The term "three-piece-shower" unit is a bit of a misnomer. There are actually four pieces to the basic shower unit. A base unit or drain pan, and three walls. The fourth side of the shower is left open and will serve as a door to the shower and is usually closed off with a shower curtain or some type of shower door. Installing a three-piece shower unit can be quite simple, if everything fits. It can also require some major remodeling efforts if the shower units do not fit the space in the home.
Things You'll Need
Three-piece shower unit
Pry or wrecking bars
Dry wall mud and tape
Installing a Three-Piece-Shower
Accurately measure the space where the shower will be placed. According to the website housetask.com common sizes for shower units are either 36 or 38 inches square. Other sizes are available including designs that fit into a corner with the opening angling into the open area of the bathroom. If the do-it-yourselfer is retrofitting a new shower into an existing space the size of that space is vital to determining the shower that will best fit. Also, measure the placement of the floor drain and the water pipes serving the shower.
Remove walls as necessary and construct new walls to fit the size of the shower chosen. This is only necessary if the space available does not match with the showers available. New stud walls can be covered with greenboard, a waterproof drywall. Mud and tape the greenboard. Stub in plumbing pipes to fit the new shower enclosure.
Attach the base of the shower to the floor and existing drain. Make sure the plumbing joints on the drain do not leak. Follow instructions from the shower manufacturer as to the placement and type of fasteners.
Glue the fiberglass panels of the three-piece-shower unit to the greenboard using construction adhesive. Follow the instructions that come with the shower unit as to the order of placement and how much to overlap the fiberglass pieces. The water pipes should match up with access points in the fiberglass shower walls.
Install plumbing fixtures according to instructions. The controls for the water flow and shower head are usually purchased separately from the shower enclosure. Check all connections for leaks before proceeding.
Seal all seams with silicone caulk. Be sure to caulk around the base of the shower. Caulk all joints where pieces of the shower join and around the fixtures as well. Add trim and finish pieces to the wall area surrounding the shower if necessary.