Do I Need A Sub Floor For Cement Board

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.

Do i need a sub floor for cement board.

And then once the cement board is down and it s screwed in do i have to put some type of mesh tape to put the boards together and then mortar the tape. Cement board a sheet of lightweight concrete and fiberglass mesh should be laid over top of the subfloor for any tile project. It strengthens the floor removes bounce and gives the tile a. So first of all if you re going to put down durock which is sort of that cement board that you re describing generally that s screwed down.

Apply a supporting bed of mortar or modified thinset to subfloor using a 1 4 square notched trowel. They skipped putting down the thin set under the cement board even though the installation instruction specify that it is required. The primary benefit of cement board is that it doesn t break down or expand or warp if it gets wet. It depends on the sub surface if it is a concrete slab then no but if it is a plywood decking yes.

If it is a planked floor then y. If it is vinyl tile glued over a concrete slab you can clean the tile and adhere the tile directly to the vinyl. Make sure the joists are wide enough for the span and spaced on 16 centers to provide a sturdy floor with no bounce. Embed the cement board in latex modified thin set mortar the main reason for using thin set between the cement board and the subfloor isn t as much for bonding as it is for even void free cement board support throughout the floor.

I plan on thinsetting and screwing cement board to the subfloor then redgard then thin set and tile. 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. So you would screw that down to. Precut and fit all the cement board and then lift all of the cement boards out.

Cement backer board is more dimensionally stable than plywood and forms a better bond with the thin set adhesive used to glue the tile down. Cement board also provides an additional layer over a plywood or particleboard subfloor adding stiffness to the tile. I need to match the height of the existing tile in the bathroom. This is a distinct advantage over plywood and drywall.

Would this calculation get me to the right height compressed thin set on top of sub floor 1 8 cement board 1 2 compressed thin set on top of cement board 1 8. This means that tile applied to cement backer board resists cracking and popping loose better than tile applied to a plywood subfloor alone.