Commercial Roofing Questions and Answers
For answers to commercial roofing questions, read on. To find a commercial roofing contractor serving your Hometown, search for your city in the "Find a Roofer" box.
What are the most common types of commercial roofing?
There are five primary classifications of low-slope commercial roof systems:
- Built-up commercial roofs
- Commercial metal roofing
- Polymer-modified bitumen sheet membranes
- Single-ply membranes (EPDM, TPO, PVC)
- Spray polyurethane foam (SPF)
Singly-ply roofing systems are the most widely used commercial roofing system in the United States. This includes EPDM, TPO or PVC roofing systems. A single-ply system offers durability and is a cost-effective choice. Commercial metal roofing offers increased durability over a single-ply system, although the cost of a metal roofing system is typically much higher.
What is EPDM roofing?
Ethylene propylene diene monomer, or EPDM, is a type of single-ply roofing material ideal for low-slope roofing applications, such as commercial roofing jobs. This material is effective at resisting rain, snow, wind and ultra-violet rays.
EPDM roofing resembles a thin rubber material and is available in large rolls up to 200 ft. long and 50 ft. wide. Most manufacturers offer warranties of five to 30 years, but EPDM may very well outlast the warranty period. Studies have shown EPDM roofing may last 50 years or longer when installed correctly.
What are the advantages of EPDM roofing?
- Low Cost
- Average durability of 40 to 50 years
- Available in white (helps increase reflectivity and control heating/cooling costs)
- Repairs easily
- Pliable: Resistant to varying temperatures and/or building shifts
What's the most cost-effective type of commercial roofing material?
Single-ply is typically the least expensive roofing system due to the relatively low cost of materials and ease of installation.
What’s the most durable type of commercial roofing material?
Commercial metal roofing is among the most durable roofing systems on the market, but metal roofs require at least four-percent slope, according to the National Roofing Contractors Association (NRCA).
For flat roofs, or those with less than a four-percent slope, a built-up roof membrane provides increased durability over most single-ply roofing systems.
What are the pros and cons of an SPF commercial roof?
Spray polyurethane foam (SPF) roofing systems uses a mixture of liquid components that expand 20 to 30 times the original size when applied. SPF roofs offer the advantages of offering exceptional insulation, flexible under varying weather conditions, lightweight, durable and affordable.
The only drawback of an SPF roof is that it needs to be recoated every 10 to 15 years. However, these commercial roofs last for 50 years or longer when properly maintained.
Does commercial flat roofing require a pitch?
No, not necessarily. A pitch, or slope, can be added to a new roof installation to help with drainage, but it isn’t a necessity in most cases.
What are the benefits of commercial asphalt roofing:
- Inexpensive choice taking into consideration installation and maintenance over the life of the roof
- Widely available
- Multi-layer protection against the elements
- Solid track record -- Commercial asphalt roofing systems have been in use for more than 100 years
What does “R-Value” refer to in the commercial roofing industry?
The R-value is simply a measure of how effective a roof is at insulating the building from radiant heat. A higher number is better and can help reduce the cost of cooling a building in the summer.
What are some sustainable roofing options?
Green and sustainable commercial roofing systems abide by the standards developed by the U.S. Green Building Council. Most types of roofing systems offer green alternatives that include one or more of the following:
- Longer than average lifespan (usually 50 or more years)
- High R-value
- Made from recycled materials
- Vegetative roofs (sustainable rooftops consisting of plants)
Commercial roofing systems having the Leadership in Energy and Environmental Design, or LEED, stamp of approval are considered eco-friendly/sustainable options according to the standards developed by the U.S. Green Building Council.
What is a "cool roof"?
A cool roof is one that reflects the sun’s heat rather than absorbing it. This helps reduce the cost of cooling a commercial building and is better for the environment.
The Cool Roof Rating Council (CRRC) determines the overall “coolness” of a roof by measuring its solar reflectance and thermal emittance. Both factors are given a score between 0 and 1 to determine the roof’s overall coolness value. A higher number is better.
What are the benefits of white roofing?
Many businesses are turning to white roofing solutions for multiple reasons. Some of the benefits of white roofing on commercial buildings include:
- Higher reflectivity to help reduce the cost of cooling a building
- Tax incentives offered by some local and state governments for using “cool roofing”
- Lowers the “urban heat island” effect, which causes the temperature in urban areas to be several degrees warmer than rural areas
What is a LEED-certified roof?
The U.S. Green Building Council (USGBC) developed Leadership in Energy and Environment Design, or LEED, in 2000 as a ratings system for builders across the United States. LEED certification means a roof was independently verified to meet standards of energy efficiency, sustainability and environmental health.
How much does a commercial roofing system cost?
The cost of a commercial roof varies depending upon square-footage, type of roofing system and geographic location of the install. For instance, a tar-and-gravel roofing system installed on a 4,000 sqft. commercial building in Florida may cost $20,000 to replace while the same job may be double that in California.
Talk to a commercial roofing contractor to get an accurate estimate. The estimate is typically free, so there’s no risk on your part.
How is the square footage of a commercial roof measured?
Most roofs are measure in squares. Each square is equivalent to 100 square-feet. Create a sketch of the roof and divide into square/rectangular sections to make the calculations easier. Use the area formula (length x width) to determine the square-footage of each section. Once you’ve found the square-footage of each section, add them together to get a total. Divide this total by 100 to determine approximately how many squares of roofing material you’ll need.
What are the top commercial roofing system manufacturers?
Several of the biggest manufacturers of commercial roofing systems include GAF, Duro-Last, Soprema, GenFlex, Carlisle, Versico, Firestone and many more. Talk to your commercial roofer about your options. Choose a contractor with plenty of experience installing the roofing system of your choice.
What causes rubber roofing to swell?
Rubber roofing, particularly EPDM, will swell when exposed to aerosols, refrigerants, and other halogenated and aliphatic solvents. Vegetable oils can also cause swelling of rubber roofing membranes (i.e., kitchen and restaurant applications).
An alternative to EPDM that is far more resistant to solvents, grease and oils is epichlorohydrin, or ECH. It looks similar to EPDM but doesn’t swell when exposed to the aforementioned substances.
Should I be concerned with blisters forming on my flat roofing?
Yes, when rubber roofing blisters it’s a sign that moisture is seeping underneath the membrane. It can lead to severe problems down the line, including major leaks and mold.
Are there building codes I should be concerned with?
There are building codes in place for commercial roofing application you must comply with. These standards are enforced by local and state government agencies to help maintain safety standards and public welfare in commercial buildings. Although building codes vary from state-to-state, many locales have adopted the standards set by all or some of the following organizations:
- International Code Council (ICC)
- National Fire Protection Association (NFPA)
- American Society for Testing and Materials (ASTM)
- FM Global
- Underwriters Laboratories (UL)
- American National Standards Institutes (ANSI)
Your local roofing contractor is the best source for determining your city’s commercial roofing standards and building codes.
What’s the most common cause of commercial flat roofing leaks?
The vast majority of leaks in commercial roofing applications occur at transition areas, such as chimneys, vents, flashing and AC units. A good commercial roofer will take ample time to ensure his/her “flashing detail” is done correctly. A good installation is the key to preventing a leaky roof in the future.
Do commercial roofs require regular maintenance?
Commercial roofing maintenance is a critical part of the maximizing the lifespan of a commercial roof. A regular maintenance plan (i.e., once per year) can help extend the life of the roof by up to 50 percent. Furthermore, it can help prevent leaks and other roof damage. It may even help preserve the roof insulation enough to reuse it the next time you install a new roof, saving you as much as 30 or 40 percent on the new install.
Often times roofing warranties become void when proper maintenance is ignored. Be thorough when reading through the warranty details.
Maintaining a commercial roof isn’t difficult or time consuming. It’s just a matter of keeping the roof clear of tree limbs and fallen debris, excessive snow, pooling water and inspecting the roof for swelling or blisters. If any part of the roof looks “abnormal,” contact your local roofing contractor right away to fix it before it becomes a far more serious problem.
My industrial roof is old and starting to leak, does it need to be completely replaced?
Commercial-industrial roofing systems are designed to last for decades, so even though it may be old and starting leak, doesn’t necessarily mean it requires a complete tear off and replacement. If it’s rubber roofing, such as EPDM, or any other common type of commercial roofing, the fix is often as simple as some patchwork.
Patching up the leaks is far less expensive compared to replacing the entire roof, and it’s an effective strategy for maximizing the life of the roofing system. Your roofing contractor will discuss these options with you, so you can determine whether a patch-up is an option or a complete replacement is in order.