Incidental Use Areas, IBC 508.2

Given: An office building, B occupancy, includes storage spaces that are greater than 100 square feet.

Question: If the building is analyzed as a mixed-occupancy (either separated or non-separated per 508.3.2 or 508.3.3 of the 2006 IBC) do the provisions of Section 508.2 (incidental uses) still apply? Or does this section only apply when the building is analyzed as a single occupancy?
Original Post
If the building is classified as a single occupancy, the storage area would be required to be separated from the remainder of the building by a 1-hour fire resistance rated fire barrier or provide an automatic fire extinguishing system

If the building is classified as Mixed Occupancy, then the storage area is not required to have a 1-hour fire barrier.

SH Cool
Great question.

First, an office space (Group B) allows for the storage of office supplies and files without having to classify those areas as Group S. So that question is moot.

Secondly, your question about incidental uses stirs up a lot more concerns. When teh initila IBC was drafted, I wrote a ton of challenges to teh incidenatl use table beacuse I had real concerns that sprinklers were considered to be a panacea for everything. When half of those challenges were approved I shouold have been satisfied - but, I wasn't beacuse the most important uses were ignored by teh "committee".

Your question caused me to look at teh table and sections more closely. The basic intent for this table was to cite uses that needed passive protection regardless of teh main use. Many of these uses came from teh UBC and we were OK with them. But, some of teh described uses make no sense.

For example, how is it that a parking garage is incidental. It is usually a major aprt of any mixed use. In reviewing teh separations required, Table 508.3.3 does not require a rated separation between an S-2 and an assembly use in a sprinklered building. If you use Table 508.2 then you might say that it requires a one-hour separation. But, if you use Section 508.3.2, then no separation is required at all.

Analysis: teh parking garage is not incidenatl and no separation is required if it can comply as a non-separted use. But, is that the intent of teh Code?

The previous UBC gave us more distinct direction on how to address these uses. It's unfortunate that teh IBC does not. I do beleive that most designers will provide at least a one-hour separtion for parking garages with protected openings.

I'm open to more duscussion. (please forgive my typing - I got big fingers)

Chuck daleo
Here is an interesting piece of information for you. In the 2009 IBC, Table 508.2.5 "Incidental Accessory Occupancies", no longer has "Storage Rooms" listed as an Incidental Accessory Occupancy Big Grin

There is a "Waste and linen collection rooms over 100 sf" entry, but not "Storage Rooms" as we had in the 2006 IBC.
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