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Occupancy Class Uncertainty

N

NewGuy

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Joined
Jul 27, 2025
Messages
2
Location
Alaska
Hello everyone,

I have been trying to determine the occupancy class for a detached trailer that is no further than 5 feet from another building. Some facts:

The trailer is used as office space and has been there years before me. The trailer does not share exits or exit egress but may share exit discharge with the other building. It is located on the ground floor with an occupancy below 20. The nearest building is a carpenter shop. Both buildings are controlled by the same company. I have been informed there is no AHJ due to the location of the facility, which does not sound correct to me. I also requested the plans to try to determine fire separation but that has materialized. The buildings are interconnected by piping for a restroom in the trailer.

I have looked at both the NFPA 101 and the IBC and have been uncertain of what the occupancy classification for the trailer would be. Would it fall under business? (101) This is relevant to determine fire alarm system requirements. What other details would be necessary to correctly make this determination? If it is as plain as it reads and I look at chapter 39 of the NFPA 101, it would seem to me that the trailer alone would not require a fire alarm system but that does not sound correct. Trying to verify where I’m going wrong. Any help would be appreciated. Thanks!
 
You mentioned this is a trailer. In some states, if something is on wheels then it's not regulated by the IEBC and/or IBC (not sure about NFPA 101) and is regulated by state transportation rules/laws.

If it's not on wheels then it may need to be treated as a structure on an lot with another structure and requirements/allowances that come with this. You indicated the purpose of the trailer is office space so, based on this, I'd agree that this is a Group B Occupancy and this accessory structure should follow code requirements for that use.

Wish I could help more but, with no AHJ, they might not have to anything. There are areas of the US where codes are not adopted and permitting is not required but insurance companies are becoming more involved in when permitting can be required. I wouldn't be surprised if they required some type of fire and life safety and structural analysis to support policy limitations and rates.
 
That was plenty helpful. Thanks! I have had a few discussions with various people both in and out of the company and the general consensus so far has been to treat it as an accessory and classify it is Business Occupancy. Best practice would be to come up with a method of notifying the occupants of the trailer without it being a fire alarm system, so that is what I will bring up for discussion.
 
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