Before laying tile in the bathroom, it is important to prepare the floor by removing the old flooring and inspecting the subfloor for damage. Laying tile in a bathroom requires a level surface that is free from cracks and holes. Preparing the bathroom floor for tile ensures the tile will last longer and prevents possible damage to the underlay. Using a cement backer board provides an added layer of protection, making the floor sturdier and less prone to damage.
Turn off the water supply to the toilet and flush the tank. Remove the toilet by unscrewing and removing the two nuts on each side, and then pulling it straight up. Set the toilet aside and not on the floor you're working on. Scrape the wax ring from the floor and dispose of it.
Remove the old flooring material. If it is carpet, vinyl or linoleum, pull it up and use a scraper to remove any remaining glue. Sweep and vacuum the floor, removing all debris.
Take out any nails, staples or screws remaining in the sub flooring, using pliers and a small pry bar to avoid damaging the subfloor. Use caulking or crack filler to fill any holes or cracks in the floor. If the subfloor shows sings of damage, such as from water, replace the area before continuing.
Cover the floor with a cement backer board material purchased from your local builder supply or hardware store. Backer board protects your sub flooring from future water damage by adding a moisture barrier.
Measure the bathroom floor and cut the backer board to fit the room. Use a framing square to score your cut and use a carbide blade cutter to cut the backer board. Lay the backer board over the floor and screw it into the floor joists about every eight inches. Leave a space between the boards and fill it in with thinset mortar, using a taping knife.
Use fibreglass joint tape to cover the seams and apply another layer of thinset mortar. Begin laying the tile on your bathroom floor when the mortar sets.
Make sure your subfloor is sturdy. If not, use plywood to make the foundation acceptable for tile flooring.