How to Install Cement Backerboard Flooring
Cement backerboards are 3'x5' sheets that get screwed into place much like drywall and then topped with a thin layer of mortar for tile flooring. Backerboards are a much easier method than the traditional mud flooring for tiling jobs and have become a popular choice for do-it-youselfers. Does this Spark an idea?
Things You'll Need
- Tape measure
- Straightedge
- Carbide-tipped cement board knife
- Square notched trowel
- Margin trowel
- Cement backerboard
- Thinset mortar
- Backerboard screws
- Fiberglass tape
Instructions
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1
Place the first sheet of cement backerboard in a corner. Plan the layout so that none of the backerboard joints falls directly over joints in the underlying plywood. Stagger backerboard joints by at least 18 inches so that there is no place where the four corners meet.
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2
Cut sheets of backerboard as necessary by first measuring for the cut and subtracting 1/4", since the cut will be rough and jagged. Mark your line on both ends and then use a straightedge to connect the marks. Cut the backerboard sheet with a carbide-tipped cement board knife by scoring until the cut is about 1/16" deep. Slide a 2x4 under the sheet in line with the scoring and, while holding one side of the sheet, press down on the other so that the board snaps along the cut line. Stand the sheet on its edge and make a pass with the knife to make the final cuts.
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3
Mix a batch of thinset mortar and spread enough for one piece of backerboard on the subfloor using a 1/4" square notched trowel. Carefully position the first sheet in the mortar, leaving approximately 1/4" around the perimeter area next to the wall.
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4
Drive backerboard screws through the board into the subfloor every eight inches. Around the perimeter, screws should be placed every six inches.
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5
Continue to lay sections of thinset mortar and place and screw the backerboard. Leave 1/8" gaps in between sections of backerboard.
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6
Stick a strip of fiberglass mesh tape over each joint. Press into place with a taping trowel.
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7
Using the flat edge of the trowel, spread a thin layer of thinset mortar over the tape. Take care to fill only the groove and not create any high spots. Feather the thinset mortar on each side, and smooth away any lumps or mounds.
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8
Wait 12 hours for the thinset to cure, and then you will be ready to tile.
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Tips & Warnings
If rough edges are on the backerboards after being cut, they can be smoothed with a rasp, a tile stone or the rough finish of a cinder block to smooth out the rough spots so that the sheet can fit appropriately with neighboring sheets.
