Storage under NON egress stairs - rating required?

[PatrickGSR94]

Is there any case in which storage can be underneath stairs, and not need to be rated? Some of my colleagues are convinced there are, like if the stair is solely for maintenance access, and not for egress, i.e. stairs to an equipment platform. Not required to be enclosed (the stairs themselves). So does the space below the stairs still need to be rated if intended for storage? My thoughts are that a rating WOULD be required.

 

[Penguin87]

Equipment platform stairs are typically not rated - they are defined as not part of the building structure, and are not occupied space.
I have never seen one fire rated at all.

Look at section 505.3

Question would then be, "what kind of storage?"
And the rest would likely be up to your building official.

 

[PatrickGSR94]

Equipment platform stairs are typically not rated - they are defined as not part of the building structure, and are not occupied space.
I have never seen one fire rated at all.

Look at section 505.3

Question would then be, "what kind of storage?"
And the rest would likely be up to your building official.

Well in this case we're talking about a wood-framed single-story structure, with roof trusses (R-4 occupancy, group home built to commercial construction standards). The trusses have an equipment area built in for HVAC and water heater, with permanent stairs going up there. No storage up there on the platform, and it's not an egress stair. So while the stairs ARE enclosed (or, at least separated from conditioned space), it's technically not required to be. But then there's this framed in area under the stairs, which could be used for general storage. And the question is, does that area have to be rated, with 5/8" drywall, fire caulk, rated door and frame with closer, and so forth.

 

[mtlogcabin]

You have a penetration between a required fire resistance assembly. There are exceptions in 708.4 that I suggest you review and determine if they can be applied to your project that may not require the fire rated roof ceiling assembly.

"But then there's this framed in area under the stairs, which could be used for general storage."

You need sprinkler coverage under the stairs and if it is enclosed storage you will need to include a sprinkler head in that room.

420.2 Separation walls.
Walls separating dwelling units in the same building, walls separating sleeping units in the same building and walls separating dwelling or sleeping units from other occupancies contiguous to them in the same building shall be constructed as fire partitions in accordance with Section 708.

708.4 Continuity.
Fire partitions shall extend from the top of the foundation or floor/ceiling assembly below and be securely attached to one of the following:

1. The underside of the floor or roof sheathing, deck or slab above.

2. The underside of a floor/ceiling or roof/ceiling assembly having a fire-resistance rating that is not less than the fire-resistance rating of the fire partition.

 

[Penguin87]

Well in this case we're talking about a wood-framed single-story structure, with roof trusses (R-4 occupancy, group home built to commercial construction standards). The trusses have an equipment area built in for HVAC and water heater, with permanent stairs going up there. No storage up there on the platform, and it's not an egress stair. So while the stairs ARE enclosed (or, at least separated from conditioned space), it's technically not required to be. But then there's this framed in area under the stairs, which could be used for general storage. And the question is, does that area have to be rated, with 5/8" drywall, fire caulk, rated door and frame with closer, and so forth.

That is a very different scenario, and would require looking at detailed plans and probably a site visit to determine. That almost sounds like a mezzanine or a second floor but I don't have a good mental picture of the construction.

The continuity of the fire assemblies probably needs to be verified.

 

[Yankee Chronicler]

Wood-framed, single story, roof trusses. Type V-B construction?

Mechanical space in the trussed attic. No requirement for the roof-ceiling assembly to be rated. Stair to the mechanical space within the trusses not rated and doesn't have to be rated.

I don't see anything in the code to disallow storage in the space beneath the stair, and I don't see anything requiring a fire separation from the stair.