How to Retile a Tile Floor

Measure the dimensions of the floor to determine the square footage. Add 10 percent to the square footage to account for errors before purchasing the new tile. Most subfloors are either wood or concrete, and wood subfloors need backer board for tile to adhere to properly. If the floor needs backer board, divide the square footage by 15 -- backer board comes in 3-by-5-foot dimensions -- to determine the amount of 1/2-inch backer board to purchase.

Break the first piece of your existing tile with a hammer. After removing the first piece, use the hammer and a chisel or flat bar to break the rest of the tile free from the substrate. Use a chisel to scrape the substrate free of any thinset, until a smooth surface remains. If there is damaged backer board, remove any damaged backer board with a hammer and flat bar after removing any visible screws. Scrape the substrate clear of any thinset.

Measure, mark and cut enough 1/2-inch backer board with an angle grinder and mason blade to cover the floor. Test-fit the 1/2-inch backer board before setting with thinset. Mix together a slurry of water and thinset -- the consistency of pancake batter -- with a drill and paddle bit. Spread the thinset on the wood subfloor with a 1/4-inch notched trowel. Install the 1/2-inch backer board with screws on every edge every 8 inches over the entire surface. Fasten the screws 3/8 of an inch in from the edges and 2 inches away from the corners. Cover all the seams of the backer board with 2-inch fiberglass mesh tape. Spread thinset evenly over the mesh tape. Allow the thinset to dry overnight.

Determine the center of the room with a tape measure and snap a chalk line for a reference guide. Test-fit the first row of tile. Keep the tile evenly spaced with 1/4-inch or 3/8-inch spacers. Cut the end pieces of tile with a tile wet saw. Temporarily remove the tile.

Mix water and thinset to the consistency of peanut butter and spread the thinset on the floor for the first row of tile with a 3/8-inch notched trowel. Firmly press the tile into place. Clean any excess thinset of with a damp sponge. Spread thinset on the floor for the next row of tile and set the tile into place using the tile spacers to keep the tile evenly spaced. Lay the entire floor using this method. Allow the floor to set overnight.

Clean the floor thoroughly with clean water and a sponge. Mix together water and grout to the consistency of cake mix. Fill in the grout lines with the mixture using a rubber trowel. Wipe away any excess grout with a sponge. Allow the grout to cure for 72 hours before sealing the grout with a sealer.