After letting the mud pan sit overnight, the shower floor is ready for the heat layer membrane. I used the same Ditra Heat system described in the article “Tiling a Three-Season Porch” (May/19). The Ditra Heat mat also acts as an uncoupling membrane that allows the mud layer and the tile layer to move independently to help prevent cracking.

Laying Out the Sheets

The heat mat comes in sheets, so first I laid out sheets on the mud base, cutting them as necessary to fit the floor. While the sheets were all spread out, I numbered each one for reference.

I picked up all but the first course of membrane sheets and drew a guide line on the shower floor. This line would be the boundary for the thinset that I spread for the first course.

 Thinset for the Heat Sheets