Floor Tile Backer Board Or Subfloor

If the subfloor doesn t have enough stability you can usually but not always remedy the situation by installing cement backer board also called cementboard.

Floor tile backer board or subfloor.

Floor tiles should be installed over smooth flat surfaces. It is generically called cement board or backer board or it can also be referred to by one of the common brand names such as densshield hardiebacker and wonderboard. Spread the mortar to about 3 16 thickness. Lay the backer board according to the manufacturer s instructions.

Cement based backer board. According to backer board manufacturers and tile setters installing backer board directly over an old solid wood subfloor is risky for a couple of reasons. First changes in humidity make solid wood shrink swell and cup more than plywood. Second the strength of wood boards isn t always consistent.

Now largely regarded as the very best underlayment for ceramic tile in any application floors walls and countertops cement based backer board goes by many names. The backer board is then secured with screws to the subfloor beneath. When installing a ceramic tile floor on a concrete subfloor you don t have to worry about flexing as long as the concrete slab is at least 1 1 8 inch thick which most slabs are. Also if your subfloor runs east to west lay your backer boards in the opposite direction north to south.

Plan so the joints in the backerboard won t line up with the joints in the subfloor. Add more mortar as necessary to fill sunken areas in. Good luck with your project. An additional layer of thinset is then applied to the surface of the backer board and used to set the tiles.

Do a dry run and lay the backerboard down to fully cover the area you plan to tile. After all backer board sheets are in position remove the 16d common nails. The backer board comes in different sizes and you will pick the right one depending on the type of floor you are installing. Its made from cement and sand and is reinforced by fiberglass mats on both sides so it s impervious to water.

So the answer is yes you would need to install a plywood subfloor under the cement backer board before applying the tile. The backerboard should completely cover the subfloor joints. Leave a 1 4 inch gap between the edges of the backer board and the walls to allow for subfloor expansion and contraction. The thickness of the subfloor including the cement backer board should be a minimum of 1 1 8 thick so if you use 1 2 backer board you would need at least 5 8 plywood.

If needed cut the backerboard to fit in small spaces or around obstructions.