CBC 707.5.1 Supporting Construction for Fire Barriers

[knelson]

I've been trying to find something that helps define "supporting construction". I'm working on a Type IIB, 3-story high school building. (We're using the sprinklers for the added story since we can meet the allowable area without any increases for sprinklers.) We're using the Type IIB construction exception for the supporting structure having to be the same rating as the corridor walls. We're also using that for the incidental accessory occupancy separation walls, but there isn't an exception for the shaft walls. What is the extent of the structure that has to be rated the same as the shaft walls? Is it the floor that supports the rated shaft walls and the columns and beams that support the tributary loads for the floor?

 

[Coug Dad]

706.5 (2006) states that all supporting construction for a fire barrier must match the fire barrier rating. I have typically seen this include all structure out to the next column line. It is an AHJ call though.

 

[cda]

Maybe???

http://www.thebuildingcodeforum.com/forum/commercial-building-codes/5145-707-5-1-supporting-construction-protected-how.html

 

[knelson]

We will probably use spray-applied fire-proofing since it's a steel structure with metal deck/concrete fill for the floor.

 

[Coug Dad]

Are you the AHJ or DP?

 

[knelson]

I'm the DP

 

[steveray]

Complete load path all the way to the foundation.....what irks me a little is when the FB is braced to an unrated ceiling........