DIY Network

How to Lay a Subfloor

Before installing a tile floor, a subfloor and underlayment is necessary. The experts show how to install the subfloor in a bathroom.

More in Floors

  • Time


  • Price Range

    $50 - $100

  • Difficulty



Step 1: Mark the Cut Lines

Use a T-square to mark the cut lines on the plywood.

mark cut lines on plywood using T square

Step 2: Cut the Plywood

Cut the plywood to size, running the circular saw across the width of the board.

cut plywood to size with circular saw

Step 3: Mark the Joist Locations

Using the original sub-floor nails as a guide, mark the floor joist locations on the wall to know where to insert the screws.

mark floor joist locations on wall

Step 4: Lay the Plywood

Lay the plywood in place on the floor.

lay plywood in place on floor

Step 5: Insert the Deck Screws

Run a chalk line off the floor joist to mark the wall. Then, drive deck screws every 8 inches along the line.

drive deck screws every 8 inches along chalk line

Step 6: Attach the Cement Board

Bring in the cement board and lay it down on the plywood (Image 1). Screw the cement board into the plywood about every 6 inches (Image 2).

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