With the waterproofing system used in this shower, we were able to install the wallboard before waterproofing the shower floor. Instead of installing a curb for the shower, the builder dropped the shower floor framing 3 inches, making it easier to create a drainage slope with an even transition from the bathroom floor. The lack of a curb would make the shower wheelchair accessible for age-in-place clients. Installing a linear drain instead of a center drain meant that the floor could have a flat drainage plane, which would also be more wheelchair friendly.

Prepping the Subfloor

After dry-fitting the drain and checking the slope, I put down a layer of 30-pound felt paper over the subfloor and nailed down a layer of expanded metal lath over that, a subfloor treatment that I’ve used successfully under tile floors for decades. The system acts as a cleavage membrane under the mud layer.

 Starting the Mud Base