What Material Do I Use Underneath a Shower Pan to Make It More Sturdy?

Slipsheet and Mesh

• A slipsheet made of roofing felt or polyethylene sheeting, applied to the concrete or wood surface beneath the shower floor, prevents shower pan movement and keeps the sand mix moist so it can cure naturally. Apply a layer of mesh to allow the deck mud to adhere tightly and form a solid bond with the substrate material.

Using Plumbing-Appropriate Materials

• Your plumbing is likely made of polyvinyl choride or acrylonitrile butadiene styrene. Cementing a matching drain base, using PVC or ABS cement as appropriate, is your next task. This part forms the bottom flange for your clamping drain assembly. At this point you're ready to mix the mortar that creates the sloping base beneath your shower pan.

Sand Mix

• Your local hardware, plumbing or home improvement store can provide you with a sand mix mortar and latex additive to build your sloped pad. Mixing the concrete sand mix with a latex additive rather than water gives the concrete pad more strength as it tapers toward the drain. For optimum results, follow the mixing ratio printed on the product bag or container.

Achieving the Slope

• At the outside perimeter of the slab base, work the mortar bed to a thickness of approximately 1 1/2 inches. Use a trowel to pack the mortar tightly. Gradually vary the thickness of your mortar until you reach a thickness of 3/8 inch around the bottom clamping flange. Use a 2-by-4 to scrape away excess material. Allow your mortar bed 24 hours of curing time before applying the shower pan liner and proceeding with tiling or pan installation.