Installing a Shower Pan Membrane Liner for a Custom Ceramic Tile Shower

What is a Shower Pan Membrane Liner

The only really critical component of a ceramic tile shower is the proper installation of a shower pan membrane liner.

A shower pan membrane liner is the item that ensures any water that may seep through the ceramic tile shower floor gets funneled into the shower drain.

If installed improperly the shower could leak and you’ll end up having to rip out tile and make time consuming and messy repairs. The improper installation of a shower pan membrane liner on a second floor shower can cause even more damage. So you want to make sure you get this part of the project right the first time.

A shower pan membrane liner is made from flexible plastic material. It is sandwiched in-between two layers of mortar on the shower floor area. The ceramic shower floor tiles are attached to the top layer of the mortar. The mortar has a gentle slope to it so that the shower pan membrane liner can funnel water into the shower drain. To install a mortar shower pan membrane liner the first step is to install a pre-slope layer of mortar to the subfloor, be it plywood or a concrete slab.

This “How to Install a Mortar Shower Pan” eBook provides detailed and instructions to install a mortar shower pan right.

What is a Mortar Shower Pan Pre-Slope Layer?

This pre-slope layer is designed to provide a gentle slope from the shower wall edges to the shower drain. After pouring mortar onto the plywood subfloor or concrete slab, it is troweled to create the proper pitch to the shower drain.

After the pre-slope mortar layer has setup the flexible shower pan membrane liner is placed on top of it.

The shower pan membrane liner needs to be properly folded into the corners and tacked in place to the wall studs using roofing nails. The nails that hold it in place should be around 6 inches up from the bottom of the shower pan. In addition, a hole has to be cut in the shower pan to allow the adjustable shower drain to pop up through.

Attaching Cement BackerBoard to Shower Walls

Cement backerboard can then be attached to the shower frame wall studs. Cement backerboard is a cementitious material that is ideal for fastening ceramic tiles to. It is also impervious to water. Do not use drywall or moisture resistant drywall in a ceramic tile shower project. Also, it is critical not to damage the shower pan membrane line while installing the cement backerboard. Make sure to put cardboard over the membrane liner when installing the cement backerboard.

After the final base layer of mortar has fully cured, you can then move onto the process of tiling the shower walls and floor. 

Note that you should use an alkaline resistant tape and thinset mortar to cover the seams in the cement backerboard prior to tiling the walls.

Lastly, after grouting the ceramic tile shower walls and floor, adjust the shower drain assembly so that it is flush with the finished shower floor surface.