Modified Bitumen Flat Roofing Membranes

flat roof replacement toronto

The Manufacturing Process

Bitumen is a heavy petroleum product. It is great for sealing out water, resisting changes in temperature, and providing long-lasting, flexible roof protection. Modified bitumen roofing material keeps all the best qualities of this petroleum product but modifies it by adding long-fiber rubber compounds or polymers for strength, elasticity and workability.

Sheets of modified bitumen roofing membrane are made in a factory under carefully controlled conditions and spun into convenient rolls. can get them up your flat roof by freight elevator, ladder hoist or, if necessary, by stairs. We lay the rolls out rapidly and seal their laps using heat welding (torch application).

Common modifiers mixed into the bitumen include:
Styrene-butadiene-styrene (SBS), a rubber
Atactic-polypropylene (APP), a plastic

Although we often refer to our products using these abbreviations, we are always happy to explain what our industry lingo means, and why either APP or SBS is the right choice for your commercial roof.


Your flat roof can take on just about any final appearance you would like, because the top of the membrane can be treated with granulated minerals or metal foils in a wide range of colors, including cool white to help lower cooling costs.


The Greater Toronto Area experiences punishing weather where modified bitumen roofs have been tried and tested. A well-designed, carefully installed modified bitumen flat roof can easily last more than a decade, and often two. The lifespan of your commercial roof depends on three factors:

  • Climate
  • Professional Installation
  • Proper Maintenance

Maintenance Requirements

Maintenance red flags for your membrane roof depend on the modifiers used:

SBS membranes—granule loss, blister, cracking, open or loose laps

APP membranes—blisters, loose bare flashings, crazing, cracking, and open or loose laps

Having professional, commercial roofers perform an annual inspection is economical, since small issues can be repaired efficiently before they become major problems or lead to leaks. can install your modified bitumen flat roof, help you maintain it, and advise your maintenance department on carrying out semi-annual or quarterly inspections and repairs. Give us a call, contact us today for a free estimate.

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