Better Thinset Bond Over Plywood Subfloor
Install uncoupling membranes over plywood subfloor properly with this technique. Spritz plywood with water using a garden sprayer for consistent coverage.
When installing uncoupling membranes like Schluter-Ditra over a plywood subfloor, dry plywood can suck the moisture right out of the thinset so quickly that it can begin to dry out, stiffen up, and skin over, failing to form a proper bond with the membrane. Some installers will use a grout sponge to dampen the plywood first, but this can take a long time, tear up the sponges, and result in dry patches in some locations and puddles of water in others.
Instead of using a sponge, I spritz the plywood using an inexpensive garden sprayer filled with clean water. Using a sprayer is easier, allows me to cover large areas quickly, and results in more consistent coverage. I spray less water on the section I’ll be working on right away and more on those areas that I won’t get to for a while. I often use the same technique when applying thinset to cement backerboard as well.
—Chris Wand, Lafayette, Colo.
Illustration by Charles Miller
