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Installing Shower Baths

Because plastic combination shower baths are so big and bulky, any reinforcing that has been attached to the unit for shipping should be left in place until just before the unit is installed. Also, carefully inspect the unit for damage when it first arrives because damage during shipping isn't uncommon but can be hard to spot.

Assuming that the rough opening has been properly framed—about V8 in. oversize, insulated and air sealed, and with blocking in place—slide the unit into the opening while protecting the finish floor. Don't force the unit if it doesn't fit; instead, back the bath out and use a chisel or a power plane to make the opening bigger. If you force the bath, it might crack later from the stress of being shoved into too small of an opening.

You may have a problem installing both combination bath/shower units and prefabricated shower stalls because usually the plumbing wall is in the side rather than the back, which makes it difficult to slide the unit past the valve and spout or showerhead nipples. One approach is to hold off fastening the blocking holding the plumbing to the framing until after the unit is in place, allowing everything to be pulled back into the stud bay as the bath is slipped into the opening.

Sometimes this isn't possible though, such as when the valve wall is on an exterior wall. In this case, framing the enclosing wall after the unit is in place may be the better option. The unit can then be set against the plumbing wall to get valve locations, pulled away to drill the openings, then set back in place, all without worrying about the enclosing wall making things too tight. It's a good idea to go ahead and lay out and install the sole plate while the rest of the framing is being done, though; it won't be in the way when moving the stall around, and it will ensure that the wall is square and in the right place when it does get framed.

After the unit is in place and is plumb and level, temporarily screw it to the framing through the flange in either corner. Then locate the plumbing openings by drilling small (i.e. 1/8-in.- diameter) holes through the back wall. After the locations have been marked, unscrew the unit and remove it far enough from the framing to freely drill holes for the plumbing. Then drill the proper-size holes from the finish side only, using the small holes as pilots for the larger bits.