Prep a Subfloor for Tile
A second layer of plywood stiffens floors for long-lasting tile installations.
Synopsis: This article covers the basics of installing plywood underlayment for use below ceramic tile. It discusses subfloor preparation, panel layout, and fastener spacing.
As a carpenter, I installed thousands of square feet of plywood underlayment over subflooring that the framers had fastened to the floor joists. Plywood underlayment can be used directly under tile in many instances, and it might still be necessary even if you’re using cementboard or one of the plastic isolation underlayment systems. For example, many isolation systems require the use of plywood underlayment with joists on 24-in. centers. These products make great tile bases, but they don’t strengthen floors like plywood does. Plywood underlayment helps to share loads between joists, reducing the overall deflection of the floor, and it reinforces the subflooring to stiffen the floor system between the joists. This is important because ceramic tile is pretty inflexible, and movement in the floor below…