Flat Roofing

  • Single Ply PVC / TPO / EPDM
  • Built up tar and gravel
  • Modified Bitumen / Torchdown

Selecting the correct Commercial Roofing application can be difficult. At RemStar we recognize that there is not one perfect roof system for every building. Our highly trained managers can guide you and help you make selections for the proper roofing system to fit the specific needs of your building. Whether it is Single Ply, Modified Bitumen, Conventional Built-Up or Metal, at RemStar, we have the solution.

Single Ply PVC / TPO / EPDM

  • Durability
  • Wind resistant
  • Flexible
  • Fire Resistant
  • Environmentally friendly

Types of Single Ply Membranes:

PVC (Polyvinyl Chloride)

Due to its durability, longevity and ability to withstand a build-up of chemicals, PVC is a widely used flat roofing system. PVC is also extremely easy to manufacture, install and repair. PVC membranes are manufactured from a combination of PVC resin, stabilizers, pigments, fillers, plasticizers, biocides, and various processing aids. Unlike TPO membranes, which require additives to increase fire resistance, PVC membranes are naturally fire retardant.

TPO (Thermoplastic Olefin)

Much like PVC, Thermoplastic Olefin is another commonly used material for a wide variety of flat roofing solutions. Due to the strong weatherproofing properties, TPO is often used when undertaking a green roof construction and has a life expectancy of around 20 years. TPO can be installed in a multitude of ways and with the introduction of peel-and-stick products, installation time can be reduced significantly. Like PVC, TPO remains hot-air weldable throughout its service life, simplifying repairs and maintenance.

EPDM (Ethylene Propylene Diene Terpolymer)

EPDM is a versatile and flexible single ply material that can be mechanically secured, ballasted as well as fully adhered. EPDM has excellent weathering qualities as it is 100% resistant to UV radiation, Ozone thermal shock and changing weather conditions. EPDM membranes are known for their long-term weathering ability and perform well even when subjected to fluctuations in temperature, ultraviolet rays, and ozone. The membranes are available in both unreinforced and reinforced, the latter of which increases resistance to tearing. EPDM is available in thicknesses and is offered in wider sheets that may be desirable.

Single Ply roofing membranes provide a variety of materials to choose from. Their main characteristic is that they are designed to be installed in one layer. They also exhibit great flexibility and their resistance to UV radiation is superior when compared to other products. It is usually black or white finish, and glued, fastened or installed directly over the roof insulation.


Single-ply membranes can be generally categorized into two groups – thermosets and thermoplastics.

  • Thermosets, or those materials that you can’t hot-air weld (EPDM) because it will change their physical characteristics, use a tape or a contact cement to make up the lap.
  • As opposed to thermosets, the seams on thermoplastic single-ply membranes can be hot-air welded together to form cohesive laps. When thermoplastic membranes cool, they return to their original material type. PVC and TPO are two of the most commonly installed thermoplastic single-ply membranes.

Built up Tar & Gravel

  • Economical
  • Impact resistant
  • Protection against UV rays
  • Fire Resistant

Types of Built-Up Roofing:

Tar & Gravel

Tar & Gravel systems use smaller more course rocks. The gravel used is about the size of 0.25″ – 0.5″ inches (0.64 cm -1.27 cm) in diameter.

Another key difference is that on Tar & Gravel roofs, the rocks are sealed down using a bitumen-based chemical.

The bitumen which seals down the gravel can come in two different forms cold applied and heat applied.

The cold applied can be easily spread because it is liquid at standard temperatures but hardens as it cures.

The hot-applied requires a torch to melt the bitumen, then it hardens as it cools.


Ballasted systems use larger rocks. The size of gravel can range anywhere from 1.5″ – 2.5″ inches (3.8 cm – 6.4 cm) in diameter.

The rocks in a ballasted roof system are not sealed, rather they are loosely piled on top of a waterproof membrane.

The waterproof membrane used is not sealed down to the roof but is held in place from the weight of the large stones resting on top of it.

Ballasted roof systems can have anywhere from a few inches of rocks to a foot of rocks.

A built-up roof (BUR) also known as a tar and gravel roof is a popular choice for low slope roof owners.

The built-up roof system is made up of multiple layers of various fabric materials. The fabric is layered by alternating a layer of durable fabric with a coat of bitumen (asphalt). Finally, the last layer is topped with rocks or gravel.

Building owners can choose how many layers they want in their roof system. Each layer will add about 5 years of life to the built-up roof.

Another way of looking at a built-up roof is to imagine that it’s like turning the entire roof into one giant shingle.

Modified Bitumen (Torchdown)

  • Flexibility and Durability
  • 15-20 year lifespan
  • Protection against UV rays
  • Fire Resistant
  • Easy Repairs

Each sheet of torch-down roofing material consists of multiple membranes stacked and adhered together. These are the membrane layers of torch down roofing material, from the bottom up:

Layer 1: Thermo-fusible film.

Layer 2: Modified bitumen.

Layer 3: Reinforced polyester.

Layer 4: Modified bitumen.

Layer 5: (For the third layer of a three-layer roof) Granulated mineral surface.

A compound known as modified bitumen makes up the second and fourth membrane layers of each sheet of torch-down roofing material. Bitumen is an asphalt compound. It is used in roofing and other construction applications like road construction and repair. Modified bitumen is asphalt bitumen mixed with a plastic or rubber additive. There are two main types of modified bitumen membrane that are used to create torch down roofing material: Atactic Polypropylene (APP) and Styrene Butadiene Styrene (SBS).

  • Atactic Polypropylene (APP)

APP is a type of plastic used to produce modified bitumen for torch down roofing. APP modified bitumen membranes are especially flexible. They respond well to both high and low temperatures.

  • Styrene Butadiene Styrene (SBS)

SBS is a type of rubber used to create modified bitumen for torch down roofing. SBS modified bitumen membranes are also flexible, and they have a lower melting point than APP membranes. This means that SBS membranes can be used in torch-down roofing, as well as self-adhering and cold-processed roofing systems.

Torch down roofing—also known as “torch on roofing”—is one of the most common types of roofing for flat and slightly sloped roofs. Torch down roofing consists of multiple modified bitumen membranes, applied with a propane torch. This installation process gives torch down roofing a uniquely watertight seal, making it a great choice wherever water damage is a serious concern.

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