Install Fiberglass Shower using Metal/Steel Studs
I need to install a one piece fiberglass shower stall into a 3' x 3' wall pocket built of all steel studs. Will screwing through the fiberglass shower into the studs be enough to support the shower as it would with wood studs? Or should I replace the steel with wood studs? Or should I put some sort of backing in? If backing is the answer, what is the best way to do this with steel stud for the shower install?
Re: Install Fiberglass Shower using Metal/Steel Studs
The only drawback I see with steel studs is that they are not as stiff across their thickness as wood studs are (but they are more stiff & stable across their width). Since the wallboard on the opposite side and above the shower unit will provide the necessary rigidity, I think you should be fine just screwing the fiberglass flange to the steel studs.
You may need to install backing for the front vertical edge of the unit as well as the edge of the wallboard that meets this edge. What I'd do is place a steel stud so the face meets the flange and the wallboard (twisted 90 degrees in the wall) AND with that stud screwed to a stud installed the normal way to provide stiffness. In a wood wall you can usually get away with a single stud put the "flat" way since it's stiff enough, but a steel stud is too weak to do this.
As for the wallboard, I've seen it attached two ways. The first is to lay it over the shower stall flange. If this is done WITHOUT furring out the rest of the studs in that wall, you end up with a doo-wop in the wallboard there; it won't lie flat. The other way is for the wallboard to meet the flange but not overlap it; the flange is then covered with mud & tape to result in a flat wall all the way to the shower.
Be sure to use water-resistant wallboard above and beside the shower. I haven't tried it, but you can now get "paper-free" gypsum wallboard which is supposedly mold and mildew resistant.
One last point: the wall across from or next to the toilet must be PERFECT. Anyone sitting there has no place else to look; all flaws WILL be seen. And it'll bug you, if it's your house.