This post is part of our series of blog posts about the pros and cons of the most popular types of commercial roofs: TPO, EPDM , metal, slate and tile, vegetative, and, this month, asphalt. As a property manager or owner, the more you know about your particular roof and the options available, the better!
You can also see our Guide To Commercial Roofing Systems: Pros and Cons that covers the highlights of each system in a PDF you can view online or download.
Asphalt Commercial Roofs
Asphalt historically has been one of the most popular types of commercial roofs because they work well and are very durable. Typically used on low-slope structures, asphalt commercial roofs consist of several layers — including a weather-proofing layer, one or more reinforcement layers, and a protective surface layer. Conceptually, asphalt roofs on low-slope commercial buildings are similar to asphalt shingle roofs on steep-slope buildings in that they are comprised of layers of materials that make them strong and weather-resistant.
Asphalt commercial roofs fit two broad categories:
- Built-Up Roofing (BUR) – Layers can include a vapor retarder, insulation, membrane (made of layered components adhered and waterproofed with asphalt) and surfacing material — all assembled at the job site.
- Modified Bitumen Systems (MBS) – A modified polymer adds strength and gives this system its name. The high-quality system is assembled at the factory and can be installed in a single ply, or in multiple plies similar to BUR. The MBS product often has a factory applied surfacing.
Other options for asphalt commercial roofs include integrating materials such as asphalt and gravel surfacing, fiberglass, aluminum, copper, minerals and different grades of bitumen. Your roofing professional will help you make the best choices for your building, climate, needs and budget.
Asphalt roofing systems provide exceptional performance and are known for being a moderate-cost but durable option. They also offer:
- Multi-layer protection
- UV and fire protection
- Uplift protection
- Easy maintenance
- Long warranties
- Many options and materials to choose from
Each category of system also offers its own advantages. For example, BUR offers especially good water resistance by nature of redundancy, uplift resistance and resistance to daily wear and tear for roofs that get a lot of foot traffic. Its strong insular qualities can make your building more energy efficient. MBS offers increased strength and flexibility and works well in all climates.
Just because asphalt commercial roofs are common doesn’t mean they’re right for every building. Installation can be tricky to ensure proper performance. Specialized equipment and expertise are required to install these systems.
BUR’s are typically constructed on the roof surface with hot bitumen (asphalt) at or above 400 degrees. The crew must get the hot bitumen to the rooftop and install it at the application site before it cools off. Today, cold adhesives are often used in lieu of hot asphalt, and some MBS systems use open-flame heat welding to adhere asphalt that was pre-applied at the factory.
If a roofing system requires hot asphalt or an open flame, your contractor will need to create a site-specific safety plan!
Warranties are available for 10 to 25 years, depending upon the asphalt commercial roofing system you select. Warranty coverage limits also vary from manufacturer to manufacturer so make sure you discuss what’s best for your goals with your roofing professional.
Sentry Roof Services has 30+ years experience re-roofing all types of roofs, including asphalt commercial roofs. The asphalt roofs we install are made from materials we’ve seen perform the best using techniques that we’ve refined. If you have any questions about an existing asphalt roof or a re-roofing project, please give us a call — we’d be happy to discuss your needs and offer advice.