Can You Tile Your Tub After Putting Plywood Around It?

Exterior Grade

• Normal plywood cannot be used around wet areas, such as bathtubs and showers. You can only use exterior-grade plywood for around the tub, and the proper thicknesses need to be taken into consideration for tile installations. All load-bearing surfaces, such as the tub deck, need to have at least two layers of five-eighths-inch thick plywood mounted in place before the underlayment and the tub are installed.

Underlayment

• Tile should never be installed directly to plywood in wet areas. While you can technically install tile on plywood in dry areas so long as you use the proper type of thinset along with exterior-grade plywood, you cannot do so in wet areas due to the presence of constant moisture. You must always include a layer of cement board or other type of underlayment for the tile installation.

Water

• The one constant with wet area installations is that they are always wet. This means the plywood and underlayment are going to be in the presence of moisture for the entire duration of the installation. Even if you don’t spill water there is naturally more condensation in the air, which transfers into the grout, seeps down into the thinset, the concrete board and eventually the plywood itself.

Waterproofing

• A given in any wet area installation is the inclusion of some type of waterproofing. This can be in the form of silicone caulking on all the inside corners with concrete board and then a layer of paint-on waterproofing on the surface, or it can be an adhesive-backed fiber membrane that goes on like a piece of tape. Some form of waterproofing is necessary on top of the concrete board/underlayment, with the tile installed directly on top of this layer.