A single ply roof membrane system covers a low-slope roof with one layer of flexible sheet material instead of the multiple plies used in built-up or modified bitumen roofs. The three membranes you’ll see most often are TPO, PVC, and EPDM, and each one behaves a little differently in Savannah’s heat, humidity, and storm season. If you’re comparing options for a warehouse, retail building, or office, our TPO roofing system is a common starting point, but the right choice depends on the building.
How a Single Ply Roof Membrane System Is Built
The membrane is only the top layer. Underneath it, a typical system includes the roof deck, rigid insulation, and sometimes a cover board that protects the insulation and gives the membrane a smooth, firm surface. Flashing at walls, curbs, and penetrations ties the membrane into everything else on the roof, and edge metal finishes the perimeter.
On a replacement, insulation also has a code requirement to meet. Georgia applies its commercial energy code to roof replacements as well as new buildings when the insulation sits entirely above the deck, and the 2020 Georgia code set that minimum at R-25 for the coastal climate zones. An older roof with thin insulation may need a thicker layer when the membrane is replaced.
TPO, PVC, and EPDM Compared
TPO and PVC are thermoplastic membranes. Their seams are joined with hot air, which melts the edges of overlapping sheets together into a continuous bond. Both usually come in white, and that reflective surface keeps the roof cooler in summer sun than a dark membrane would. Dirt and biological growth can dull a white membrane over time, so keeping the surface reasonably clean helps it keep reflecting heat the way it did when it was new. PVC holds up better where a roof is exposed to grease or certain chemicals, which is why it often shows up on restaurants and some industrial buildings.
EPDM is a synthetic rubber membrane, and it’s a thermoset, so its seams can’t be heat-welded. Installers join EPDM sheets with seam tape and adhesives instead. EPDM has a long track record on low-slope roofs and stays flexible across temperature swings. It’s most often black, though white versions exist. Our EPDM roofing covers new installs and repairs on existing rubber roofs, and our breakdown of TPO vs. EPDM vs. PVC Roofing goes deeper into cost and performance differences.
How the Single Ply Roof Membrane Is Attached
There are four common ways to secure a single-ply membrane, and the choice affects wind performance, cost, and how the roof handles future repairs.
Mechanically attached
Screws and plates fasten the membrane through the insulation into the deck, and the next sheet overlaps and covers the fasteners. This method is fast and economical. Under strong wind uplift, though, the membrane can billow between fastener rows.
Fully adhered
Adhesive bonds the membrane to the insulation or cover board across its whole surface. There are no fastener plates in the membrane, and wind pressure is spread evenly, which gives fully adhered systems strong uplift resistance. Adhesives do have minimum temperature limits, which matters less in Savannah than in colder climates.
Induction welded
Plates hold down the insulation, and an induction tool then bonds the underside of a TPO or PVC membrane to those plates. It avoids exposed fasteners and reduces billowing.
Ballasted
The membrane is loose-laid and held down with stone or pavers. The International Building Code doesn’t allow aggregate ballast on buildings in hurricane-prone regions, so owners on the coast need to confirm their site’s classification before considering it.
Signs a Single-Ply Roof Needs Attention
Problems on single-ply roofs tend to start at seams, flashing, and penetrations. Watch for open or wrinkled seams, flashing that has pulled away at walls and curbs, punctures from foot traffic or dropped tools, and ponding water that stays on the roof well after a storm. On mechanically attached roofs, fastener plates showing through the membrane can mean the plates have backed out.
In Savannah, summer thunderstorms and tropical systems put seams and flashing under heavy wind and rain. A commercial roof inspection after a major storm can catch a lifted edge or open seam before water reaches the insulation. Once insulation is wet, a repair gets larger and more expensive.
Should You Repair, Coat, or Replace Your Commercial Roof?
A single-ply membrane with isolated damage can usually be patched. TPO and PVC repairs use heat-welded patches of matching membrane, and EPDM repairs use compatible tapes and adhesives. When the membrane is aging but still sound, a silicone roof coating can be applied over it to extend its life without a tear-off. When leaks keep returning across large areas or the insulation underneath is saturated, a full commercial roof replacement is usually the better investment.
Working With WaterTite Commercial Roofing
WaterTite Commercial Roofing installs and repairs TPO, PVC, and EPDM roofs on commercial, agricultural, and industrial buildings around Savannah. We have six years on the commercial side and more than 20 years of roofing industry experience. All of our contractors are Conklin certified, we’re licensed and insured, and we use the highest quality materials on every system. During replacements we also install rooftop insulation, including polyolefin insulation, so the new membrane sits on an assembly that meets current requirements.
Every project starts with a drone inspection, and you’ll get a free estimate within 24 hours. Our pricing is upfront and transparent. Roofs we install carry a standard 5-year workmanship warranty, and if you schedule an annual inspection with us, we’ll extend that workmanship warranty to match the membrane’s material warranty. Every roof replacement includes free gutter cleaning, and if storm damage is involved, our crews are storm damage restoration experts who will walk you through the insurance process.
If you’re weighing a single ply roof membrane system for your building, we install all three membranes as a commercial roofing company in Savannah, and we’ll recommend the membrane and attachment method that fit your roof. Contact us to schedule your free drone inspection.
