Steel column fire protection within a 2 hour light gauge metal stud bearing wall

[jsnavely261]

I'm working on a hotel project where the walls between guestrooms are load bearing 2 hour rated walls per UL U 469. In a few cases we have a hss column within the stud wall that is needed to pick up some loads from the top floor which is a dining venue. The column meets the requirements noted in section 704.4.1 of being located within the bottom and top tracks of the stud wall. Therefore I believe that the column would not need to be independently protected, but that the membrane of the wall assembly can provide the fire resistance rating based on 704.4.1. Has any else had a similar situation? Am I interpreting this section of the code correctly?

 

[RLGA]

So the columns do not connect directly to any structural member other than the top and bottom tracks of the wall framing, correct?

If so, then Section 704.4.1 would apply. Otherwise, individual protection per Section 704.2 would be required.

 

[Yankee Chronicler]

You are misinterpreting section 704.4.1.

The allowance for membrane [only] protection applies to members that are part of the wall assembly. In other words, if you need a 2-hour bearing wall to support a floor or roof above, the studs withing the wall are considered to be protected by the membrane and do not require indivudual protection.

Beyond that -- walls are rated for protection from one side of the wall to the other. Other than 704.4.1, structural members located within a wall require individual protection using an assembly listed for protection the type of member (in your case, a steel column). If the column requires 2-hour protection, a 2-hour wall assembly does not provide 2 hours of protection for the column.

 

[jsnavely261]

So the columns do not connect directly to any structural member other than the top and bottom tracks of the wall framing, correct?

If so, then Section 704.4.1 would apply. Otherwise, individual protection per Section 704.2 would be required.

Correct, the column is essentially acting as a stud pack.

 

[jsnavely261]

You are misinterpreting section 704.4.1.

The allowance for membrane [only] protection applies to members that are part of the wall assembly. In other words, if you need a 2-hour bearing wall to support a floor or roof above, the studs withing the wall are considered to be protected by the membrane and do not require indivudual protection.

Beyond that -- walls are rated for protection from one side of the wall to the other. Other than 704.4.1, structural members located within a wall require individual protection using an assembly listed for protection the type of member (in your case, a steel column). If the column requires 2-hour protection, a 2-hour wall assembly does not provide 2 hours of protection for the column.

View attachment 15995

The column is part of the wall assembly, it's within the wall cavity. Its not directly supporting a load above, its just there to transfer a point load from above down to the foundation. We could achieve the same thing with a stud pack, but our engineer would prefer to use a column. Why was the word columns added to 704.4.1 in the 2018 IBC of they cannot be used int his manner?

 

[jar546]

The column is part of the wall assembly, it's within the wall cavity. Its not directly supporting a load above, its just there to transfer a point load from above down to the foundation. We could achieve the same thing with a stud pack, but our engineer would prefer to use a column. Why was the word columns added to 704.4.1 in the 2018 IBC of they cannot be used int his manner?

Point of clarification please. The building itself is "light-framed" construction, or the work area you are describing is?

 

[jsnavely261]

Point of clarification please. The building itself is "light-framed" construction, or the work area you are describing is?

Yes, the building itself is light frame construction.

 

[RLGA]

I suppose (I want to ensure everyone that I am speculating here) that the columns may be added to the framing in support of a non-structural-frame building element (e.g., to support a beam for an operable partition, an overhead coiling door, a canopy, a cantilever countertop, etc.).

If it is a supporting part of the building structure, the application of Section 704.4.1 in this situation remains questionable. As the OP stated in their response to my previous comment, the HSS steel tube is used instead of multiple studs grouped together to provide the same loading capacity in a smaller area. If this is indeed the reason, I do not see how the HSS steel tube needs to be individually protected. If the gypsum board membranes can protect a group of steel studs, then a steel tube used for the same purpose should be able to be protected as if it were a group of studs.

In my opinion, the HSS steel tube offers better resistance to the effects of heat than individual studs, as the smaller-diameter tube steel will likely have thicker walls (if you pay attention to the applied fireproofing UL assemblies, the thicker the steel cross-section, the thinner the required fireproofing).

 

[jar546]

Yes, the building itself is light frame construction.

Then I agree, the column does not need to be individually protected. A good idea and design, yes, but not required per 704.4.1.