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Featured Product: Modified Bitumen

Commercial customers sometimes ask us about the modified bitumen we use for many flat roofs. As area leaders in this economical low-slope and flat-roof technology, we enjoy sharing our knowledge.

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. Unfortunately, plain bitumen is smelly, dirty and low in tensile strength.

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. BELDON® Roofing Company can get them up your Texas company’s roof by freight elevator, ladder hoist or, if necessary, by stairs. We lay the rolls out rapidly and seal their laps either using solvent (cold applied) or heat (torch applied).

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.


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
  • Initial Application
  • Proper Maintenance

Texas does not bring the punishing winter weather that can test a modified bitumen roof, but summer heat and ultraviolet rays from sunlight can degrade the material.

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. BELDON® Roofing Company 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.

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