PVC is the membrane for grease, chemicals and heat.

PVC is a hot-air welded thermoplastic, like TPO, and on a plain warehouse the two roofs behave much the same. The difference appears where the roof is asked to survive something. Grease from a kitchen exhaust, discharge from a process vent, or repeated chemical contact will degrade a membrane with no resistance to it. That is the case for PVC, and it is the only case worth making.

Compare this on your roof

A low-slope commercial roof at dusk, mechanical curbs silhouetted against a warm horizon.

At a glance

The system, before the sales pitch.

Specification first. Every row below is a property of the system, not a claim about a product line.

Restaurant roofs are a PVC conversation: Kitchen exhaust deposits animal fats across the membrane downwind of the fan. Fats soften sheets that have no resistance to them, and the damage appears as a degraded field rather than a failed seam. On those buildings we specify PVC and put the reason in writing.
It welds, and it keeps welding: PVC seams are fused with hot air. An old weld can be probed for continuity and remade with the same equipment years later. On a roof that will be reopened every time a rooftop unit is changed, that repeatability matters more than anything on the product sheet.
Where TPO is the right call instead: On a building with no grease, no chemical exposure and ordinary traffic, PVC buys a resistance the roof will never use. We will say so. A membrane specification should be defensible on the exposure the building actually has, not on the one that sells better.

A low-slope commercial roof field with mechanical curbs, a drain and welded seam lines.

How the system behaves

Performance is an assembly, not a product name.

A domed rooflight on a raised kerb in a white single-ply membrane roof, welded seams running across the field around it.

What we do at the exhaust fan

The field downwind of a kitchen fan takes the worst of it, and grease containment on the unit is part of the roofing conversation whether or not it falls inside our scope. Where the membrane there has already softened, that area is scoped separately rather than averaged into one condition across the whole roof.

Welding is a workmanship item

Weld quality depends on machine settings, membrane temperature, surface cleanliness and the person running the hand welder at every corner the automatic machine cannot reach. Seams are probed after they are made. Where a detail cannot be welded properly, it is flashed with a prefabricated accessory rather than improvised out of offcuts.

Compatibility with what is already there

PVC does not bond to TPO or EPDM, and it can react badly with asphalt-based materials and some insulation facers unless a separator is used. On a re-roof or a tie-in to an existing area, establishing what the new membrane is being asked to touch comes before anything is ordered.

Choose a starting point

Match the next step to the condition.

A short, non-diagnostic guide for working out what kind of assessment conversation to prepare for.

What best describes the property today?

Decision support

Choose a starting point.

Four situations, and the sensible next move for each. It does not diagnose a roof, decide insurance coverage, or stand in for somebody looking at the property.

What the next step actually is
What to have ready before anyone arrives
What we will not ask you to do

Questions

Useful answers, without overpromising.

Is PVC worth the premium over TPO?

On a building with grease or chemical exposure, the case is straightforward. On a plain roof with neither, the honest answer is usually no. The exposure decides it. Paying for chemical resistance a building will never call on is not a better roof, only a dearer one.

Can PVC go directly over an existing asphalt roof?

Not in direct contact. Asphalt can attack the membrane, so a separator sheet or a new insulation layer is required between them. That requirement is part of the assembly design and belongs in the scope before a number is attached to it.

Does a white PVC roof stay white?

No. Every reflective membrane collects dirt and loses some reflectivity in the early years, then settles. Cleaning recovers part of it. Any energy argument built on day-one reflectivity is describing a roof that will not exist by year five.

How do I tell PVC from TPO on a roof I did not have installed?

Usually not by looking. Both are hot-air welded thermoplastics, both are commonly white, and a repair made in the wrong one will not bond. The three routes to an answer are a field test on a small sample, the manufacturer's markings on the underside of the sheet where they have survived, and whatever documentation the building holds. It is settled before material is ordered rather than after a patch has lifted.

Assessment request

Tell us what is happening at the property.

Short, routing-only questions. Nothing here asks you to diagnose the roof yourself.