Fire Rated Doors and Frames
We are a UL certified fire label shop and can label our hollow metal doors and frames with up to 3 hour fire ratings. We keep 18 gauge hollow metal doors in stock with 16 and 14 gauge hollow metal frames. Fire rated wood doors are ordered in as needed.
There are some basic requirements for an opening before it can be classified as fire rated:
The wall, frame, and door all have to be fire rated. This is self explanatory as it would not make much sense to put a labeled door in a non rated wall just as you can't put a non labeled door in a rated wall and call the opening fire rated. The purpose of a fire rated opening is to retard fire for a specific period of time (see below for different ratings) so all components of the opening will have to be rated.
The door must be self closing. If the door is left open during a fire, then that opening cannot retard the fire as it was meant to do, so the door has to close after somebody passes through it. This is usually done by a door closer or, in some cases, spring hinges. Both serve the same purpose in that the door will close and serve its purpose of holding back the fire.
The door must be self latching. Push and pull plates cannot be used on a fire rated door. The door has to latch into the frame when closed so it stays shut until it is manually opened. This prevents the door from opening during a fire if something falls against it. This means that you have to use at least a passage set on the door.
Steel ball bearing hinges must be used. Brass, bronze and other bases cannot be used. The hinges must have a steel base on fire rated doors. Plain bearing hinges cannot be used as well. Ball bearing hinges ensure the door will not come loose from the frame and fall out of the opening.
As stated above, the purpose of a fire rated opening is to retard fire for a specific period of time. Most labeled doors will have an A, B, or C label:
A label: 3 hour rating (for a 4 hour wall). These doors are used for openings in walls separating buildings that are joined together. No glass is allowed in these doors.
B label: 1 1/2 hour rating (for a 2 hour wall). These doors are usually used for stairwell doors but are sometimes used at all the rated walls in a building. 100 square inches of exposed glass is allowed.
C label: 3/4 hour rating (for a 1 hour wall). These doors are used for openings from a corridor into another room in the same building. 1296 square inches of exposed glass is allowed.
Louvers can be installed on fire rated doors but they have to be fusible link. This means that once the heat from the fire reaches a certain temperature (usually 105 degrees), the fusible link will melt which causes the louver blades to close . This will help prevent the spread of fire. The maximum size for these louvers is 24 x 24. There is no glass allowed in a fire rated door if it has a louver and no louvers at all can be installed in a 3 hour rated door.
Stairwell doors have to be fire rated but they will also have to be rated as the temperature rise type if the building is 4 stories or higher. This means that the temperature on the stairwell side of the door can't get over a certain amount (usually 250 or 450 degrees) during the first 30 minutes of a fire. This is due to the fact that people are racing down the stairs in a panic during a fire and the ones up front are getting pushed into the door and crushed up against it...rather than being able to actually open the door and leave the building...from the people behind them panicking trying to get out first. The people up front were getting burned by being pressed against the hot door due to a fire on the other side of it.
Remember to follow the requirements listed above. Specific codes differ from area to area but these are the standard.