Residential Wood Fire Door Requirements

Fire-Rated Wood Doors

• These doors are made of wood, such as lumber or plywood, that has been treated with chemicals so as to cut down on its tendency to spread flames. This treatment helps reduce the amount of flammable volatile substances that the wood releases on exposure to fire. The treatment also helps cut down on the effective heat of combustion of the wood. This sort of treatment helps stop the spread of flames, especially in the initial stages of the fire.

Rating

• Ratings of fire-rated doors are based on how long they can withstand a fire. For instance, some doors can withstand a fire for 90 minutes, some for 60 minutes and some for 45 minutes. The maximum such rating is for 180 minutes. These 3-hour rated doors are used in walls that separate buildings or in walls that subdivide a large building into smaller areas. Doors with a 20-minute rating mainly find use in corridors in order to cut down on smoke and draft.

Code

• A wood fire-rated door, its hardware and its assembly structure should all conform to local code. As well, many localities specify that these doors be tested by a suitable authority before being eligible for sale in their locality. Underwriters Laboratory and Warnock Hersey are two such testing agencies. There are also standards from other agencies such as the National Fire Protection Association, the Uniform Building Code, the International Building Code and the American Society for Testing and Materials.

Testing

• Testing of these doors is done to replicate real-world fire conditions. In positive-pressure testing, testers place the door assembly in a furnace exposing it to temperatures of up to 1,800 degrees Fahrenheit. A 20-minute rated door is tested thus for 20-minutes, for instance. During this time, the door should not develop any cracks or allow any fire through to the other side of the door. After half of its rating time, or 10 minutes in the case of a 20-minute door, the door is also subjected to a stream of water from a fire hose.