Cement Board Floor Installation
- 1). Vacuum the subfloor to remove any debris.
- 2). Mix a batch of thinset mortar, following the instructions on the packaging.
- 3). Apply a coating of thinset onto the floor in one corner of the room, covering an area big enough for one sheet of cement board. Create ridges in the thinset with the notched edge of a 1/4-inch notched trowel.
- 4). Lay a sheet of cement board onto the thinset, leaving a space of 1/4-inch between the wall and the cement board.
- 5). Apply thinset to the next section of the floor, using the same method. Lay the second cement board onto the thinset, keeping a 1/4-inch gap between the wall and the cement board and an 1/8-inch gap between the two sheets of cement board.
- 6). Continue installing cement boards until you reach the wall. If you need to cut a sheet, measure and mark the cut line, then cut it with a jigsaw with a masonry blade. Wear safety goggles when cutting the cement board.
- 7). Cover the rest of the subfloor with the sheets of cement board, using the same technique. Stagger the sheets in each row so there is no point when the corners of four sheets meet. Cut openings for floor vents or outlets. Drill a hole through the cement board with a masonry-tipped drill bit, then cut the board with the jjigsaw, using the drill hole as the starting point.
- 8). Drive backerboard screws into the perimeter of the sheets every 6 to 8 inches and between 1/2-inch and 2 inches in from the edge of the sheets. Drive the screws into the sheets until the heads are even or just below the surface of the material.
- 9). Apply thinset to the gaps between the sheets with the flat edge of the notched trowel. Smooth the thinset out so it extends 1 1/2 inches on each side of the gap.
- 10
Lay strips of 2-inch vinyl-coated fiberglass tape over the thinset in the seams, pressing the tape into the thinset with the smooth edge of the trowel. - 11
Apply a thin layer of thinset over the tape and smooth it out with the trowel. Don't create any ridges that could affect your tile work.