Fire rating for structural members in IIB construction

[tuzi]

I am referencing the 2021 IBC as adopted in Maryland. In Type IIB construction, primary structural members such as columns and beams are not required to be fire-resistance rated per Table 601, unless another code provision—such as proximity to property lines, occupancy separations, or specific use conditions—requires otherwise.
Did I interpret correctly?

Thanks,

 

[walker.t]

unless another code provision—such as proximity to property lines, occupancy separations, or specific use conditions—requires otherwise.
Did I interpret correctly?

Yes, you interpreted Table 601 Fire-Resistance Rating Requirements for Building Element correctly.

such as proximity to property lines, occupancy separations, or specific use conditions—requires otherwise.

Yes, any other code provisions would apply. But in the case of rating structural elements…

1. Proximity to property lines affects the rating and amount of openings in exterior walls, it doesn’t affect the rating of elements inside the building envelope.
2. Per IBC 508.4.4.1, occupancy separations per Table 508.4 are the ratings required for the fire barrier or horizontal assembly used for the separation - you don’t have to rate the structural frame, but if something happens to fall within a fire barrier it will also happen to be protected by the fire barrier.
3. Regarding special use conditions, I can’t think of anything off the top of my head that requires rating of structural elements in Chapter 4, wouldn’t hurt to check to see if something applies.

as adopted in Maryland

Sorry, I can’t speak to any specific changes Maryland may have made.

 

[steveray]

Correct...non-fire rated, but non-combustible....

 

[walker.t]

unless another code provision

any other code provisions would apply

Should have though to mention this when I mentioned fire barriers, but a good example of a code provision that would require rating part of the structural frame would be the requirement for rating supporting construction for fire barriers per IBC 707.5.1.

Here’s a recent post that talks about supporting construction:

Post in thread 'Stair separation & continuity of fire barriers around primary and secondary members'

Friday at 1:12 PM

The floors at offsets also need to be 2 hour rated, so any walls, beams, and other structural members outside the stair enclosure that support the other end of this floor framing also require a 2 hour rating. This can get incredibly complicated, especially if the building official will not permit any breaks in the fire-rated gypsum board.

• Paul Sweet

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