What ASTM standards cover TPO, PVC and EPDM membranes?

ASTM D6878 covers thermoplastic polyolefin (TPO) sheet roofing, ASTM D4434 covers poly(vinyl chloride) sheet roofing, and ASTM D4637 covers EPDM sheet, which comes as non-reinforced Type I, reinforced Type II or fabric-backed Type III. All three are cited in the NYC Building Code: D4637 in BC 1507.12.2, and D4434 and D6878 in BC 1507.13.2. ASTM states that in-place design criteria such as fire resistance and wind uplift are outside the scope of the D4434 and D4637 sheet specifications.

Can a built-up roof in NYC use a gravel surface?

Not as the code reads. BC 1504.8 states that aggregate, gravel or crushed stone shall not be used as surfacing for roof coverings. Built-up roofs are covered by BC 1507.10, which requires a slope designed to provide positive roof drainage and materials that comply with UL 55A or the ASTM standards in Table 1507.10.2. Confirm the surfacing with the registered design professional before specifying.

What is fluid-applied roofing and where does it make sense?

Fluid-applied roofing is a liquid membrane cured in place, covered by BC 1507.15 with its own list of ASTM standards. Johns Manville describes its PMMA system as two-component and fast-curing, combined with a scrim to form a monolithic reinforced membrane, and says it suits confined urban space, numerous roof penetrations, or sites where hot asphalt or heat welding is restricted. Altius CM installed a reinforced fluid-applied roof across 28,000 sq ft at 1251 Avenue of the Americas.

What roof reflectance does NYC require for a flat roof?

BC 1504.9 requires roof coverings on slopes of 2:12 or less to have a minimum initial solar reflectance of 0.7 and thermal emittance of 0.75, or a minimum SRI of 82. Exceptions include green roof areas and terraces on setbacks under 25 percent of the largest floor plate, and a walking surface on roof recreation space needs only an initial reflectance of 0.3. DOB states that all NYC roofs must be cool roofs, with some exceptions.

ROOFING

Flat Roof Systems Compared: TPO, PVC, EPDM, Modified Bitumen, Built-Up and Fluid-Applied

Q: Which flat roof system is best for a commercial building?

None wins on every building. The NYC Building Code accepts built-up, modified bitumen, thermoset single-ply (EPDM), thermoplastic single-ply (TPO and PVC), sprayed polyurethane foam and liquid-applied roofing, each in its own section of BC 1507, so the choice comes down to the deck, the number of penetrations, the access and any limits on hot work, plus the warranty the manufacturer will issue. Every system must also provide positive drainage and meet the reflectance rule in BC 1504.9.

Published November 8, 2026

Which flat roof system is best for a commercial building?

None of them wins on every building. The NYC Building Code gives built-up, modified bitumen, thermoset single-ply, thermoplastic single-ply, sprayed foam and liquid-applied roofing their own sections, and the right pick comes from the deck, the penetrations, the access and the warranty you can get. This guide covers the six most often specified: TPO, PVC, EPDM, modified bitumen, built-up and fluid-applied.

We install more than one of these and do not sell a favorite. What follows sticks to the code, the ASTM standards and what manufacturers publish about their own products.

What does the NYC Building Code require of every system?

Chapter 15 of the 2022 NYC Building Code sets rules that apply no matter which membrane you pick:

Positive drainage. Each system’s section (BC 1507.10 to 1507.15) requires a slope designed and built to provide positive roof drainage.
Reflectance. BC 1504.9 requires a minimum initial solar reflectance of 0.7 with thermal emittance of 0.75, or an SRI of at least 82, on roofs of 2:12 slope or less. Terraces on setbacks under 25 percent of the largest floor plate and green roof areas are exempt, and a walking surface on roof recreation space needs 0.3.
No gravel surfacing. BC 1504.8 bars aggregate, gravel or crushed stone as surfacing.
Weathering and impact. BC 1504.6 requires low-slope coverings to show physical integrity after 2,000 hours of accelerated weathering, and BC 1504.7 requires impact resistance by listed tests.
Edge metal. BC 1504.5 requires metal edge securement to be designed for wind loads and tested to ANSI/SPRI/FM 4435 ES-1.
Ballast. Ballasted single-ply roofs must be designed to ANSI/SPRI RP-4 and stay within BC 1504.8 (BC 1504.4).

How do TPO, PVC and EPDM single-ply membranes differ?

All three are factory-made sheets. The code splits them into two groups: EPDM is thermoset (BC 1507.12, ASTM D4637), while TPO and PVC are thermoplastic (BC 1507.13, ASTM D6878 and D4434).

TPO. ASTM D6878 covers reinforced sheet with thermoplastic polyolefin as the principal polymer, and requires the sheet to be capable of being heat welded, fused or adhesively bonded to itself for watertight field splices and repairs.
PVC. ASTM D4434 covers fiber- or fabric-reinforced PVC sheet. Carlisle notes the standard requires a minimum of 16 mils of material over the scrim.
EPDM. ASTM D4637 covers vulcanized EPDM in three types: non-reinforced (I), scrim-reinforced (II) and fabric-backed (III).

Two limits matter when comparing data sheets. ASTM says in-place design criteria such as fire resistance, material compatibility and wind uplift are beyond the scope of the D4434 and D4637 specifications, so a sheet that meets the standard is not a tested roof assembly. Carlisle’s explainer on the ASTM hierarchy also shows why data sheets must cite the primary membrane standard to be comparable.

Manufacturer literature adds detail. Johns Manville says its PVC membranes are heat weldable and resist harsh chemicals and industrial pollutants, and lists its non-reinforced EPDM with factory inseam tape in 45, 60 and 90 mil. Those are manufacturer claims, not code requirements.

What are modified bitumen and built-up roofs?

Both are bitumen-based and layered. A built-up roof is, in Johns Manville’s words, “field-fabricated with layers of bitumen, alternating with plies of reinforcing felts.” Modified bitumen sheets come with glass, polyester or composite reinforcement; JM calls its SBS line the most customizable of its low-slope products.

The code treats them separately. Built-up roofs follow BC 1507.10 with UL 55A or the Table 1507.10.2 standards. Modified bitumen follows BC 1507.11 and ASTM D6162, D6163, D6164, D6222, D6223, D6298 or D6509, or CGSB 37-GP-56M. Because BC 1504.8 bars gravel surfacing, the finish on a NYC built-up roof has to be something else, so settle surfacing and reflectance on the drawings.

What is fluid-applied roofing?

A liquid membrane is applied in place, usually with reinforcement, and cures into a seamless layer. BC 1507.15 covers it and lists ASTM C836, C957, D1227, D3468, D6083, D6694 and D6947.

Johns Manville describes its PMMA roofing as a two-component, fast-curing system that combines resin, catalyst and scrim into a monolithic reinforced membrane, with the scrim improving tear strength, puncture resistance and crack bridging. It says the system is ideal for a confined urban space, numerous roof penetrations, or restrictions on hot asphalt or heat welding.

Altius CM used this approach at 1251 Avenue of the Americas, a 28,000 sq ft reinforced fluid-applied roof with associated flashings and new sheet metal. At 401 East 65th Street a liquid-applied membrane went over vacuum insulation with pavers after a tear-off of 6,500 sq ft. Our PMMA page lists more.

How do you choose between them?

Work through the constraints in this order:

Code first. Confirm reflectance, drainage and surfacing for the finished roof, including pavers.
Penetrations and detail density. A roof crowded with equipment and dunnage favors systems that detail around obstructions without seams.
Hot work and welding limits. If hot asphalt or heat welding is restricted, that removes some options before price is discussed.
Warranty terms. Manufacturers set approval, inspection and maintenance conditions by system; see roof warranties explained.
Drainage. Ponded water is a design, structural and warranty issue for every membrane; see drains, ponding and parapet flashing.

At 311 Franklin Avenue, Altius CM designed and built tapered insulation and installed a 2-ply roofing system with liquid flashing and metal work. The same team can price more than one system for your roof. See roof repair and replacement and our roofing hub, or read the replacement process and permits.

Why are there no cost or lifespan numbers here?

The primary sources above do not publish comparable installed costs or service lives for these systems, and a number without a source is a guess. Ask each bidder for the manufacturer’s published terms, the system’s ASTM and code references, and project references of the same type and size. A proposal that cannot name the standard its membrane meets is not ready to compare.

Sources

Last verified: November 8, 2026. Manufacturer statements are the manufacturers’ own descriptions of their products. This is general information, not a specification; have a registered design professional confirm the system for your roof.

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