Connections to Fireproofed Beam

[bookowski]

W21 beams supporting concrete slab. Architect/client would like to provide an angle ledger off of the web of the W21 to support 3x wood joists that are aesthetic only, i.e. it will look like an industrial steel and timber type ceiling but the wood is not actually structural. Do the angles connected the web of the steel require fireproofing over their entire area? If so is there any way to make such a connection, wood (obviously not fireproofed) to steel that does need to be fireproofed? Is there some standoff distance/length that fireproofing needs to be extended along connected members?

 

[jayrod12]

I can't see the supporting angles needing fire rating if they are non structural. However, the connection of the angle to the W21 would need to be fireproofed so you don't compromise the W21. Not sure how you would accomplish that.

How are they getting the fire rating on the W21? The spray on foam? You could just foam the angle as well and then remove the foam off of the bearing surface for the wood connection. Not sure if that would fly with the AHJ.

 

[bookowski]

The 21 would either be spray applied or intumescent paint. I was thinking the same thing, spray the angle but have it 'breached' where the joist sits on it - but not sure if this is ok. There must be provisions for how far f.p. needs to extend along connected elements that are not fireproofed, i.e. what if you hang a steel rod from the beam to support a light fixture, that seems to be a similar situation.

 

[jike]

I would suggest that the horizontal leg of the angle extend beyond the required FP thickness (the W21 web plus angle thickness plus FP) for bearing. I would also add 1/2" clearance between the FP and the end of the wood.

 

[PassiveFireProofer]

One of the possibility would be to use Fire Rated sheet rock 0.625" (Nominal) thick and place two pieces at the interface of the Wood Joist contact at the "ledge". DO NOT USE Intumescent in this Hybrid connection. Select a Medium or High Density Fireproofing (CAFCO 400, Fendolite M-II or Grace 146) to fireproof the W 21 Beam. Deliberately raise your degree of safety by selecting UNRESTRAINED BEAM RATING and ADD 1 hour extra rating than what would be required by Code (IBC 2006??) This should FLY with the AHJ.

 

[PassiveFireProofer]

@jayrod12

I did answer that last night. It is hard to do this without (at least) looking at sketches.

 

[jayrod12]

My fault. Didn't notice your response.