How to Replace an Acrylic or Lead Shower Pan
Many homes in America have showers that are located in a separate stall instead of being part of a bathtub spout and diverter system. As time passes, the shower may leak causing damage to the flooring and possibly the ceiling below. Original shower stalls were lined with heavy lead sheets that had been formed into the base of the shower and filled with a dry mortar bed and then tiled over. Newer homes will have standardized acrylic shower pans that can crack and leak over time. This article will discuss how to replace shower pans with a standard acrylic pan and a PVC sheet material for larger or irregularly shaped showers.
Reciprocating saw, used to cut out old acrylic shower surround.
Rubber mallet, used to install compression gasket to drainpipe.
2 and 4-foot level
Steps for Removing and Installing and Acrylic Shower Pan
1. If your shower is tiled, and you want to keep the tile, you will need to remove at least 2 courses of tile to have enough room to set the new pan and nail it into the framing.
2. Cut out old acrylic shower surround with a reciprocating saw, and remove the surround.
3. Most likely the wallboard behind the surround is damp not water-resistant. Remove this as well.
4. Saw through drainpipe connected to old shower pan; remove shower pan.
5. Set new acrylic shower pan on floor and check its fit against the studs.
6. If necessary, build out studs with ½-inch plywood strips so pan clears any obstructions.
7. Mark shower pan's drain hole onto the subfloor; also mark if pan overlaps the floor tile or grout in the bathroom.
8. Remove shower pan.
9. If necessary, use hammer and cold chisel to chop out any tile or grout that extends under the pan.
10. Attach the strainer to the drain hole in shower pan.
11. Vacuum the subfloor clean of all dust and debris.
12. Check floor with a 4-foot level; install shims to create level surface.
13. Set shower pan into place and check for level.
14. Secure shower pan to studs with stainless steel screws; be sure to drill pilot holes first.
15. Dry fit new PVC trap to drainpipe; glue together the PVC parts using primer and cement.
16. Connect drainpipe to shower pan's strainer with a compression gasket; use a rubber mallet to tap gasket and pipe flush with shower floor.
17. Install the screen to the strainer in the drain hole.
18. Complete the installation by covering the walls with cement backer board for tile or water-resistant drywall for a surround. Install tile or another acrylic surround.
Removing and Installing a New Shower Liner
Plumbers originally installed lead shower pan liners because they were cheap, easy to work with, and they were plumbers who had ready access to lead. Today several manufacturers make leak-proof membranes for showers, Chloraloy® is one of the most widely used membranes. Tiles cannot be attached directly to a shower pan membrane, so a dry mortar bed has to be installed over the liner. This bed is sloped towards the drain before it sets and then tiled over.
1. Remove the tile from the base of the shower and at least 12 to 18 inches up the side of the wall. If you are going to retile, remove the tile working from the top down.
2. With a hammer and chisel, break out the original mortar bed and remove.
3. With a flat bar and hammer, pry out the nails from the studs and remove the lead sheet. It tears easily if the pan is large; place the lead in a heavy garbage bag. Take the lead to your local hazardous waste collection facility or keep until your town has a hazardous waste collection day.
4. Vacuum all debris in the shower.
5. Most modern membranes require a mortar bed beneath the liner to support it and protect it from being damaged by the subflooring. Follow the directions for the manufacturer or you shower pan liner.
6. Install the new membrane after the base mortar bed has cured. Note: If your framing is damp from the original leaking liner, let the area dry completely before installing the new liner. Spray the area with bleach or distilled vinegar if there is mildew or mold.
7. The new shower drain will have a clamping ring specially designed for use with membranes. Follow the directions for your drain ring.
8. Measure the shower pan area and transfer those dimensions onto your new liner. Add 8 to 10 inches to each side so it can run up the wall or over the threshold.
9. Once the membrane is centered in the shower, the excess is carefully folded into the corners. Secure the fold to the framing with one roofing nail along the top edge. Nail the upper edge of the liner at each stud, always keeping the liner square to the wall and taking care not to pull it off the floor or stretch it.
10. Mark the heads of the four drain-assembly bolts where they touch the membrane.
11. Make a small slit for each bolt and push the membrane down over the bolts; cut from bolt to bolt in a circle following the inside of the drain. Cuts should always be made toward the inside of the drain to avoid slipping with the knife and cutting the floor area of the membrane.
12. Lift the liner around the drain and make sure the bottom plastic ring is clear of dirt or grit and apply sealant to underside of the membrane and to the top of the drain-assembly flange.
13. Press the membrane and drain flange together, place the top ring in position and slowly tighten the bolts, applying equal pressure on each bolt.
14. Install the dry mortar layer on top of the membrane. Use a 4:1 mixture (sand-to-Portland cement) and mix the cement to a consistency that forms a ball when compressed in your hand. Mix in batches in a 5-gallon bucket. Slope to the drain using ¼-inch per foot. Use a piece of tile as a guide so that the surface of the tile is slightly higher than the drain and slopes up to the walls.
15. Tile over the shower pan once the mortar bed has cured. About 24 hours.
Hopefully you will be able to tackle this job yourself, it will take at least a weekend to remove an old shower pan and tile and install the new one. It will take an extra day to install a membrane for drying time of the base mortar bed.