IBC 'Nonseparated Occupancies' and NFPA 101 'Mixed Occupancies'

[dmoreholt]

Hi All,

Long time viewer, first time poster. I'm working on a small commercial project and running into a disagreement with the Fire Marshall regarding required Fire Separations in a multiple occupancy building. I mostly do residential work so appreciate everyone's experience on this.

From what I can tell, there is a contradiction between the IBC and NFPA regarding rules for nonseparated multiple occupancy buildings. IBC 2018 508.3 'Nonseparated Occupancies' provides some leeway for buildings with multiple occupancies. It states that you can have a building with multiple unseparated occupancies as long as you apply code requirements for each space per the occupancy classification of the space and that the most restrictive provisions of Chapter 9 (Fire Protection and Life Safety) for each occupancy apply to the whole building. Some high hazard occupancies and Residential separation requirements still apply. This makes a lot of sense to me. There are many small buildings with multiple occupancy types where the small size of the building negate any realistic dangers to life safety from having these occupancies next to each other without separation.

NFPA 101 2021 (applicable code on the project) seems to have a similar section but upon detailed reading (And my FM's interpretation) it appears to be much more restrictive in a way that (to me) does not make sense. Section 6.1.14 provides for 'Multiple Occupancies'. It categorizes 'Multiple Occupancies' as either being 'Mixed Occupancies' or 'Separated Occupancies' and also includes provisions for incidental occupancies (appears to be similar to 'Accessory Occupancies' in the IBC). Per section 6.1.14.3 'Mixed Occupancies' appear to be similar to 'Nonseparated Occupancies' in the IBC as it includes the requirement for the most restrictive requirements of each occupancy to apply for the whole building. However, in section 6.1.14.1.2 it states that "Where exit access from an occupancy traverses another occupancy, the multiple occupancy shall be treated as a mixed occupancy". This indicates that nonseparated occupancies are only allowed in buildings where the different occupancies are mixed together with a shared tenant/owner (The example given by the FM was a School).

Do you all agree with this code interpretation? If so is this just a contradiction between the codes? The 'nonseparated occupancies' provision in the IBC seems to give leeway in many situations where the NFPA would require fire separation.

It also seems to me that the NFPA requirements don't make sense. For example, if I had a 1 story, 1,000 sf building and had half of it office and half mercantile with each space having a separate exit then I'd have to provide fire separation between the spaces. However, if I have the office portion egressing through the mercantile portion and sharing a single exit then fire separation isn't required. This second condition reduces the number of exits in the building and overall safety yet doesn't require fire separation. Nevermind that such a small building is not really a danger from an egressing perspective and fire separation is not a significant life safety concern.

 

[steveray]

It categorizes 'Multiple Occupancies' as either being 'Mixed Occupancies' or 'Separated Occupancies' and also includes provisions for incidental occupancies (appears to be similar to 'Accessory Occupancies' in the IBC). Per section 6.1.14.3 'Mixed Occupancies' appear to be similar to 'Nonseparated Occupancies' in the IBC as it includes the requirement for the most restrictive requirements of each occupancy to apply for the whole building. However, in section 6.1.14.1.2 it states that "Where exit access from an occupancy traverses another occupancy, the multiple occupancy shall be treated as a mixed occupancy". This indicates that nonseparated occupancies are only allowed in buildings where the different occupancies are mixed together with a shared tenant/owner (The example given by the FM was a School).

Multiple treated as mixed does not mean separated....Separated means separated...? The interpretation of "under the same control" would be wrong...

 

[dmoreholt]

Thanks for your reply Steveray. I'm not sure that I follow. You're right that mixed occupancies don't have to be separated and by 'under the same control' I think you're referring to what I said about a 'shared tenant/owner'. I tried to Edit that after but couldn't figure out how. From what I can tell I don't think it matters if it's one tenant/owner. What matters is that they're part of the same shared space and that they have a shared egress path.

My point is that the NFPA doesn't seem to have a similar provision to IBC's 'nonseparated occupancies' as the IBC provision does not require a shared egress path for nonseparated occupancies but NFPA does. This makes the NFPA requirements much more restrictive.

I'm not totally clear on your point so if I've missed it please do clarify.

 

[dmoreholt]

and rereading my comment I should take out 'shared space'. Is there a way to edit comments after posting them? ... New here. The actual language in the NFPA is "Where exit access from an occupancy traverses another occupancy"

 

[steveray]

The actual language in the NFPA is "Where exit access from an occupancy traverses another occupancy"

Correct.....which is just their way of saying if they share egress, they are mixed...Sort of...

 

[dmoreholt]

Right. It sounds like this isn't a fight worth having with the FM, because it appears he's right. Per NFPA any multi use building requires fire separation between uses if the uses don't share egress regardless of size, number of exits, egress distance, whether it's sprinklered, etc.

And so my next question is are the codes just in contradiction here?

If so do you agree with my assessment that the NFPA requirements are overkill? Per their requirements even the smallest building that poses minimal life safety danger would require fire separation between uses as long as the uses don't share egress.

 

[princeofpen]

Right. It sounds like this isn't a fight worth having with the FM, because it appears he's right. Per NFPA any multi use building requires fire separation between uses if the uses don't share egress regardless of size, number of exits, egress distance, whether it's sprinklered, etc.

I haven't spent much NFPA time until late (doing MD projects also) but I see the two codes as pretty much the same. A building under either code is not required to be separated into occupancies "IF" the building meets requirements for the most restrictive. The NFPA CH 6 isn't as easy to understand as T508 of the IBC. If you are in the same category (B,F-1,S-1 for example) you have no requirement to separate or do most restrictive. If you have a B &M for example you have to comply with the most restrictive of height , area, sprinklering etc of the "M" .

The very thought of "any multi use building requires fire separation" is flawed .... why else would they have an option of separated vs non-separated?

 

[dmoreholt]

I see the two codes as pretty much the same.

It seems like that should be the intention of the codes. Unfortunately when I brought up the IBC section on non-separated occupancies the Fire Marshall said he didn't care. It's frustrating working through an approvals process where the reviewers are siloed into different categories and only understand their specific code books. Leaves no hope of having a conversation about code intention and consistency between codes.

From what I can tell the NFPA is very clear that fire separation is always required between multiple occupancies no matter how small the building is and how little thread the occupancies pose to each other as long as they don't share egress.

The very thought of "any multi use building requires fire separation" is flawed .... why else would they have an option of separated vs non-separated?

Right. The IBC non-separated occupancy rules are almost useless with the NFPA requirements for separation.

 

[steveray]

It doesn't say they can't be mixed if they don't share egress.....It just says it HAS TO be mixed IF they do......Right?

 

[dmoreholt]

Steveray, NFPA 101 goes on to say in Section 6.1.14.2.2 that the definition for a Mixed Occupancy is "A multiple occupancy where the occupancies are intermingled". So between that definition and what I said earlier about sharing egress, it seems like a hard case to make that NFPA allows for non-separated occupancies when you have separate spaces with their own exits and tenants (my situation).

 

[thriftwoo]

This may be helpful:

#101Wednesdays: Since multiple-occupancy buildings lead to multiple questions and interpretations, who's right? | NFPA

Image: Wikimedia Commons Over the 20+ years I've been working with NFPA 101, Life Safety Code, the concept of multiple-occupancy buildings hasn't been all that controversial. In fact, I'd go so far as to say it's been relatively straightforward—until recently. Over the past couple weeks, I've...

www.nfpa.org

6.1.14.1.2 Where exit access from an occupancy traverses another occupancy, the multiple occupancy shall be treated as a mixed occupancy.

I'm aware of a jurisdiction extrapolating this to mean where exit access from an occupancy does not traverse another occupancy, the multiple occupancy must be treated as a separated occupancy. This is not the case; the code doesn't work like that. If that was the code's intent, it would specifically say so, and it does not. Part of the confusion arises from the definition of “mixed occupancy” and the use of the undefined term “intermingled”:

6.1.14.2.2 Mixed Occupancy. A multiple occupancy where the occupancies are intermingled.

What constitutes intermingling of occupancies? Based on the mandatory requirements in the code, intermingling occurs where multiple occupancies share exit access paths or lack occupancy separation fire barriers, or both.

 

[dmoreholt]

Thanks thiftwoo! That really nails it. Hard to argue with the source. Mixed, unseperated occupancies don't require shared spaces or shared egress.

Now we'll see what the FM says ...