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How Fire Rated Hollow Metal Doors are Tested

Hollow Metal Doors are an important part of the security and the fire resistance of a commercial building. These doors are often used as outside fire escape exits, unlike aluminum glass entrance doors.

These doors undergo specific testing to meet UL standards due to heavy-duty use and fire resistance requirements.

These strict guidelines ensure that hollow metal fire rated doors have the correct fire protection rating to keep the occupants of a building safe in the event of disaster.

Materials Used for the Metal Doors

When talking about frames and hollow metal doors, it is important to know there are different materials used to make these doors that could impact their fire resistance. Cold rolled, hot rolled, galvannealed, galvanized, and stainless steel materials are  all often used and tested based on the UL safety standards.

The standards these doors meet will determine the level of fire safety protection, in terms of rating, the doors will receive on their label.

Are All Steel Doors Fire Rated?

Yes, a "rated" steel door meets local code standards, but you must understand the tests used and match capabilities with local regulations.

Doors undergo rigorous fire and closing device testing, varying in design and performance levels for frames and assemblies.

Installers must grasp fire resistance, properly assembling and installing metal doors to meet local fire code criteria.

Building codes are specific to cities, states, even countries and therefore it is important to follow your local code guidelines for the type of building and the associated codes it must meet.


For example, the requirements for what type of hollow metal door used is often based on the use of a building, and how many people will occupy it at a given time.

A doors fire rating is based on time the door resists heat & flame.

Door fire ratings are based on time. The rating depends on how long the assembly and door can withstand flame exposure during a fire. The test examines the hardware, the wall, and the full hollow metal door assembly as per building code standards.

They use a large furnace to test the door against its specified rating. The door and wall enter a gas furnace with high-temperature flames. We monitor them for integrity and flame spread. The door heats up to test its fire rating against intense flames.

In this process, they also test other parts of the door using standards like ANSI/UL10 and UBS 7-2 to evaluate the cotton or foam padding.

Will the pad crack, will there be openings, or seams in which hot gases will be able to escape in the first half hour of the test?

Once the testing completes, workers remove the door assembly and subject it to additional tests, including impact, cooling, and erosion.

After cooling, doors rated over 20 minutes undergo a hose stream test with specific water pressure. During this water test, the stream cannot dislodge any glass over more than 5% of the door surface area.

People often use wire glass in fire doors to prevent glass breakage. Additionally, they must ensure no cracking, separation, or other damage occurs, like openings between the wall and door

Available Rating Labels

After testing, the doors receive one of five UL fire ratings: 3-hour, 90-minute, 60-minute, 45-minute, or 20-minute.

Door manufacturers must meet UL criteria and often join organizations like the Steel Door Institute. Testing is done by independent labs.

When CDF Distributors receives hollow metal doors, they are already UL certified for 3 hours, labeled with plastic.

Often though, local codes require that the steel door match a specific rating, thus as a UL certified labeling facility, CDF will apply the proper UL fire rating label upon customer request.





June 25, 2015
Wayne Foreman

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