Interior Metal Stud Partition Wall Lateral Support

[rfq]

I've got a client who has done some tenant fit-up work inside a multi-tenant industrial building. For the office areas he as a suspended ceiling with several 3-5/8" metal stud interior partition walls which extend 6" above the ceiling typically. They have braced some of the walls by connecting studs diagonally between the top tracks of adjoining walls. This is what I've seen in the vast majority of similar projects here (in Ontario, Canada) over the last 20 yrs.

However, the plans examiner has asked us to assess the adequacy of the partition walls lateral support. The design load for this type of case would be approximately 5psf (0.25 kPa). The design catalog for the stud manufacturer states that the suspended ceiling would serve as lateral support however this is not something I can easily prove. Any ideas how I should deal with it? Perhaps proposing additional bracing to the top track? The problem is that the walls are approximately 10' high whereas the roof deck of the building is at 30ft.

Any suggestions would be greatly appreciated. I am not worried about the behaviour of the walls, but I'm stuck as to how to justify it to the plans examiner in a feasible way.

 

[DaveAtkins]

I dealt with a similar problem about a year ago (but in my situation, the 3-5/8" X 25 GA studs were not adequate for the floor to floor height). I discovered that the stud manufacturer on my project, Dietrich, would not say that a suspended ceiling can brace an interior steel stud wall. I believe the UBC (or some model code) formerly did allow this, but I don't think anyone supports this opinion anymore.

I ended up putting in 3-5/8" X 20 GA girts just above the ceiling, and diagonally bracing the girts to perpendicular walls. Basically, the perpendicular walls act as shear walls.

I believe you will need to do something similar--the studs can't be 30' tall.

DaveAtkins

 

[rfq]

The catalog I'm using (Bailey Metal Products) states the following: "... where studs are rigidly braced at or below the maximum height(by suspended ceiling or separate bracing) ..."

I think that I will respond that the ceiling is going to provide this lateral support and hopefully this will satisfy them. If not I will pursue it further.

Thanks for your reply.

RQ

 

[UcfSE]

Can you add in some tension bracing along the ceiling grid to brace the top of the wall? This could be some hanger wire, perhaps No. 8, or 1.5-inch cold-rolled channel anchored to the exterior walls. You may have problems getting the wire tight enough to act as bracing without having to deflect until it gets taught.

If you have enough perpendicular walls, I think Dave's idea is a good one.

I would not just assume the suspended ceiling braces anything. These are typically pieces that are fit together like puzzle pieces and might have a screw in some locations. That is not to say you cannot add framing yourself to make the ceiling function like you want, but that would be unusual and likely to get messed up or overlooked in the field.

 

[rfq]

I have a significant number of perpendicular walls so my largest unsupported span in any direction is somewhere around 15ft. There is suspended ceiling on both sides of every partition wall (except the wall dividing warehouse and office which is a full height 6" - 16ga structural metal stud wall)so I do think it provides significant lateral support. In any case, they have also provided the lateral support from the top of each wall to perpendicular partition walls.

I'm not sure what the situation is in other parts of the world, but up here it's getting more and more the case that construction is *complete* prior to getting a full building permit(!) This makes it very difficult to satisfy the building officials when things are already constructed. (Grrr!)

RQ

 

[azcats]

I had a problem similar to this before, however only about 20% of my rooms had ceilings and the shell structure was at over 30'. I ended up using heavy top tracks to span horizontally b/w perpendicular walls. On some really long walls I did use braces angled back to perpendicular walls.

I doubt that your contractor will want to do anything like this.

 

[BSE05]

I have used corner bracing (45 degrees) at the top track. This will work if the rooms are not too large. Run the numbers and size the top track accordingly for the horizontal load. Brace to building columns and shear walls whereever possible. I agree not to count on the suspended ceiling for lateral bracing.

Although I have seen a lot of jobs (by architects and not structural engineers) where the wall studs stop under the suspended ceiling.

 

[MikeE55]

Section 1621 of the 2000 IBC addresses this issue. Suggest you read it, but I interpret it to say walls must be braced to the structure unless they are not taller than 9 feet and the horizontal seismic load does not exceed 5 psf. Then ceiling attachment is enough.