Installing Cement Backerboard
You may be tempted to rush ahead and get to the fun part ─ laying the tiles ─ but try to resist the urge. Unless you prepare the surface under the tiles properly, you'll end up having to retile a lot sooner than you would like. Tiles need a smooth, flat, rigid surface to sit on. Plywood is sometimes used, but cement backerboard is generally considered a better choice. Backerboard is essentially a thin layer of concrete with fibreglass mesh on both sides. It was designed specifically as a setting surface for tile. Backerboard comes in a range of sizes: 3- by 5-foot sheets are most common for floors. Over a 5/8-inch subfloor, use 1/2-inch-thick sheets.
- Snap a Grid of Chalk Lines
- Place Backerboard on Adhesive
- Drive in Backerboard Screws
- Fill the Joints with Adhesive
- Cover Joints with 2" Fibreglass Tape
Snap a Grid of Chalk Lines
Snap a grid of chalk lines on the floor to mark the dimensions of the sheets. Plan so that joints in the backerboard won’t line up with joints in the subfloor. With the smooth side of a ¼-inch notched trowel, spread enough adhesive for one sheet. Ridge the adhesive with the notched side of the trowel.
Place Backerboard on Adhesive
While the adhesive is still wet, place a sheet of backerboard into it. Leave a ¼-inch gap between the backerboard and the wall and a 1/8-inch gap between the backerboard sheets. Position the sheets so that you don’t have four corners meeting.
Drive in Backerboard Screws
After you've positioned each sheet, drive backerboard screws into it every 8 inches. Around the perimeter, position the screws at least 1/2 inch, but no more than 2 inches from the edge.
Fill the Joints with Adhesive
With a margin trowel or the flat side of your notched trowel, fill the joints with adhesive, smoothing it so it extends about 1 1/2 inches on each side of the joint. The extra adhesive makes it easier to bed the tape.
Cover Joints with 2" Fibreglass Tape
Cover the adhesive-filled joints with 2-inch vinyl-coated fibreglass tape, pushing it firmly into the adhesive. You can cut the tape to length with the thin side of your trowel. When the tape is embedded, scrape off any excess adhesive from both sides.
Cover Tape with Adhesive
Cover each length of tape with a thin layer of adhesive. Spread the adhesive with the flat side of your trowel and feather the edges. You want the transition from board to board to be as smooth as possible.
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Skill Level: Intermediate
Time: 3 hours
Due to differing conditions, tools, and individual skills, The Home Depot® assumes no responsibility for any damages, injuries suffered, or losses incurred as a result of attempting to replicate any of the home improvement ideas portrayed in this website Before beginning any home improvement project, review it thoroughly to ensure you or your contractor can finish the project and if any doubts or questions remain, consult local experts or authorities. Because codes and regulations vary greatly, you always should check with authorities to ensure that your project complies with all applicable local codes and regulations. Always read and observe all of the safety precautions provided by any tool or equipment manufacturer, and follow all accepted safety procedures.
- 2" vinyl-coated tape
- 1/4-inch trowel
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