Fire-separation between units of multi-unit commercial building

[Green-rev]

Hi,
I am currently working on a new construction commercial project that has (5) separate units inside (1) building. The owner is looking to rent out the units without knowledge of the future tenants or their end use. The overall size of the building is 10560SF and is being built as non-sprinklered, VB. Since, we don't know the end use of the units, but knowing that the most obvious uses will be B, M, S-1, and/or F-1, I am looking at using the most restrictive of each to ensure that we meet code. With allowable increase for frontage, we are permitted up to 13513SF using the most restrictive allowable building area, F-1. We are able to meet all requirements for a non-sprinlered, non-separated, mix-use building according to the 2018 IBC. The issue we are having is that AHJ wants us to use 2-hr fire-rated walls as the separation wall between the units. I tries to explain that the building meets code without having the fire-rated walls, but he is sticking to his guns. Am I missing something in the codes that states you need fire- separation between individual units in the same building? Does the AHJ have the right to make us go above and beyond the code to appease their minds? I appreciate any insight.

 

[classicT]

Seems that the AHJ is trying to apply Separated Mixed Use per 508.4, when you are trying to apply for Non-separated Mixed Use per 508.3.

Obvious question then becomes, have you pointed to IBC Section 508.3.3?

508.3.3 Separation
No separation is required between nonseparated occupancies.
Exceptions:

1. Group H-2, H-3, H-4 and H-5 occupancies shall be separated from all other occupancies in accordance with Section 508.4.
2. Group I-1, R-1, R-2 and R-3 dwelling units and sleeping units shall be separated from other dwelling or sleeping units and from other occupancies contiguous to them in accordance with the requirements of Section 420.

My only other comment is to review IBC Section 903.2 and any local amendments made by the AHJ, for when a fire sprinkler system is required. Given the total area of the proposed building, you most likely will not be tripped up. That is unless you have a tenant storing or selling upholstered furniture or mattresses.

 

[Green-rev]

Thanks, Ty.
I did point out the 508.3.3. It seems that the AHJ is ceding to the Fire Marshal, and they are saying that "they" want to see at least a one-hour rating, down from a two-hour rating that they originally said we need. There doesn't seem to be any code, IBC or local, that they can cite to justify. At this point, its probably just easier to add a layer of 5/8" on each side and be done. It's a bit of a cost increase, as we were just doing steel liner panel, but much easier and faster than having to go to the state to mitigate. It's just frustrating and something to think about when dealing with this jurisdiction in the future.
Also, I did review 903.2 and you are correct. We are good on all exceptions, except for the upholstered furniture and mattresses. That is easily amended by the owner not allowing that type of storage in the building. However, each unit is 1950SF, so technically one unit would be able to store those items. At least, that is what I am reading.

 

[classicT]

I have seem some AHJ apply IBC Section 402.4.2.1 for separation of tenant suites; however, I strongly disagree with this practice, as Section 402 only applies to mall buildings.

402.4.2.1 Tenant Separations
Each tenant space shall be separated from other tenant spaces by a fire partition complying with Section 708. A tenant separation wall is not required between any tenant space and the mall.

COVERED MALL BUILDING. A single building enclosing a number of tenants and occupants, such as retail stores, drinking and dining establishments, entertainment and amusement facilities, passenger transportation terminals, offices and other similar uses wherein two or more tenants have a main entrance into one or more malls. Anchor buildings shall not be considered as a part of the covered mall building. The term "covered mall building" shall include open mall buildings as defined below.

Mall. A roofed or covered common pedestrian area within a covered mall building that serves as access for two or more tenants and not to exceed three levels that are open to each other. The term "mall" shall include open malls as defined below.

Open mall. An unroofed common pedestrian way serving a number of tenants not exceeding three levels. Circulation at levels above grade shall be permitted to include open exterior balconies leading to exits discharging at grade.

Open mall building. Several structures housing a number of tenants, such as retail stores, drinking and dining establishments, entertainment and amusement facilities, offices, and other similar uses, wherein two or more tenants have a main entrance into one or more open malls. Anchor buildings are not considered as a part of the open mall building.

 

[RLGA]

"They" can request all they want, but unless they have a code citation to back their request, then "they" cannot request more than what the code requires. If the issuance of a permit will be withheld, then I suggest using the appeal process. If you don't have the time to go through the appeal process and the owner doesn't want their project delayed, then you may have to acquiesce and press on. You may try getting an ICC staff code opinion to see if that will help them "see the light"--if you are an ICC member, this process is relatively quick and doesn't cost anything.

 

[Green-rev]

That is an interesting point, but I agree, according to the definition of mall, as stated in 402.4.2.1, this is not a building with a common pedestrian area. This building is more of a storage facility for tradesmen to store their equipment and supplies or, at best, a small production facility. I have been to a brewery that was operating out of a storage facility (they retrofitted a few adjacent units), and thought that was a bit interesting. You had to literally drive around a storage facility looking for the brewery. I guess it was a cheap way to start up until moving on to bigger things, but it does kind of raise some eyebrows.

 

[Green-rev]

Thanks for the input, Ron.
I totally agree, but the owner is just going to add the fire-rated walls. They had been thinking about doing it for their own peace of mind anyway, so I guess no harm, no foul. It's good to know that I wasn't overlooking something in the codes that I should know about.

 

[khsmith55]

Thanks, Ty.
I did point out the 508.3.3. It seems that the AHJ is ceding to the Fire Marshal, and they are saying that "they" want to see at least a one-hour rating, down from a two-hour rating that they originally said we need. There doesn't seem to be any code, IBC or local, that they can cite to justify. At this point, its probably just easier to add a layer of 5/8" on each side and be done. It's a bit of a cost increase, as we were just doing steel liner panel, but much easier and faster than having to go to the state to mitigate. It's just frustrating and something to think about when dealing with this jurisdiction in the future.
Also, I did review 903.2 and you are correct. We are good on all exceptions, except for the upholstered furniture and mattresses. That is easily amended by the owner not allowing that type of storage in the building. However, each unit is 1950SF, so technically one unit would be able to store those items. At least, that is what I am reading.

You may want to think twice about appeasing the Fire Marshal. It's not just adding a layer of 5/8" on each side, occupancy separations must be Fire Barriers (i.e. continuous to the bottom of the deck above) not Fire Partitions. I would hold my ground and design it as a non-separated mixed use building.

Ken

 

[classicT]

You may want to think twice about appeasing the Fire Marshal. It's not just adding a layer of 5/8" on each side, occupancy separations must be Fire Barriers (i.e. continuous to the bottom of the deck above) not Fire Partitions. I would hold my ground and design it as a non-separated mixed use building.

Ken

If the AHJ is making up the requirement, it is whatever they say it is. If they are good with a 1-hr rated wall, then that's what they will get. Note that the AHJ, per the OP, has not specified any code section to back up their requirement. Therefore, we do not know if the wall is just a fire-resistive wall, a fire partition, a fire barrier, etc.

Anyways, if it were a fire barrier, then you'd move on up to a 3-hr rating per Table 707.3.10 (S-1 has highest value).

 

[Green-rev]

I believe they are considering the divider walls as fire partitions and do want the drywall to run from floor to roof deck. I think this is strictly a CYA on their end, so this their compromise- do a 1-hr rated wall instead of 2-hr and we'll call it square. I don't have the time or energy to run it through the state, so we are just going to have to bite the bullet.

 

[TheCommish]

it would be prudent to do a one-hour wall floor underside of the roof deck, with appropriate roof decking that can be upgraded to 2 hours if needed by the tenant fit-out, which would require its own permit after the shell and separations ar built.