Fire Ratings and What They Mean

Date:Feb 11, 2019

Fire rated doors are an important part of a building’s fire control system. These include exit doors, corridor doors, and any other protected openings within your building like access doors, roof hatches, or floor hatches. When access doors are closed, they should block gas, smoke and extreme heat from flowing through.

Meeting fire safety codes mean different things in different buildings and locations. To make sure your access doors are safe and legal, learn more about the codes, parts, and construction details that determine their fire ratings.

NFPA Standards

Each access door comes with its own fire door label, which tells you how it was constructed or tested, how and where it should be installed, and how it will improve your building's safety. The following National Fire Protection Association(NFPA) standards apply to different levels and types of fire protection:


Classified as the official "standard for fire doors and other opening protectives", this safety rating applies to the installation and maintenance of swinging, sliding, rolling and hoistway doors, as well as any fire doors, access doors, chute doors, or fire exit windows that allow people to exit or enter your building. NFPA 80 regulates these openings to make sure your building can prevent or slow down the spread of fire and smoke, at least until occupants have exited safely.

NFPA 105

This installation standard applies to smoke door assemblies in particular. Unlike fire doors, smoke doors are primarily built to stop the flow of smoke. The NFPA enforces this code to prevent people from inhaling too much smoke, but doors and other openings that meet this standard will also help protect your property from smoke damage.

NFPA 252

You're responsible for making sure your building meets the NFPA's fire and smoke requirements. However, NFPA 252 is up to the manufacturers and laboratories that actually test your doors and determine their ratings. This standard is enforced to make sure door openings can regulate the spread of fire. "Fire" technically includes the flames themselves, the rise of indoor temperatures, and the presence of hot gases.

Parts that Matter

In order to meet NFPA standards, manufacturers and construction teams must pay attention to each of the following parts:

Door Glaze

Plain paint isn't usually fireproof, so access doors must be coated in fire-rated glaze. Different doors and buildings have different glaze requirements. For example, most interior doors may not have more than 100 square inches of glaze.

Glass Inserts

The NFPA's standards for smoke and fire doors also apply to the glass inside them. Any windows or glass inserts should meet testing requirements for shattering, cracking, and transmitting heat or gases.

Door Frame

Door frames often have their own labels, which tell you their specific fire-resistance ratings. If a frame's label is higher than the door's rating, it will resist fire or heat for a longer period of time. However, the overall door assembly rating is always the lowest of these two numbers.


It's important to inspect and maintain seals regularly, especially on exterior doors. Also make sure that your product is tested for weather, fire, and moisture considerations.

Other Factors to Consider

Of course, your building's fire safety isn't completely limited to the doors and door frames that enable occupants to exit safely. Stairways and other interior passageways also need to stay cool for a certain amount of time, and sprinklers decrease the heat and speed at which a fire spreads. As a result, your commercial doors' fire rating requirements may depend on your other construction decisions.

For example, according to the International Building Code (IBC), exit door assemblies must have a maximum transmitted temperature rise of 450° F. However, you don't need a temperature-rise door if your commercial building has an automatic sprinkler system — as long as that system covers the entirety of your interior floor space and passageways. All requirements also depend on your fire-resistive walls and ceilings.

Fire Rated Access Doors

At Williams Brothers, our entire fire-rated inventory meets or exceed the requirements of both NFPA 80 and NFP 252. We offer uninsulated, insulated, heavy duty, and standard access doors that withstand between 30 minutes and three hours of extreme heat and fire.

Of course, a fire-resistant door can't perform its life-saving duties without an air-tight, fireproof seal, and this depends on the quality of its edging and insulation. Our gasketing and insulation options include fire-tested Hot Smoke Seal™, closed cell sponge stripping, Thermafiber® noncombustible felt, and foam insulation boards with code-compliant resistance ratings.

Prevention is your best defense against devastating threats to your building, but you should still be prepared for anything. Contact us today to learn more about our fire rated access doors and other safety and security products.

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