6 Most Common Types of Commercial Roof

There are myriad decisions you as a business owner must make. When to do something yourself, when to call an expert, how to price your products and services, how to balance family and work responsibilities, what to choose for a commercial roof, and what to do when your roof needs repair. 

Whether you’re looking for a new commercial roof, needing to repair the roof you have, or just want to be prepared for the maintenance needed down the road, it helps to have an overview of common commercial roofs and roofing materials.

Built-Up Roofing (BUR) Membrane

Built-up Roofing Membrane has been around for more than a hundred years. These BUR roofing systems are often commonly referred to as “tar and gravel” roofs. It is made by alternating bitumen with reinforcing fabric. It’s called built up because it usually includes multiple layers, as opposed to a single-ply roof. 

Pros

  • A well-built BUR Membrane roof can last 30 years.
  • BUR offers excellent protection against water, UV rays, and inclement weather.
  • It costs little to maintain compared to other roofing systems.
  • Initial cost to install or repair is around $4 per square foot.

Cons

  • Finding the source of a leak can be difficult and sometimes requires dismantling the whole roof.
  • Built-up roofing is not flexible in cold temperatures. This makes it susceptible to damage.

Repairs

Repairing one of these roofs is an involved process. The hardest part is finding the source of the leak. 

Metal Roofing

Metal roofing systems are made from metal sheets, pieces, or tiles. These roofing systems are characterized by high resistance, impermeability, and longevity. Corrugated galvanized steel is a common material in metal roofing. For commercial roofs, zinc, aluminum, copper, and steel alloys are also used. Some metal roofs, especially commercial roofs, have various coatings for anti-rust and UV protection. 

Pros

  • They are recyclable, a pro for most business owners and the people they serve.
  • They last 30 to 75 years, depending on the material, installation, and maintenance
  • They are typically lower maintenance than BUR roofing systems.
  • They are energy efficient.

Cons

  • They are higher up- front cost to install or replace ($10 to $18 per square foot).
  • Severe hail can ruin metal roofing.

Repairs

Repairing a metal roof is complex and requires a professional.

Modified Bitumen Commercial Roofing

Modified bitumen roofing (MBR) is a lighter-weight alternative to BUR and was developed in the 1960s. It’s cleaner to handle and install than traditional BUR. Most people consider it a great alternative on both residential and commercial roofs. 

Picture rolled sheets that are three feet wide made up of an asphalt-based material with a mineral top coating. Now picture these massive sheets to be up to 36 feet long. After a base sheet membrane is layed on the roof, these sheets are simply rolled out onto the membrane and roof.

There are two methods of adhering the sheets to the membrane of the roof. One is called torch-down and involves heating the side of the sheet that will touch the roof. The other is a peel-and-stick kind of operation.

Pros

  • MBR is a simpler and cleaner process to install than BUR.
  • Offers better elasticity and flexibility at low temperatures (compared to BUR).

Cons

  • Some application techniques require an open flame/torch, which carries safety risks.
  • If the overlapping joints are not correctly adhered at installation, they can leak.
  • Modified bitumen is generally considered less attractive than other roofs, like BUR or membrane roofs. 

Repairs

The biggest issue with repairing modified bitumen roofing is determining how much, if any, moisture has made its way to the asphalt layer. If this process is avoided, you could patch right over and trap moisture.

Thermoset (EPDM) Commercial Roof Membrane

EPDM roof membranes are a lot like what they sound like: a lining type roof material also used for fish pond lining. EPDM is made of heavy-duty rubber that stands up to the elements. It can be fastened to the roof in various ways, including glue and metal fasteners.

Pros

  • Repairs are relatively simple and inexpensive.
  • The roof deck doesn’t need reinforcement because EPDM roofing is lightweight.
  • EPDM roofing can retain heat to lower heating bills in the winter.

Cons

  • Though durable, EPDM is not as durable as other types of roofs that are not as easily punctured with foot traffic or falling tree branches.

Repairs

The seams between membrane sheets are common areas for leaks, even though they are sealed. Though some sources say repair can be inexpensive and done by building owners, extensive repairs are best done by a professional.

Thermoplastic (PVC & TPO) Roof Membrane

Thermoplastic roofing membranes are made from a durable material with a high-temperature tolerance, and are among the fastest growing in the industry. PVC and TPO roof membranes are the most common types of thermoplastic roof membranes.

Pros

  • Lower cost than some roofing options.
  • Heat-resistant and energy efficient.
  • Can withstand heavy rain or hail, wind, or debris.
  • Due to their durability, they are often the option of choice in hurricane zones.

Cons

  • Quality variations: there is a great amount of quality variation on the market for thermoplastic roof membranes.
  • Seams: Like with other roofing systems, seams can be problem areas on membranes and are usually the first places building owners will have problems with leaks.
  • Lamination: laminated materials are prone to cracks.
  • Newness: Thermoplastic roofing systems have not been around that long. Therefore, most longevity statements are estimates.

Repairs

Repairs for thermoplastic roofing systems are similar to other membrane roofing systems.

Garden “Green” Roofing System

A garden or green roofing system is a roof with vegetation. It’s also called a garden rooftop. It can be created on any waterproof membrane. 

When the city of Roanoke, Va., installed a green roof on its municipal building — at the cost of $123,000 — it added 20 to 60 years to the life of the current roof. (Roanek.gov)

Pros

  • Sustainability. Their name is a giveaway—green roofing systems are good for the planet.
  • Commercial value. Sustainability becomes a greater and greater factor to residential and commercial buyers alike.
  • Aesthetic. Garden green roofing systems are beautiful.
  • Energy-saving. A green shady roof will often only get up to 77 degrees on a hot day, versus 158 on the same day with an exposed roof.

Cons

  • While more of a consideration, it’s difficult to get water to some green roofs. Without irrigation, you land with taking watering cans up to your roof repeatedly.
  • Also consider how you will access your rooftop garden

Repairs

However you repair the membrane under your garden is how you repair a green roof. Vegetation is removed and repairs are made.  

Roof Choice Summary

You have three options when faced with leaking or damaged commercial roof systems—replace, delay, or repair. 

Replacing a commercial roof is a sizable investment and can eat away at your business overhead costs. Repairing or delaying, however, can feel like trying to avoid the inevitable. 

If neither replacing nor repairing your roof is attractive to you but you need to remedy immediate damage, consider the best of both worlds—a North Star Roofing restoration.

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