Tall brick veneer lateral support

[SocklessJ]

I have a single-story, steel-framed building with a 24' tall high roof. The exterior non-bearing stud wall has a brick veneer, and I'm wondering the best way to handle the deflection from wind.

Is it reasonable to put this all on the cold-formed delegated engineer? Per SSMA, this could work with an 800S200-68 GR50 studs @12" OC. However, I'm not sure if this will be seen as unreasonable and too costly.

I could add an HSS8x8 flush girt to break up the span, but I expect the architect won't like the aesthetics of having to box it out with drywall.

I could add a bypass girt in the plane of the studs, but I'll still need an HSS8x8 due to the 26' bay spacing. So my studs would also need to be 8" deep perhaps negating the cost savings.

How would you handle this situation? Most of my experience is with industrial structures, so interfacing with CFS is new to me.

 

[human909]

While I'm no expert on this aspect of construction it sounds like you are thinking along the right track regarding the need for a wind girt and it will come down to what the client/architect wants and expects. Those wind loads need to go somewhere.

I wouldn't expect that you can just pass this onto the CF engineer. But I don't work in that type of delegation workflow so I don't know.

 

[phamENG]

First question - what design criteria and what loads are you using? There's no real consensus on what value to use. The Brick Industry Association has two tech notes out, one for wood studs and the other for steel studs. The wood studs says to use the IBC minimum of L/240 for service loads (usually 10 year MRI, approximated as 0.42*W where W is your 700 year MRI wind load), while their steel stud document says to go for L/600 for service level wind. At your height, the L/600 is likely prudent. Wood studs are pretty easily height limited, whereas steel studs are much more capable in terms of strength to span further, making a tighter value necessary to envelope all likely scenarios.

The thing about your wind girt - the max deflection will still be deflection of the stud + deflection of the wind girt at mid-span. So it may not tighten up as much as you might wish.

A 24' tall stud wall is big. If you have decent wind loads and the architect doesn't want a girt to make the system more efficient, then they get an inefficient exterior wall system.

 

[XR250]

I don't think it is unreasonable to delegate this or use 8" studs. When I was doing light gage almost full-time, It was common to have projects where the EOR did not even check to see if his strategy was possible or even practical. So I applaud you for taking this step.
Make sure there is a decent place to make a connection for the stud.

 

[SocklessJ]

@phamENG

I was using 0.42W (15psf), with L/600 as a my deflection limit. So it sounds like I'm on the right track.

I was also worried about Girt+Stud combined deflection, and how I'd share the L/600 between me and the delegated engineer. This makes me lean toward eliminating the girt.

@XR250

Just trying to do it right and avoid passing my problems on to others. Now if I could just find the hours....

 

[XR250]

I was also worried about Girt+Stud combined deflection, and how I'd share the L/600 between me and the delegated engineer. This makes me lean toward eliminating the girt.

With the girt, the stud deflection will be pretty minimal. I would not worry about that.

 

[jayrod12]

With the girt, the stud deflection will be pretty minimal. I would not worry about that.

Agree with this, if you keep your girt deflection to L/600 and now your studs are only spanning +/-12 feet, the stud deflection for 8" studs would be negligible.

 

[XR250]

Even for 6", it would not be much. It is also deflecting in a different area of the wall. The stud deflection would be at 6 ft. AFF, while the girt deflection would be at 12 ft. AFF.
Not sure how this affects things, but I don't know any LG designer who takes both into account.

 

[dold]

Per SSMA, this could work with an 800S200-68 GR50 studs @12" OC.

Seems pretty reasonable to me. If you go with a 800S250-68 could you get 16" O.C. to work. Your economy is in stud spacing, slightly bigger stud sections are pretty negligible. I'd shy away from anything heavier than 14ga if possible - harder to screw into for connections.

Typically anything 16ga or thicker will be Gr. 50.

I probably wouldn't bother with a girt.

 

[masonrygeek]

At what point should you consider going with a CMU backing instead of a stud wall? At 24' using a 8" block, the amount of vert reinforcing can be minimal and you would get a more robust wall. If you are going with an 8" deep stud that would have the same footprint as a block wall.

 

[Tomfh]

Both ways are valid. Eliminating the girts is preferred by builders in my experience.

 

[dik]

I've used steel stud walls to about 18' or 20' about 30 or 40 years back. Polo Park shopping centre in Winnipeg.

 

[XR250]

At what point should you consider going with a CMU backing instead of a stud wall? At 24' using a 8" block, the amount of vert reinforcing can be minimal and you would get a more robust wall. If you are going with an 8" deep stud that would have the same footprint as a block wall.

When you decide to pay for it I suppose. I can't imagine the vert. reinforcing would be minimal in a 24 ft. tall 8" CMU wall.

 

[TRAK.Structural]

Echoing some of the others here. Delegating the stud wall system (including the deflection checks) is done all the time, just be sure to have some verbiage about it on the contract documents. Having a girt vs. not having a girt would be something I would discuss with the architect. Present the relevant structural implications for each scenario and let them decide.

 

[XR250]

When you decide to pay for it I suppose. I can't imagine the vert. reinforcing would be minimal in a 24 ft. tall 8" CMU wall.

Also, where would the insulation go?