Carlisle TPO, EPDM and PVC Flat Roof Membranes We Install

Product lines

Sure-Weld TPO, Sure-Seal EPDM and Sure-Flex PVC compared

All three are single-ply membranes: one waterproof sheet laid over insulation or a cover board, with seams sealed so the whole roof acts as one surface. The difference is chemistry and how the seams are made.

• Sure-Weld TPO is Carlisle’s TPO, a thermoplastic. TPO seams are melted together with a hot-air welder, so a good weld fuses two sheets into one. Standard white TPO reflects sunlight.
• Sure-Seal EPDM is Carlisle’s EPDM, a synthetic rubber that is usually black. EPDM seams are bonded with primer and seam tape rather than heat. It is the long-standing workhorse of low-slope roofing.
• Sure-Flex PVC is Carlisle’s PVC. Like TPO it is heat-welded, and PVC is typically specified where kitchen exhaust, oils or certain chemicals land on the roof.

Our flat roof membranes guide compares these with modified bitumen and other low-slope options.

Choosing Carlisle TPO, EPDM or PVC for a low-slope roof

For a small residential flat roof, the choice usually comes down to EPDM versus TPO. EPDM handles cold-weather flexing well and is simple to repair with patches. TPO’s welded seams are very durable, and its white surface keeps an upstairs room over a flat roof cooler in July. If a deck, rooftop units or heavy foot traffic will be on the roof, walkway pads and a thicker membrane matter more than the brand.

On commercial buildings, insulation and drainage drive the decision as much as the membrane. Tapered insulation that moves water to drains, cover boards that resist foot traffic, and the energy code’s insulation requirements for a full reroof all shape the specification. Our flat roofing and commercial roofing pages cover those choices in more depth.

Carlisle membranes under Chicago snow, ponding and summer sun

Low-slope roofs here face problems a pitched roof sheds. Snow sits rather than slides, adding weight and feeding meltwater toward drains that may be frozen. Water that stays on the roof long after a storm, called ponding, signals poor slope or clogged drains, and it is where membranes age fastest. Freeze-thaw cycles open any weak seam or flashing detail.

The practical defenses are the same whichever Carlisle membrane you choose: enough slope, often through tapered insulation; drains and scuppers kept clear; well-detailed flashing at walls, curbs and penetrations; and a cover board that protects the insulation from foot traffic during snow removal. Most flat-roof leaks start at flashings and penetrations, not in the open field of the membrane.

Six specs a Carlisle flat-roof proposal should state

1. Membrane and thickness: Sure-Weld TPO, Sure-Seal EPDM or Sure-Flex PVC, with thickness in mils.
2. Attachment method: fully adhered, mechanically attached or ballasted. Each affects wind performance and cost.
3. Insulation: type, total thickness, any tapered layout, and whether a cover board is included.
4. Tear-off or recover: whether existing layers come off, and how wet insulation will be found and replaced.
5. Flashing details: walls, curbs, drains, edge metal and penetrations.
6. Warranty type: membrane-only or full system, the term, and whether a Carlisle inspection is part of it.

How Carlisle SynTec warranties are structured

Low-slope warranties come in two broad kinds: coverage for the membrane alone, and system coverage for the membrane, insulation and accessories as one assembly. Ask which kind a Carlisle proposal includes. For system coverage, also ask whether it is available only through contractors the manufacturer has certified as authorized applicators, and what it requires, such as Carlisle-supplied components, project paperwork and a manufacturer inspection once the roof is finished. Term and wind coverage generally depend on the specification, including membrane thickness and attachment method. The current options are published at carlislesyntec.com.

ALTA installs Carlisle SynTec products. We do not currently hold a Carlisle SynTec manufacturer credential, so enhanced warranties that require one are not offered on our installations; your estimate names the warranty that applies.

Where Carlisle SynTec fits best

• Flat porch roofs, rear additions and garages attached to pitched-roof homes
• Condo, townhome and small commercial buildings that need a documented system warranty
• Low-slope roofs where the choice between reflective TPO and cold-flexible EPDM matters

Product information last reviewed November 5, 2026. Always confirm current specifications and warranty terms at carlislesyntec.com.

Carlisle SynTec questions

Should I choose Carlisle Sure-Weld or Sure-Seal for a porch or addition roof?

Sure-Seal EPDM stays flexible through Chicago winters and is simple to patch, which suits a small roof that sees little foot traffic. Sure-Weld TPO has heat-welded seams and a white surface that keeps a room below cooler in summer. On a roof that small, drainage and the flashing at the house wall decide more than the membrane does.

Can a new Carlisle membrane go over my existing flat roof?

Sometimes. A recover is possible when the existing roof is dry and the building has not reached its code limit on roof layers. Wet insulation has to come out first, because trapped moisture ruins the new system from below. Core samples or a moisture survey settle the question.

Does Carlisle make roofing for homes, or only commercial buildings?

Carlisle membranes are used on both. On houses they typically cover porch roofs, additions, garages and other low-slope sections that shingles cannot protect, since shingles need more pitch to shed water.