Fire Door Protection Ratings May Be Less Than the Rating For the Wall Assembly
There is a common assumption that a wall with a certain fire rating will require a door with an equal rating. While the door will generally need to be rated it oftentimes requires a lower rating. These are the numbers from the 2006 International Building Code.
First, exterior walls always allow reduced ratings in doors. Both 3 hour walls and 2 hour walls require a 90 minute door. A 1 hour exterior wall requires a 45 minute door.
Where you have a fire barrier with a 1 hour rating at a shaft, exit enclosure or exit passageway you will need a 1 hour door. For other fire barriers it is reduced to a 45 minute door.
Where you have a fire barrier with required rating over 1 hour the need for reduction varies. Both a 4 hour wall and a 3 hour wall require a 3 hour door. Both a 2 hour wall and a 90 minute wall require a 90 minute door. In the 3 hour wall they will allow you to use a pair of 90 minute doors, but only in that once instance.
A 1 hour smoke barrier requires a 20 minute door.
Fire partitions that are corridor walls allow reductions. For either a 1 hour wall or a 30 minute wall you'll need a 20 minute door. With any other fire partitions a 1 hour wall requires a 45 minute door and a 30 minute wall needs a 20 minute door.
In summary, it is actually a very confusing chart, so feel free to check back when you are putting together your door schedule.
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Tagged as: Building Code, doors, fire rating