How to Put Down Tile Backing Board

A durable tile floor starts with backer board.

Floor tile will loosen or crack if it isn't installed on a firm, immobile underlayment. Plywood and other surfaces can work under the right circumstances, but nothing's better than a thick layer of cement board. This is a material specially designed for laying tiles. It comes in sheets like drywall but is much stronger and is waterproof. It's set onto your subfloor with thin-set mortar, the same material you'll use to set the tiles, and screwed down with galvanized screws that won't rust.

Things You'll Need

• 5/8-inch cement board sheets
• Pencil
• Thin-set mortar
• Mortar trowel with notches on one side
• Screw gun
• 1 1/2-inch galvanized wood screws
• Tape measure
• Jigsaw
• Mesh drywall tape
• Nonpowered hand sander
• Drywall sandpaper

Instructions

1. Set a sheet of cement board in a corner of the room. Trace around the perimeter of the board with a pencil. Remove the board. Spread thin-set mortar over the marked-out area, using the notched side of your mortar trowel.

2. Put the cement board back in place. Walk on it get it pressed firmly into the thin-set mortar.

3. Use your screw gun to drive 1 1/2-inch galvanized wood screws through the board's surface. Insert a screw about every 6 inches throughout the board. Completely sink the screw heads so you can't feel them when you run your hand over the board.

4. Lay the next piece of cement board in the same way, at the end of the first board. Proceed to lay additional boards, end to end, setting them in mortar and screwing them down. Cut the end pieces as necessary with a jigsaw. Stagger the seams between the rows of boards so they don't form any four-way intersections. Cover the whole floor.

5. Press mesh tape over the seams, getting it flat and well-adhered. Spread thin-set mortar over the tape with the flat edge of your mortar trowel. Smooth the mortar completely so it's flat with the surface of the boards. Scrape a little mortar over each screw hole.

6. Let the mortar dry for a day. Sand it lightly using a manual sander loaded with drywall sandpaper. The floor is ready to be tiled.

Tips & Warnings

• Wear goggles when cutting the cement board.

References

• HammerZone: Installing Cement Backer Board