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TPO roofing

TPO (thermoplastic polyolefin) is a single-ply membrane for low-slope commercial roofs, used on new buildings and reroofs. Each sheet is a polyester fabric sealed between two plies of TPO, and the overlaps between sheets are fused with hot air rather than glued.

Warranty available
Up to 30 years from manufacturers, on 80-mil sheet
Common thicknesses
45, 60 or 80 mil
Seams
Hot-air welded
Surface
White, tan or gray as standard; white reflects most
Attachment
Fastened, adhered, induction-welded or ballasted

How it's installed

The deck, the layers under the membrane and the building decide the method. The choice also changes which warranty terms a manufacturer will offer.

Mechanically attached

Rows of screws and plates hold one edge of each sheet to the deck, and the next sheet laps over the row and is welded shut. Corners and perimeters can need extra fasteners.

Fully adhered

Adhesive bonds the whole sheet to insulation or a cover board, and self-adhered sheets arrive with the adhesive applied at the factory. The Defense Department's TPO guide specification calls an adhered sheet over a cover board the preferred norm.

Induction-welded

Plates are fastened to the deck first, the sheet is rolled out over them, and an induction tool set on top welds the underside of the sheet to each plate.

Ballasted

In Carlisle's ICC-ES evaluation report, river stone or pavers hold the sheet down, with the ballast designed for wind under the ANSI/SPRI RP-4 guide. A design professional has to certify that the structure can carry the load.

Pros and cons

Where TPO wins

  • Welded seams fuse into one continuous sheet, and a crew can check each weld on the roof by probing it.
  • White sheet stays reflective as it weathers: two manufacturers list 0.77 to 0.79 solar reflectance new and 0.70 after three years.
  • Field rolls run up to 12 feet wide, and 16 from one maker, so large roofs have fewer seams to weld and inspect.
  • Self-adhered sheets with factory-applied adhesive cut odor and VOCs, which helps on occupied buildings.

Where it falls short

  • Weld quality depends on the welder's heat and speed, so seams have to be probed and fixed every working day.
  • Repairs on an older roof take prep: weathered sheet must be cleaned before new material will weld to it.
  • The 45-mil sheet caps the warranty (15 years at Johns Manville, 30 for 80-mil) and passed less than half the impact of 80-mil in Carlisle's puncture test.
  • Where a roof sees heavy grease, chemicals or puncture risk, Elevate says PVC may be the better choice.

TPO and hail

FM Approvals rates the whole assembly for hail under its 4470 standard, not the membrane alone, and every approved assembly is at least Moderate Hail (MH). MH and Severe Hail (SH) drop a 2-inch steel ball for about 8 and 14 ft-lb; Very Severe Hail (VSH) fires 2-inch ice balls at 53 to 58 ft-lb, and the board under the membrane must not crack. The VSH-rated TPO assemblies in Johns Manville's brochure all sit on a reinforced gypsum cover board. FM Global Data Sheet 1-34 maps the regions where FM recommends each rating.

Thickness and attachment matter too. In Carlisle's puncture tests, 45-mil sheet stayed watertight after 9.2 ft-lb of impact, 60-mil after 16.6 and 80-mil after 22.1, and Johns Manville's mechanically attached VSH assemblies use 80-mil. VSH testing also strikes a field seam and, on fastened roofs, a fastener plate, so those details are part of the rating. If you're reroofing in hail country, ask for the FM assembly's hail rating, not just the membrane's.

Compare TPO

  • TPO vs EPDM
    TPO vs EPDM side by side: welded or taped seams, white or black sheet, roll widths, cold and grease resistance, warranties, and when to pick each.
  • TPO vs PVC
    TPO vs PVC side by side: both are welded thermoplastics, but PVC resists grease and oils and has to be kept off asphalt. Warranties and when to pick each.

Back to all roof systems

Sources

  1. Elevate (Amrize Building Envelope), UltraPly TPO Roofing Systems
  2. Carlisle SynTec Systems, Sure-Weld TPO Reinforced Membrane Product Data Sheet (01.28.26)
  3. Johns Manville, JM TPO Roofing Membrane
  4. USACE / NAVFAC / AFCEC (Whole Building Design Guide), UFGS 07 54 23 Thermoplastic-Polyolefin Roofing (August 2025)
  5. Johns Manville, JM TPO 80 mil Thermoplastic Polyolefin Membrane data sheet (RS-8634)
  6. Carlisle SynTec Systems, TPO Fully Adhered 25- and 30-year Warranty Submittal Sheet
  7. Elevate (Amrize Building Envelope), UltraPly Platinum TPO System
  8. Johns Manville, JM TPO 45 mil Thermoplastic Polyolefin Membrane data sheet (RS-8632)
  9. ICC Evaluation Service, ESR-1184: Carlisle Ballasted Single-Ply Roofing Systems, EPDM and TPO membranes (revised May 2026)
  10. Johns Manville, JM TPO 60 mil Thermoplastic Polyolefin Membrane data sheet (RS-8633)
  11. Elevate (Amrize Building Envelope), UltraPly TPO Roofing Systems: membrane
  12. Johns Manville, JM Very Severe Hail Solutions (RS-1749)
  13. Johns Manville, JM TPO SA - 60 mil
  14. Versico Roofing Systems, Seam Probing
  15. FM Approvals, Examination Standard for Single-Ply, Polymer-Modified Bitumen Sheet, Built-Up Roof (BUR) and Liquid Applied Roof Assemblies, Class Number 4470 (April 2022)
  16. Carlisle SynTec Systems, FM's VSH Testing: Very Severe Hail (updated August 2025)

Updated October 2026.