5 out of 5HardRequires mid-level plumbing skills
About $200 to $400
6 to 8 hours
In this video, This Old House plumbing and heating expert Richard Trethewey updates a bath.
Steps for Installing a Fiberglass Tub:
- Screw a 2×4 ledger board across the rear wall to support the new tub.
- If necessary, replace the shower valve while the wall framing is still exposed.
- Attach the drain and overflow pipe to the tub prior to installing the tub.
- Apply plumber’s putty around the threaded portion of the strainer.
- Press the strainer into the drain hole in the tub. Place a rubber gasket over the strainer on the backside of the tub.
- Thread the strainer into the drainpipe and tighten with pliers. Remove the excess putty that squeezes out from under the strainer.
- Install the trip lever from inside the tub. Fasten the overflow plate to the tub with two screws.
- Carefully set tub into place against the wall studs.
- Predrill 3/16-inch-diameter screw holes through the tub’s flange, then fasten the tub to the wall studs with 1¼-inch-long decking screws.
- Use a drill and hole saw to cut holes through the fiberglass tub surround for the shower valve and tub spout.
- Stand the fiberglass surround on top of the tub. Slip 2-inch-wide wood blocks under the surround to temporarily raise it above the tub.
- Apply a continuous bead of silicone caulk around the upper edge of the tub.
- Remove the wood blocks and set the surround down onto the tub.
- Predrill 3/16-inch-diameter screw holes through the surround’s flange, then fasten the surround to the studs with 1¼-inch-long decking screws.
- Solder together a threaded copper piece to connect the tub spout to the threaded water-supply fitting inside the wall.
- Tighten tub spout to shower wall, and then screw the chrome-plated strainer to the tub drain.
- Fill the spaces above the tub surround with moisture-resistant drywall. Fasten the drywall strips to the studs with 1¼-inch-long decking screws.
- Conceal the seams in the drywall with joint compound and drywall tape.
- After finishing the drywall, prime and paint the walls with mildew-resistant paint.
- From below the tub, use pliers to tighten the trap to the tub drain.