Ask The Expert Q&A: What To Ask About Fire Ratings and Codes When Re-roofing

Commercial roofing systems must meet or exceed building codes and insurance requirements. Sometimes roofing assemblies are part of the fire-rated assembly for the building, and sometimes they’re not. So when it’s time to re-roof your property, your roofing contractor needs to fully understand the role your current roof plays in fire safety and how to install a new roof that maintains or improves it.

Joseph Cannon offers details:  

Q: What are the different fire ratings for roof assemblies?

A: Fire-rated roof assemblies have been tested for their fire-containment capabilities. The rating classifies how well an assembly is able to confine and isolate fire during tests. There are four classifications of fire ratings for roofing assemblies: Class A, Class B, Class C, or Unrated. Class A is the most stringent and Class C provides only light protection against fire. Materials that don’t meet Class C rating requirements are classified as unrated. Testing is performed by third-party labs, with UL being one of the most well-known. It offers advice for achieving code compliance for Class A, B, and C Roof Ratings.

Q: What are the different ways a roof assembly can be part of the building’s fire-rated assembly?

fire-rated construction

Fire-rated construction follows precise specifications. Here are two examples of fire-rated construction for steel-framed roofs decks (USG Fire-Resistant Assemblies Catalog).

A: There has to be a firebreak somewhere in the roofing assembly. For example, insulation can be sprayed on the roof deck, the assembly can include fire-rated sheetrock, or a sprinkler system can be installed in the building. The key is knowing which roof assembly components are actually part of the fire-rated assembly. If a roofing contractor demos the existing roofing assembly, it’s possible to also demo the firebreak which will then need to be replaced during re-roofing. The image to the right is from the USG Fire-Resistant Assemblies Catalog and gives just two examples of fire-rated construction.

Q: How can I ensure a fire-rated assembly will remain intact when re-roofing?

A: Use a reputable contractor — choose one with a good client list or one that does high-profile jobs. Less-experienced roofers may be unaware that your roofing system is part of a fire-rated assembly that affects whether the building meets code or not. Also, some contractors may be aware of fire rating issues but not care, or say they’ll do whatever you want them to or that you’re the boss and not the codes. These are not the people you want working on your property. A good way to determine if your contractor is experienced is to call the county permitting office and ask if they’ve pulled re-roofing permits lately. The permitting office logs the permits for building inspectors and they are part of the public record.

Q: Are there materials to avoid when re-roofing because of fire safety issues?

A: Almost every component of a roofing system can relate to fire safety. From the materials used in constructing the roof deck to the insulation to the roof covering and adhesives, each item has a level of fire resistance. A metal roof deck, for example, is more fire resistant than a plywood deck. UL maintains lists of products that have been evaluated for each rating in a searchable database — a very good place to start.

Again, if you use a reputable roofing contractor you can be confident they’ll use materials that meet the correct fire rating and install them properly. If you don’t use a reputable contractor, you really can’t be sure. For example, when the price of ISO was very high in the 1990s a lot of contractors saved money by using insulation that was highly flammable — it was basically the same material as a styrofoam cooler. If your roof was installed during this time, have your roof evaluated to make sure that material isn’t part of your roofing system. Your property could also be at risk if you have a roofing system that was installed over an existing EPDM membrane. EPDM that is encapsulated between two layers of insulation is flammable.

Q: I don’t want to spend a lot of money on my roof but I still want to be in compliance. Can I choose a roof assembly with a lower rating to save money?

low slope fired ratings

Low-slope roofs and steep-sloped roofs have different construction standards to meet when it comes to fire safety. The fire-rating of each component comes into play.


A: Roof ratings are not interchangeable. Different buildings must meet different ratings — it depends on the type of building and its location. Warehouses have a different fire rating than hospitals, for example. Also, some municipalities will increase their minimum fire classification requirements if they’ve had a lot of fires. The requirements for your property will be based on minimum requirements determined by your jurisdiction. Price doesn’t factor in. The fire rating system is there to protect you and the occupants of your property.

Q: My property has a steep slope roof — are fire code considerations different for me?

steep slope for fire rating

Many properties have a combination of low-slope and steep-slope roofs within the same roofing system, which can lead to a more complex set of processes when re-roofing.

Yes, for “most” steep slope roofs the fire break is a ceiling level although occasionally it’s at the roof level. Still, you need to make sure the roofing system has been constructed properly and the attic has the appropriate sprinkler system. When people live in a building, steep-slope roofs are a good choice for fire safety reasons, especially for nursing homes and similar facilities. A good roofing contractor can advise you on any changes you might need to make.

Q: What kind of liability could I face if I circumvent the fire code?

A: No one wants to think about things like this but the truth is you could face criminal prosecution for your roof does not meet fire codes — the codes are there for a reason. Both the owner and roofer can be liable for any damages. In the end, the building will need to be brought up to code anyway.

Sentry Roof Services walks away from projects with specs that aren’t up to code regardless of legal liability. Cutting corners on safety is not something we do.

When it’s time to re-roof, working with professionals who have a deep understanding of fire-rated assemblies and materials is your best bet. It can also be a good idea to hire a consultant if you’re concerned about the facts, have complex issues with your roof, or want a third-party opinion or oversight. Consultants can also write a scope of work so the bids you get for your re-roofing project are for the same exact project. A consultant can also observe the work as it’s completed to make sure your fire-rated assembly is installed according to plan.

If you’re interested in learning more about codes and fire safety, the National Fire Protection Association (NFPA) makes code-related publications available to the public, including the NFPA 5000, Building and Construction Safety Code. Many previous publications have been rolled up into this single publication, and the 2018 edition includes a new section on fire and structural design parameters for roof-mounted PV (photovoltaic) panels. If you have any other questions about fire-rated assemblies, fire classifications or the re-roofing process, I invite you to give me a call.

Photo credit for main photo: William Murphy

Joseph CannonJoseph Cannon is Vice President of Estimating and Chief Estimator for Sentry Roof Services. He is responsible for bidding all new construction work and re-roofing projects. He has over 15 years experience in the roofing industry and works with single-plys, metal, shingles, and many other commercial roofing products.  

To contact Joseph, you can call his direct line at (678) 301-5570.

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