Built from concrete, a mortar shower pan, also known as a mud shower pan, is found in bathrooms and usually has a sloping design which serves as a shower base. Although there are pre-fabricated mortar shower pans available, a do-it-yourself shower base can also be built. Here are the steps in creating a DIY mortar shower pan.
For an area of approximately four to five square feet, an 80-lb bag of cement is needed as well as a vinyl liner about 12-inch in size and should be relatively wider than the shower.
To cover the floor, you will need a galvanized metal lath with a width of more than 12 inches that can be used to accommodate curbs. For forming the curbs, hardboard sidings, as well as 2×4 material pieces, are needed.
For cementing the board, fiberglass tape is needed for the seams and nails, 1-1/4-inch nails are needed to fasten the membrane and cement board.
Frame the shower curb. With several stacked 2x4s, build the core of the curb. Screw the 2×4 material into the subfloor and screw another 2×4 to the already fastened material.
Cover the shower pan plywood. Before constructing the shower pan, it is important to use a layer of roofing felt at the bottom of the pan. This is important to separate the subfloor from the shower pan and to keep the moisture in the mortar during the curing since the tar paper or asphalt felt serves as a moisture barrier. For the installation of the asphalt felt, there should be a cut around the drain base and the surface of the subfloor should be covered. Secure the felt to the wood with the use of galvanized staples.
Create shower pan box. Build a box with wood material, using it as a blocking for the wall framing. In this step, you will need plywood, around ¾” in size and 2×6 boards.
Base shower pan and wire the curb. Strengthen the mud layer of the base floor with a galvanized wired mesh. This will also support the mortar to the shower curb. Embed the mesh by bending it a little to create “waves” in the mesh and place the mesh over the framing of the curb. Secure using galvanized staples.
Prepare floor mix. Create a mixture of mud, cement and water for a clay-like consistency. First, mix the cement with sand with a shovel before pouring water. This will ensure a strong and stable mixture.
Build first layer of shower pan and install liner. Using the mud mixture, build the first layer with a slope towards the shower drain from the wall, with ¼ to 3/8 inch per foot. Ensure to cover the studs with stucco wire smoothen the surface. Let this dry overnight. After, lay the continuous sheet of liner to cover the floor and secure it using liner adhesive or silicone caulk.
Install drain clamp. Locate the drain and secure the drain clamp using bolts. After, insert the drain throat or drain riser.
Install backer board and second layer of the mortar shower pan. Secure the backer board in place and add the second mortar layer by pouring it on top of the mortar liner. Cover it with mud mixture and smoothen to finish the mortar shower pan. Let it cure for about two days.