Modified Bitumen, also commonly known as just “Modified” or “APP or SBS Membranes”. At Summers Roofing we mainly use GAF® Ruberoid®, however, we are also certified installers of Firestone, Mule-Hide, and CertainTeed. For purposes of this web page we’ll be showcasing all GAF® products.
What exactly is Modified Bitumen?

Essentially modified bitumen is base and cap sheets that can be hot asphalt applied, torch applied, or cold process applied (mop down). Your base sheet is usually determined by the type of cap sheet you choose, and just like shingles there are several different types of cap sheets to choose from. Examples below. For a number of years now we have seen architects start to lean more towards the torch applied system, therefore that’s what we are going to discuss on this page.
Types – Torch Down Modified
Several other product types are available by a wide range of manufacturers. Here are a couple of the most used by Summers Roofing.
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RUBEROID® Torch Smooth Membrane
“Its core is a strong, resilient non-woven polyester mat that is coated with weather-resistant, APP polymer-modified asphalt. The membrane is available with a smooth surface. RUBEROID® TORCH SMOOTH Membrane is backed by GAF, a company with over 130 years in the roofing business.”
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RUBEROID® Torch Granule Membrane
“Its core is a strong, resilient, non-woven polyester mat that is coated with weather-resistant APP polymer modified asphalt.”
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RUBEROID® Torch Plus Granule FR Membrane
“RUBEROID® TORCH PLUS GRANULE FR Membrane is a strong, heavyweight, resilient non-woven polyester mat that is coated with an inherently fire-retardant APP polymer modified asphalt and surfaced with mineral granules. RUBEROID® TORCH PLUS GRANULE FR Membrane is backed by GAF, a company with over 130 years in the roofing business.”
Typical Uses
There are other products on the market for these uses, but Ruberoid® Torch Membrane is among the thickest at 0.148″, making is harder to fully puncture than most alternative products.
- Decks – Modified is a great choice under floating decks.
- Crickets and Dead Valleys
- Flat Roof Systems
- Low Sloped Roofs – If your roof doesn’t have enough pitch for shingles then modified would be a good option, particularly Granulated due to its finished look in a variety of colors.
Benefits – Torch Smooth
- Typical system guarantees available for up to 15 years; select system constructions available with up to 20-year guarantee coverage
- Installed roof designs weigh less than 2 pounds per square foot
- RUBEROID® TORCH SMOOTH Membrane polyester mat core allows it to resist splits and tears due to its pliability and elongation characteristics
- Specially formulated modified asphalt for lasting performance
Benefits – Torch Plus Granule FR
- Available Guarantees: System guarantees are available for up to 20 years
- No Coating Required: For Class A roofing fire rating from UL and FMRC
- Cost Effective: The installed cost of RUBEROID® TORCH PLUS GRANULE FR Membrane is less than most single-ply systems on the market today
- Lightweight: Installed premium roof designs weigh less than 3 pounds per square foot
- Resilient: RUBEROID® TORCH PLUS GRANULE FR Membrane’s heavyweight polyester mat core allows it to resist splits and tears due to its pliability and elongation characteristics
- Durable: Specially formulated modified asphalt gives RUBEROID® TORCH PLUS GRANULE FR Membrane lasting performance
- Wind Uplift Resistance: Selected roofing assemblies with RUBEROID® TORCH PLUS GRANULE FR Membrane meets FMRC Class 1-180 when installed over concrete decks