Wood Stair Landing Connections at Fire Rated Shaft

[AustinStructural]

I have a job where the stair landing headers were detailed to be pocketed in to the walls on either side for bearing. However, after reveiwing IBC Sec 707 I see that penetrations are not allowed in the shaft walls. This particular project requires a 2 hr. rated shaft since it is 4 stories in height.

My question is, what is a good way to detail the end connections for the headers (stringer support beams) to transfer the load to the wall?

I have looked at details that show the beam end with a top flange hanger attached to a 2x ledger which is then lagged in to some blocking between the wall studs. But is it safe to rely on lag screws in bending where they pass through 2 layers of 5/8 gyp?

I would have thought that stair connections in a fire rated shaft would have been a topic of discussion at one time or another, but all of my searching has turned up nothing? Maybe someone here has dealt with this before and can offer sound advice?

Thanks in advance.

 

[hokie66]

I can't give you an answer because I am not familiar with the IBC, but logically the fire rating is to keep the fire out of the stair. Once it is in the stair, it is too late.

 

[AustinStructural]

Thank you hokie66. I realize the importance of not penetrating the shaft. My question is how to appropriately connect the stair landing framing to the shaft wall.

I have run some quick numbers and I am finding that the header reactions can get fairly large, especially where there is no intermediate support on the span. It seems that the connections through the gyp could get a bit messy and I am hoping someone has a practical approach to the solution.

 

[hokie66]

What I was implying was that you should be able to penetrate the layer of gypsum board on the inside of the stair to connect your stair members. You can't rely on connections through the gypsum board. If no penetrations are allowed, you may have to independently support the stair with posts in the corners.

 

[jike]

I was going to suggest posts also.

 

[diarmud]

Conisder contacting a local rep of National Gypsum or any gyp board dealer. They usually have very detailed clear brochures which show how to detail something like this (especially for fire ratings). I don't know as I deal in residential only.
Good luck,
Dermott