International Building Code requires the old roof to come off when it is water-soaked or so deteriorated that it is not a sound base, and when it already has two or more layers. Some local codes add a number: a full replacement once more than 25 percent of the roof area holds moisture. Building Enclosure lays the rules out in Roofing Code: Recovering Versus Replacement.
Moisture under a membrane is found with an infrared scan, a nuclear or capacitance meter, or a small test cut. The edition your village has adopted is the one that applies to your building.
The repairs we make most, and what you should see afterwards
Every repair below ends with the detail rebuilt, not smeared over. Sealant alone on a flat roof is a temporary stop, and we label it that way in the report when we use it.
| What failed | The repair | What you see afterwards |
|---|---|---|
| An open or lifted seam on a TPO roof | The lap is cleaned back to bare membrane and heat-welded again. A run with damaged edges gets a new strip welded over it. | A welded lap that does not open when it is probed |
| An open seam on an EPDM roof | The lap is cleaned and primed, then sealed with seam tape or a cover strip over the old joint. | A strip a few inches wide running along the old seam |
| Cracked flashing at a rooftop unit curb | The old wrap comes off and new membrane flashing runs up every side of the curb, with its top edge under the curb's metal. | Flashing on all four sides of the curb, not a ring of caulk |
| A split at the top of a parapet wall | The coping metal comes off, the membrane is turned up and fastened at the top, and the coping goes back with its joints covered. | Coping that sits tight with no open joints |
| A blocked drain or scupper | Debris is cleared, the clamping ring that holds the membrane at the drain is checked and the strainer is set back. | No standing water around the drain after rain |
| Water ponding in one low spot | Drainage is cleared first. A low spot that still holds water is marked in the report for extra slope at the next re-cover or replacement. | A marked area on your roof plan with a plan for it |
A repair day that keeps the doors open
Commercial work is scheduled around the building, not the other way round. We agree the timing before the crew arrives.
The call
You tell us where the water shows inside and how we get onto the roof.
The survey
We walk the whole roof and photograph the penetrations, drains and seams, not only the spot above the leak.
The plan
Early starts, weekend phases or one section at a time, so entrances, loading and tenant space stay usable.
The repair
The failed detail is opened, wet board under it is replaced and the detail is rebuilt.
The report
Photos of each repair and of the roof's condition, with anything else we found listed by how soon it needs work.
What to send with the first call
On a flat roof the water often travels along the deck before it drops, so the wet tile inside can be several feet from the opening above. A few details from you let the survey start in the right place.
If water is coming through now, put a container under it and move stock, records and equipment away from the area. Note the time it started and whether it was raining or snow was melting.
The leak call checklist
- Photos of the stain or wet ceiling tile, and where it is: which tenant, which room, near which wall or column
- Whether it leaks in every rain, only in wind-driven rain, or when snow melts
- What sits on the roof above it, such as a rooftop unit, a skylight or a drain
- How we get up: roof hatch, fixed ladder or a locked access, and who holds the key
- The roof's age and surface if you know them: white TPO, black EPDM rubber or a granular modified bitumen
- Earlier repairs on that area, and roughly when they were made
Hail and wind on a commercial roof
Hail can bruise a membrane and crack the insulation board under it without leaving a visible hole. Wind lifts the roof edge and peels perimeter flashing and coping. Both can show up as leaks weeks after the storm.
We document the damage with photos and measurements the same way we do for homes, and write a code-compliant estimate for the carrier.
Illinois law does not let a roofer negotiate a claim. Our partner, the licensed Illinois public adjuster State Adjusting Services, can represent the property owner on the claim itself, and the insurer decides what it pays. Our storm and insurance page explains how the two parts fit together.
For a flat porch roof, a dormer or an addition on a house, see our flat roofing page for homes.
Questions property managers ask about flat roof leaks
Can a leaking flat roof be repaired instead of replaced?
Usually, yes. When the membrane is sound and the water came in at a seam, a curb, a parapet or a drain, rebuilding that detail stops the leak. Replacement is only on the table when the insulation is wet across large areas or the membrane is past its life.
How do you know if the insulation under the membrane is wet?
Wet board shows as soft spots underfoot, blisters and stains that keep spreading. It is confirmed with an infrared scan, a moisture meter or a small test cut, and the amount of wet board decides between a repair, a coating and a tear-off.
Will the repair shut down our business?
No. We agree the timing first: early starts, weekend phases or one section at a time, so entrances, loading docks and tenant space stay in use while the crew works on the roof.
Is a roof coating a repair or a replacement?
Neither. A restoration coating goes over a membrane that is aging but still attached and whole, after its seams and flashings are repaired. It adds years to that roof, and it is never put over wet insulation.
Want this looked at?
We inspect for free, document what we find and prepare a code-compliant estimate you can hand to your insurer. Our partner, a licensed public adjuster, State Adjusting Services, can represent you on the claim.
Call (866) 992-2982. Free Inspection