Allowable stories

[Sifu]

I have been down this road before, and my thinking has changed more than once. In part, because of discussions here. But now I am facing it again but I can't seem to find the right search phrases to locate our discussions.

Mixed-use strategy/allowable story question: Given a type VB building, 2 story, NS, B and M on the first story, B on the 2nd story. Is this permitted in a non-separated strategy? 2018 IBC.

For arguments sake I used to think no, since a VB, NS, M is limited to one story, then I think I was re-educated to believe that it is allowed as long as the M is not above the single story limit.

I just read and re-read a code corner article by RLGA for the umpteenth time and now I am afraid what I thought I knew is all wrong. Here is the phrase that shakes me from an example provided that is similar:
Since this is a 2-story building, all construction types limited to 1 story are not allowed.

For the record, I often marvel at how few people understand this. I should be more careful because sometimes I apparently don't completely understand it.

 

[Sifu]

I think I found what I remembered the most, now I just have to make sure I understand it again. I think the conclusion for my situation would be that the M on the first floor is permitted in a two-story building, but if the B above is not separated it would be part of the M below and would then violate the 1 story restriction for the M occupancy. So as non-separated the M would not be required to separated from the B adjacent to it on the first floor, but would be required to be separated from the story above due to story limits. And, if they used a separated strategy since no separation is required from the M to the B, no separation would be required on the first floor between the M & B, but the horizontal separation would still be required?

Mixed use Multi story building and Non-separated Occupancies

First post, thank you for your input. I am having a difficult time reconciling the provisions between IBC 2018 508.3 Non-separated Occupancies and 506.2.4, Mixed Occupancy, multi-story buildings. Most of what I am seeing is that if the Non-separated provisions are to be used, the most...

www.thebuildingcodeforum.com

 

[Paul Sweet]

I go by IBC 508.3.2 for non-separated mixed use:

"The allowable building area, height and number of stories of the building or portion thereof shall be based on the most restrictive allowances for the occupancy groups under consideration for the type of construction of the building in accordance with Section 503.1." (underline added)

 

[Sifu]

So you would not permit the M occupancy in this building at all?

 

[princeofpen]

You would have to do separated mixed use with "B" only on 2nd floor as "M" isn't allowable on 2nd

 

[Paul Sweet]

You can keep the M on the first floor if you either (1) sprinkle the building, (2) make it protected (VA) construction, or (3)separate the uses.

 

[Sifu]

This came to me as a problem child from an AHJ that had already reviewed the plans. There is, of course, more to the story, and I simplified the scenario to aid in comprehension. It came to me with a lot of problems, somewhat unrelated to my question. In digging deeper I found that they were putting an M under a B with no separation but before I went down that road (not the road they were traveling on) I figured I better verify my understanding.

Unfortunately the DP made no mention of the mixed-use strategy, tried to call the F2 an S2 but provided a 2-hr vertical separation to the M. This thing made it through plan review that way, but then they modified the previously mentioned S2 and only then did the plans examiner raise a red flag about it being an F2. Now they are upset because they think they thought the F2 classification would be a problem. Their description of the activity in the scope of work would/should have made this an F2 from day one.

The question posed to me was (paraphrased) "is there anything that would require sprinklers or additional separations if re-classifying the S2 to an F2?" to which I answered nope, the 2-hr vertical separation is good for both F2 and S2 to the M, but the M in a 2-story is a problem, so horizontal separation is required, regardless of whether it is an F2 or an S2 beside it. The initial plan review did not catch this, and it only came to their attention once they were called out on the re-classification, but the problem isn't really with the re-classification. Not sure what the BO will do with this now.