Pre-Engineered metal buildings with Interior Gypsum Walls

[OHIOMatt]

I am at a bit of an impasse. I have a design/build project in which the general contractor wants to use a pre-engineered metal building as the frame and walls of a single story office. The architect (my client) has shown the use of gypsum wall board over metal studs which are supported by the building girts. I have been contracted to design the foundations only, but when seeing the detail posed the question as to if deflection had been considered. During a conference call today, I discovered that the wall girts are designed with a wind load deflection of L/90. Obviously this far exceeds what the gypsum can be subjected to without cracking. Have any of you run into this before? I am thinking of suggesting wall studs that span from top of stem wall to a beam (designed by me) meeting the wall board deflection criteria. The studs would be used to support the girts which are still needed due to the siding.

Does anyone have a better idea?

 

[XR250]

Isn't sheetrock ok for L/120? Did they take a 30% reduction in wind pressure when calculating L/90? If not, you would squeak by. (my guess is that they did as they want to use the least material possible)
Gotta love metal building specifiers!

 

[Ron]

Ask the architect if he wants his client's interior walls to breath every time the wind blows? Move the interior walls inboard a bit more, anchor well at the floor and attach the walls at the top only using a diagonal strut.

 

[jgailla]

I've never designed them, but I've built out quite a few interiors of PEMBs. I've never seen the interior walls connected to the structure.
The interior walls are stand alone and braced above the drop ceiling. Even fire walls are only connected to the beams or columns, not the girts.

 

[msquared48]

Do not span the studs vertically. The wall sheeting will not be properly supported if you do so since the ribs of the sheeting run vertically. Either increase the size of the girts, put the walls inboard of the girts, or forget the sheetrock.

Mike McCann, PE, SE (WA)