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How To Install a Shower Pan Liner

Shower pan liners are a component of roman tiled or built-up showers. You can buy a pre-formed acrylic shower pan, use a plastic sheet goods shower liner, or build one by layering roofing felt and hot mopped tar over a plywood and lumber substrate.

Acrylic shower pans

This beautiful shower installation starts with a properly installed shower liner

This beautiful shower installation starts with a properly installed shower liner

  1. These units are easy to install right on the plywood substrate without using any further waterproof membranes or building components.
  2. Install the shower strainer in the shower pan using plumber’s putty. Tighten the retaining nut securely because it will be inaccessible once the unit is installed. Remove the excess putty.
  3. The shower enclosure should already be framed.
  4. Cut a 5″ or 6″ round hole in the subfloor to accept the flange of the shower strainer.
  5. Mix up some grout or mortar mix to a relatively thick, pudding-like consistency. Pour this right on the subfloor all around the drain hole and within a couple inches of the shower walls. This bedding material should be not more than 11/2″- 2″ thick at the thickest part.
  6. Embed the shower pan in the grout.
  7. Level the shower pan. Protect the shower pan floor with cardboard or plastic and stand in it to compress the pan into the grout.
  8. While standing in the pan, anchor the pan rim by driving galvanized nails or screws through the nailing flange and into each stud that forms the shower walls.

Built-up roman tile shower bases

  1. The shower enclosure should be previously framed with at least a 4″ threshold across the opening. A hole should be cut into the subfloor to accept the weephole drain.
  2. Install the weephole drain and connect it to the plumbing waste line underneath the floor. Loosen the weephole drain bolts and remove the upper half of the drain first.
  3. Hot mop asphalt or tar on the substrate and put down the first layer of 15 or 30 pound felt, also known as roofing or tar paper.
  4. Ensure that the first layer of felt extends under the weephole drain flange and up the sides of the shower enclosure at least 4″.
  5. Hot mop another coating of tar on the first layer of felt and lay down another layer of the same material in the same way and to the same dimensions as the first layer.
  6. Lay down mortar mix or grout over the felt. Taper it toward the drain. Grade and level it. It should be at least an 1 ½” thick as it nears the walls.
  7. When this sets up, install a pvc shower pan liner or continue with a tile base. If you decide to install a tile base, it is best to lay down several more layers of felt and tar first.
  8. Install the screw-in drain and adjust it to the finished height.

Installing a pvc shower liner

  1. After the mortar base of your roman tile installation sets up, you can lay down a pvc shower liner to provide additional moisture protection.
  2. Cut the pvc sheet large enough so it extends up the shower walls at least 4″ and preferably 6″ or more and over the shower threshold.
  3. Fasten the sheet at the top edge along the wall and on the outside of the shower threshold. Mold it to fit in the corners without cutting.
  4. After installing the pvc shower liner, install a final layer of grout to give the base its finished profile. Then complete the threshold with mortar or grout and add tile or other masonry products to complete your project.


Make certain the joint between the weephole clamp drain and the felt is solid and well sealed.

Verify that sealants, mortar, or grout do not plug the drain holes in the weephole drain fitting.

Install the tile backer board, cement board, or greenboard on the walls so it extends down over the shower liner.

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