Floor Tile Backer Board Or Subfloor

Floor tiles should be installed over smooth flat surfaces.

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. The backerboard should completely cover the subfloor joints. 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. After all backer board sheets are in position remove the 16d common nails.

Lay the backer board according to the manufacturer s instructions. 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. To achieve the ideal flat surface most contractors rely on the backer board cement backer board is a thin layer of concrete designed to be setting surface upon which tile can be installed. Spread the mortar to about 3 16 thickness.

Using a notched trowel apply a leveling bed of thinset mortar over the subfloor and embed the backer board sheets into the adhesive. 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. Also if your subfloor runs east to west lay your backer boards in the opposite direction north to south. Good luck with your project.

Its made from cement and sand and is reinforced by fiberglass mats on both sides so it s impervious to water. First changes in humidity make solid wood shrink swell and cup more than plywood. Add more mortar as necessary to fill sunken areas in. 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.

Plan so the joints in the backerboard won t line up with the joints in the subfloor. If needed cut the backerboard to fit in small spaces or around obstructions. The backer board comes in different sizes and you will pick the right one depending on the type of floor you are installing. Second the strength of wood boards isn t always consistent.

Cement board is the most durable trouble free tile backer for tub surrounds showers floors and all other wet areas. Leave a 1 4 inch gap between the edges of the backer board and the walls to allow for subfloor expansion and contraction. An additional layer of thinset is then applied to the surface of the backer board and used to set the tiles. The backer board is then secured with screws to the subfloor beneath.

So the answer is yes you would need to install a plywood subfloor under the cement backer board before applying the tile.