stryped wrote:
....

I was told by the metal supplier they do it all the time and it does
not sag. The truss manufacturer says drywall is too heavy.

It's done by going perpendicular across the trusses or adding purlins
same way as a wall; your choice. The rigidity in metal is lengthwise
across the corrugation or ridge; lengthwise it has no resistance to
bending much at all and would be quite limber and difficult to install
w/o support.

I'd suggest go to a manufacturer's web site pick a product and get their
recommendations on installation for the application envisioned (or start
w/ the applications and get recommendation on product(s) _and_
installation actually makes more sense).

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