flat roof

Types of Flat Roof Systems

Do you know what materials make up the roof on your commercial building? A wide range of roofing systems and material components exist, and the type of flat or low-slope roof your commercial building has matters. Factors such as energy efficiency, durability, and whether your particular roof is susceptible to specific issues like ponding water or damage from foot traffic are directly related to its materials and construction.

Today’s post offers a closer look at some of the most popular systems out there so you can better understand what repair and restoration options will be best as your commercial roof ages.

Asphalt Roofing Systems

Also called “tar and gravel” roofing, asphalt-based roofing systems have been around for decades. If your business is in an older building in an urban area, it’s likely to have an asphalt roof, though these systems are budget-friendly and still newly installed in some situations today. Don’t confuse commercial asphalt systems with asphalt shingles, however—shingles are widely used in residential applications, but it’s highly unlikely that your commercial roof is made from shingles.

Built-Up Roofing (BUR)

Built-up roofing, or BUR, is an asphalt-based system that’s been in use since the late 1800s. It features a continuous and semi-flexible membrane that consists of felt or fabric layers (known as “plies”) alternated with layers of other materials like tar/bitumen and aggregate.

If your roof has a layer of small stones or gravel covering its surface, it is most likely a BUR system, though these roofs do not necessarily have to have a gravel top layer.

Modified Bitumen (MB or “Mod Bit”)

Developed in Europe in the 1960s, MB roofing made its way to the USA in the 1970s and is considered a more technologically advanced version of BUR. It is often installed as a two-ply system, but many roofing contractors will install it as a single-ply membrane. (This doesn’t make it the same as the newer single-ply membrane systems we’ll cover next, however—those systems are not asphalt-based.)

MB roofing has a “rubberized” appearance and properties that lead many to call these systems “rubber roofs.” They are actually made from reinforced fabrics covered with asphalt-containing modifiers that give the material its elasticity.

Single-Ply Membranes

An extremely popular option today, single-ply membrane roofing is applied in one layer over board stock. In new installations, this stock is typically the roof deck itself, though single-ply membranes are an excellent restoration solution, too.

These membranes are made from either “thermoplastic” (changes rigidity as it heats and cools) or “thermoset” (not affected by temperature changes) material depending on the specific needs of a given building or business owner. Both types of membranes are often reflective and can offer significant energy savings over time. They also provide superior waterproofness.

TPO & PVC/Thermoplastic

TPO, which stands for thermoplastic polyolefin, and PVC, which stands for polyvinyl chloride are both materials that naturally expand and contract with temperature changes. This flexibility allows for excellent weathering capabilities plus resistance to UV (sun) light, punctures, and many chemicals, including oils, animal fats, and bacteria that tend to vent from businesses like restaurants.

EPDM/Thermoset materials

EPDM stands for the chemical name of the single-ply material that makes up some membrane roofs—Ethylene Propylene Diene Monomer. Because of its thermoset nature, this material is resistant to thermal stress, which refers to damage caused by natural temperature changes in the environment surrounding your roof and building.                        

Metal Roofing

Commercial metal roofs are generally made from affordable steel or aluminum. They are desirable for their eco-friendliness, energy efficiency, and durability.

While metal roofing does tend to have weak points, like the development of rust and corrosion over time, it is not difficult for professionals like us here at Unlimited Commercial Roofing to restore commercial metal roofs. This means metal roofing can be very long-lasting, and while the price of a newly installed metal roof is often a bit higher than some other systems, it can be worth it based on longevity.

Polyurethane Spray Foam

Like single-ply membrane systems, polyurethane spray foam roof coatings are versatile and can be utilized for new installations and as a restoration option. Also known as SPF systems, spray foam offers unique benefits most other systems don’t—namely substantial insulation value.

SPF is installed in layers, and the base is applied to be about 1″ thick to cover your entire roof and provide excellent insulation. SPF is also easy to renew and refresh over time by simply adding additional layers on top of older ones.

Let us help you choose the right restoration system for your current roof

Our focus at Unlimited Commercial Roofing is the restoration of aging commercial roofs that have developed pesky problems and leaks. Restoration is an affordable choice compared to total replacement or even patchwork repairs that don’t last for more than a season or two. Get in touch with us today to schedule an inspection of your eastern Pennsylvania or northern Maryland commercial building’s roof—even if you are not entirely sure what it’s made of! Unlimited Commercial Roofing can recommend a restoration option that will stop leaks and vastly improve performance.