Separated occupancy where separation is not required?

[Otter]

In a proposed VB 2 story above grade building with F-1/B occupancies (non-separated and non-sprinklered), is the building limited to 1 story per Table 504.4? The main floor has half F-1, half B and the second story is B only.

Most examples I see have occupancies where separation is called out in Table 508.4, but where separation is not required by the table do you simply say, “since the F-1 is not actually on the second story, it is allowed”?

2021 IBC and thanks for looking.

 

[Yankee Chronicler]

Non-separated, with an F-1 in the building, the building is limited to one story in height unless the F-1 is a very small percentage of the total building area.

 

[RLGA]

Technically, no, but please read through to the end. If using the the nonseprated occupancies method for the entire building, the most restrictive occupancy applies to the entire building.

You can do a combination of separated and nonseparated occupancies. For example, the nonseparated occupancies method for the first story can be used, and the second story can be separated from the first story with a horizontal assembly.

However, since there is no required separation between Group B and Group F-1 occupancies, use the separated occupancies method, but you are not required to have any fire barriers separating the occupancies per Table 508.4. However, since Group F-1 is limited to one story, it can only be on the first story.

 

[Otter]

Ok, this is making more sense. So the occupancies must be physically separated, but the separation would not need to be fire rated. Maybe put a door at the stairway between the two and keep the F-1 on the main floor and we're good?

 

[RLGA]

Ok, this is making more sense. So the occupancies must be physically separated, but the separation would not need to be fire rated. Maybe put a door at the stairway between the two and keep the F-1 on the main floor and we're good?

They do not have to be physically separated. "Separated" in building code parlance means separated by fire-resistance-rated assemblies, and when used in the context of separated occupancies, it specifically means separated per IBC Table 508.4. Since Table 508.4 does not require fire-resistance-rated construction between some occupancy groups, no fire-resistance-rated assemblies or any type of wall construction are necessary.