Existing "B" Use and "S1" Use newly separated into fire areas to avoid sprinkler - what happens at existing exterior openings

[JustinH627]

Hello-

I can't seem to find a straight answer on the internet or codes - NJ IBC 2018. I am working on a 919 SF office / locker room addition to a 1-story small mixed use service garage - the existing maintenance bays being S1 use (2,051 SF) and existing office portion being B use (2,206 SF). The existing 'B' use and S1 are not currently separated, but the existing wall dividing the areas is 12" CMU. To avoid going over the 5,000 SF area threshold for repair garages (IBC 903.2.9.1) that would require us to sprinkler the building, we are proposing using the existing 12" CMU wall as a 3 hour fire barrier to create separate fire areas, replacing a non-rated interior connecting door with a 3 hour rated door, and adding a 3 hour fire shutter to an interior connecting window.

My question is whether anything needs to happen at adjacent exterior openings, where an existing exterior window that will now be in the 'B' fire area is on the perpendicular CMU wall to an existing overhead door opening in the newly created S1 fire area. The total linear feet in the x and y plan direction (for lack of a better description) is 5'-10". I wasn't sure if separating the building into fire areas with a fire barrier meant it should be analyzed as 2 separate buildings, and if so, if Table 602 would come into affect.

Thanks in advance for any and all help!

 

[cda]

Welcome

Give it a day or two for great answers

Not my area but

Check

706.5.1 Exterior Walls​

 

[steveray]

Generally....no....FB's terminate at the exterior wall and do not create separate buildings...That is firewalls....

 

[instantmessenger]

Can you post a plan, it can be rough? I assume you are servicing automobiles or trucks but it wasn’t specifically mentioned. Is it a private company servicing their own vehicles or is it public?

 

[instantmessenger]

I would say that 602 doesn’t apply since they are the same building. The door for the S1 use needs to be fire rated with automatic sensors though. See 716.2. Check out Cornell doors.