Is a flat roof supposed to hold water?

No. A low-slope roof is designed to drain. Water still standing long after the rain is ponding, and ponding shortens the membrane. The fix is often drainage and slope, not only a new sheet.

What is the difference between a recover and a tear-off?

A recover puts a new membrane over a dry, attached roof when the deck and the code at that address allow it. A tear-off takes the roof down to the deck, which is the right scope when the insulation is wet or the layers are already too many.

Do you install TPO and EPDM?

Yes. Both are single-ply membranes we install. They are detailed differently. The TPO and EPDM page explains the difference, including fully adhered and mechanically attached installation.

Can you coat a flat roof instead of replacing it?

Sometimes. A coating is a restoration of a dry, attached roof. It is the wrong product when a core cut shows wet insulation or the deck has failed. That choice is on the coating page.

My flat roof leaks. Do I start here?

Start with the repair site if you want the leak found and fixed. Come here when the roof needs to be replaced or you already know the membrane is finished. We will say which one it is after we look.

How long does a flat roof replacement take?

It depends on the size, the weather, the tear-off and whether the building stays open. The sequence is in the scope. We do not promise a number of days on this page.

What should I compare in two flat-roof bids?

Tear-off or recover, insulation and whether it is tapered, drains, flashings, edge metal and what happens if the deck is soft. Two totals are not comparable until those lines match.

Do you list a price for a flat roof?

No. The price is a written scope after we see the roof. This page only lists what usually changes that number.

Do I get photos from the inspection?

Yes. We photograph what we find and go through it with you, so you see what we saw.

Flat Roofing in St. Louis | Flat Roof Replacement · St. Louis Roofing & Exteriors

Flat and low-slope roofs we replace and install

A flat roof is almost never truly flat. It is a low-slope roof that has to move water to a drain, a scupper or off the edge. When that slope is missing, water sits, and sitting water finds every weak seam. The roofs we replace and install in this category are the low-slope sections on commercial buildings, the flat roofs on condominium and apartment buildings, and the additions and porches that were tied into an older house.

Those are different buildings and the same problem. The membrane has to be continuous, the edges have to be fastened, and the water has to leave. A porch roof that dumps into a wall, or a condo roof that ponds at a clogged drain, fails for a local reason. The replacement is scoped to that reason, not to a package that ignores the drain.

This page is the replacement and installation side of flat roofing. If the roof can be repaired, that work is on the repair site, linked below, so the two jobs are not written as if they were one.

Commercial buildings with a low-slope membrane roof
Condominium and apartment roofs where one membrane covers more than one unit
Additions and porches tied into an existing house
Commercial roofing for building owners

Systems

Crews install TPO and EPDM, and they install roof coatings when a coating is the right restoration. Modified bitumen, the granulated or smooth cap sheet on many older flat roofs, is repaired and replaced when that is the system already there. Each membrane is detailed differently at the wall, the curb and the drain. Mixing the details is how a new roof leaks at the edge in the first year.

TPO and EPDM have their own page: how the sheets differ, how they are attached, and what heat and hail do to them. A coating is not a substitute for a wet roof; that decision is on the coating page. Metal, where a flat section meets a standing-seam or exposed-fastener roof, is on the metal page.

Replace, recover or repair

Three different scopes get confused because they all end with a dry building. A repair fixes failed seams, punctures, flashings or a drain, and leaves a sound membrane in place. A recover puts a new membrane over a dry roof that is still attached, when the deck can take it and the layers already on the roof allow it. A replacement tears the roof off to the deck, replaces wet insulation, and builds the slope and the membrane back.

Recover is not a way to hide a wet roof. If a core cut comes up wet, the insulation comes out. Stacking another membrane on saturated board traps the water and the deck pays for it later. Where the code at that address limits how many roofs can sit on top of each other, the scope is a tear-off even if the old membrane looks intact.

Repair is the other site's work. A flat roof that ponds, a split seam, a blister or a puncture starts there. If that visit shows the roof is finished, the replacement is written here.

What a flat roof replacement involves

We inspect the roof, photograph the seams, drains and flashings, and cut a test opening when the insulation may be wet.
The scope says tear-off or recover, and it lists the insulation, including tapered insulation where the roof has to be taught to drain.
Drainage is part of the roof, not an extra: drains, scuppers and the crickets that push water toward them.
Flashings at walls, curbs, pipes and the edge metal are detailed to the membrane, not caulked on at the end.
The timeline follows the size of the roof, the weather and whether the building stays open. We agree the sequence before the tear-off. We do not publish a number of days as a promise.

What changes the price

This page does not list prices. A flat roof replacement is priced in writing after we see the roof. What moves the number is visible, and it is the same list a building owner can use to compare two bids.

Size is the obvious one. Tear-off costs more than a recover because the old roof has to come off and leave the site. Wet insulation has to be replaced; dry insulation sometimes stays. Tapered insulation, the boards that create slope, is a real material line when the deck is dead flat. Every curb, pipe and wall is a flashing. A roof with a crowded mechanical yard has more of them. Access, the edge metal, and rotten decking found after the tear-off are the rest. A bid that is silent on those lines is not the same bid as one that names them.

Tear-off or recover, and whether the insulation is wet
Tapered insulation and drains where water stands
Penetrations, walls, edge metal, access and deck repair
A written scope after the inspection, not a price on this page

Heat, hail and ponding

St. Louis summers cook a low-slope roof. A light-colored membrane reflects more of that heat than a black one, which is one reason TPO shows up on buildings that run air conditioning hard. Heat is not only comfort. It ages the sheet and the sealants at every curb.

Hail is common enough that a flat roof should be looked at after a serious storm, not assumed fine because the ceiling is dry. Hail bruises a membrane, fractures an older coating and dents edge metal. A bruise is not always a leak today. It is a place that will crack later if nobody maps it.

Ponding is the condition we fix in the replacement, not the one we explain away. Water that is still standing many hours after the rain is sitting on the seams. A new membrane laid to the same slope will pond in the same place. The replacement either tapers the insulation or moves the water to a drain. If it does neither, it is a new roof with the old problem.

Hail and storm damage

Warranty

The warranty we state is a written labor and workmanship warranty. The term for a full replacement is not the term for a repair, and both are on the certificate for the job. We do not restate manufacturer system-warranty language on this page.

Insurance and workmanship details — Is your work covered by a warranty?

Questions about flat roofing

Is a flat roof supposed to hold water?: No. A low-slope roof is designed to drain. Water still standing long after the rain is ponding, and ponding shortens the membrane. The fix is often drainage and slope, not only a new sheet.
What is the difference between a recover and a tear-off?: A recover puts a new membrane over a dry, attached roof when the deck and the code at that address allow it. A tear-off takes the roof down to the deck, which is the right scope when the insulation is wet or the layers are already too many.
Do you install TPO and EPDM?: Yes. Both are single-ply membranes we install. They are detailed differently. The TPO and EPDM page explains the difference, including fully adhered and mechanically attached installation.
Can you coat a flat roof instead of replacing it?: Sometimes. A coating is a restoration of a dry, attached roof. It is the wrong product when a core cut shows wet insulation or the deck has failed. That choice is on the coating page.
My flat roof leaks. Do I start here?: Start with the repair site if you want the leak found and fixed. Come here when the roof needs to be replaced or you already know the membrane is finished. We will say which one it is after we look.
How long does a flat roof replacement take?: It depends on the size, the weather, the tear-off and whether the building stays open. The sequence is in the scope. We do not promise a number of days on this page.
What should I compare in two flat-roof bids?: Tear-off or recover, insulation and whether it is tapered, drains, flashings, edge metal and what happens if the deck is soft. Two totals are not comparable until those lines match.
Do you list a price for a flat roof?: No. The price is a written scope after we see the roof. This page only lists what usually changes that number.
Do I get photos from the inspection?: Yes. We photograph what we find and go through it with you, so you see what we saw.

Why building owners work with us

GAF Certified
BBB Accredited, rated A+ (read 28 Sep 2026)
We pull the permit on every job that requires one.
Our office reads every request and calls you back.
Inspections documented with photos of what we found.

Where we do this work

Jefferson County
St. Louis City
St. Louis County
St. Charles County

Municipality lists and who issues the permit

Flat roofing in St. Louis