Fire Barrier Construction - Separated Uses, Exterior Wall

[texasbo]

Sorry to just come by when I need help, but would appreciate input. I'll try to limit the description to only the necessary information.

Mixed use building, single lot, fully sprinklered. Fire Barrier is required between B and S2 parking garage (due to allowable area and height issues) . Above grade level S2 parking garage are 3 stories of R2 condos. Therefore, the Fire Barrier separating the B and S2 on the first floor becomes an exterior wall for the R2 on floors 2,3,4.

Question: The code is pretty specific on how to treat a Fire Wall in a building of different heights. However, I can find no such language for Fire Barriers. Can this Fire Barrier stop at the underside of the roof structure for the first floor, as I believe, or does anyone feel that there must be some wall/opening protection on floors 2,3,4?

Thanks

 

[tod13511]

I think you’re right. Fire barriers are only required to extend to the exterior wall (and roof deck, I guess). There are no requirements for rating exterior walls like 706.5.1 for fire walls or as you pointed out for rating roofs like 706.6.1 for fire walls terminating at a lower roof. The way I understand the description, the B roof is directly under and outside the R-2 exterior wall (and windows). This all seems a little funny since we know that fire burns up, but it says what it says.

I might try to use 705.8.5, Vertical separation of openings, to limit the roof openings, but since the building is fully sprinklered, they would meet an exception.

I’m really unclear on this building design. You make it sound like 1 building with 1 construction type. Usually when I see R-2 on S-2, it’s sticks on concrete, like 509.2 or 509.4. I’m curious what the construction type is and what the B/S2 footprint is.

 

[texasbo]

I’m really unclear on this building design. You make it sound like 1 building with 1 construction type. Usually when I see R-2 on S-2, it’s sticks on concrete, like 509.2 or 509.4. I’m curious what the construction type is and what the B/S2 footprint is.

Thanks tod. Ironically enough, this is relating to T.O.D., which is also the main reason I haven't been around much in a couple of years.

I didn't want to cloud the answers with extraneous information, but yes, we usually see sticks on a podium. This is IIA with fire resistive substitution. The barrier is required because there is some A2 mixed in with the B, and A only gets 3 stories. So partial separated uses (using the fire barrier to separate the 1st floor B/A from the S2) keeps them within allowable areas and allows the 4 story S2 and R2.

Thanks again.