How to Secure Concrete Boards to a Concrete Wall
Concrete boards, commonly called backer boards, install over concrete and act as an insulator between the concrete walls and materials such as tile, vinyl or linoleum. These boards have a concrete core and on the outside, they have fibers to create a strong moisture resistant board. Installing backer board onto a concrete wall differs slightly from installing backer board onto wood walls with studs. Does this Spark an idea?
Things You'll Need
- Tape measure
- Furring strips
- Drill
- Hammer drill
- Masonry bit
- Tapcons
- Screwdriver
- Carbide cutter
- Galvanized screws
- Tile adhesive
- Taping knife
- Fiberglass tape
- Sanding block
- Level
Instructions
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1
Measure the width and the height of the wall where you need to install the backer board. Cut a two-by-three inch furring strip for every four feet and one strip for each end of the wall. A furring strip is a piece of wood used in place of a standard wall stud. They are thin pieces of wood that allow for small air gaps.
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2
Drill 1/4-inch pilot holes in each furring strip approximately every 12 inches.
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3
Place the first furring strip in the left side of the wall and hold it n place. Use the holes in the furring strip as locator holes for drilling pilot holes into the concrete. Use a hammer drill and a masonry bit approximately half the size of the Tapcon you are using and drill pilot holes into the concrete. Secure the furring strips to the concrete wall with Tapcon screws and a screwdriver. A Tapcon screw is a specialty screw designed for concrete.
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4
Measure four feet from the center of the first furring strip and secure the next furring strip to the wall in the same manner as the first. Duplicate the process until you install all four of the furring strips. The use of furring strips adds an air gap between the concrete wall and the backer board to allow for airflow.
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5
Cut the backer board to size just as you would drywall. Score the surface of the backer board with a carbide cutting tool and then bend the board along the scribed line to break it.
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6
Place the first piece of backer board in the bottom left corner of the wall and secure it to the wall with galvanized screws and a screwdriver.
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Place the next board approximately 1/8-inch away from the first and secure it to the wall. Secure each piece across the bottom of the wall leaving a 1/8-inch gap between each board. Duplicate the process with each subsequent row as you work your way up the wall. Gaps allow for moisture expansion. If you butt the boards together when they expand they will push together and could cause any tile glued to the boards to crack.
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Fill in each joint with tile adhesive with a taping knife. Place fiberglass backer board tape over each joint and cover the tape with more tile adhesive. Allow the adhesive time to dry before sanding. If the seams are not flat with the backer board, add more adhesive.
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9
Sand the adhesive joints with a square sanding block. The edges of the backer board are tapered just like drywall. Once you sand the surface of the adhesive joints flat, you will have a flat wall of backer board. Place a level over the joints. If you see any gaps between the adhesive joints and the surface of the level, add more adhesive and repeat the sanding process.
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