Garage/house fire door

[Marcel R. Cyr]

It is common for a fire door to have a fire protection rating lower than the wall fire resistance rating in which it is installed.

This is justified in part by the fact that, under normal conditions of use, the potential fire exposure in the vicinity of a door opening is decreased, since there will usually be a clear space on both sides of the opening for traffic purposes. Since wall assemblies are put together at the site, their uniformity is not as certain as a fire door assembly that is factory assembled.

One-third-hour or 20 minute doors are used in one-hour-walls. These doors are used for corridor applications and in other applications where smoke and draft control is a primary concern.

Changing a door rating unnecessarily to a one hour rating will also reduce the size of the glazing area as permitted by the manufacturer of the door.

Although a typical wall in a residential separation between the house and garage is called a 1 hour wall, it is in fact only rated for 45 min. as an assembly. Therefore a 20 minute door is more than adequate.

You can see this assembly here: http://literature.usg.com/pdf/SA924.pdf


Just my two cents.

Marcel

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