How to Lay Tile: DIY Floor Tile Installation

Mix the unmodified thinset. You'll know it's the right consistency when you can draw your trowel through and the ridges just stay standing up. Work one section at a time so the thinset doesn’t dry before you can install the membrane. Spread the thinset onto the floor with the smooth side of the trowel, covering the whole area evenly. Then use the notched side of the trowel to comb the mortar.

Roll the membrane out and press it down into the thinset using a float. Continue working in sections, applying mortar and then membrane.

To waterproof the seams, use waterproofing tape. Spread some thinset onto the membrane and embed the tape into it with your trowel, making sure you have at least a 2-inch overlap on each seam. Cover the seams between the membrane sections and the seams along the walls. If your bathroom has finished walls, you can seal along the walls with caulk or a sealant designed for your membrane instead of the tape.

Next, mark reference lines for the tile. Start by measuring two opposite walls and snapping a chalk line between the center points. Then do the same for the remaining walls. This will give you a starting point. You can spray hair spray on the chalk to help it stay on the membrane.

Dry fit the tile to check your layout, and use tile spacers to make sure the expansion gaps are correct. Leave a 1/4-inch gap along the outside edges for expansion. Mix tile from different boxes to help keep the color consistent throughout the room. If you find you have small pieces of tile on one end, you can slide the layout to one side to give your edge tile more width. Remember to mark new reference lines if you shift the layout.

Mix more unmodified thinset to a peanut butter consistency. Start at the center and spread the mortar evenly, making sure you fill the cavities in the membrane. As you did before, work a section at a time to keep the thinset from drying out before you can lay the tile. Comb the mortar at a 45-degree angle with the notched edge of the trowel.

Lay down the first tile on the reference line in the center of the room, twisting it slightly while pushing down to make sure you're getting full adhesion. Install tile along your reference line, placing spacers between each tile. Every couple of tile, pull one up to make sure there's full contact with the thinset. If there's not, back-butter the tile — apply mortar to the back of the tile — to get more coverage.

Use a wet sponge to wipe off any thinset on the tile surface. Occasionally check for high spots with a long level, and gently use a rubber mallet to even them out. Remember to leave the 1/4-inch gap at the edge of the room. You'll also need to leave a 1/4-inch gap around any pipes.

When you need to cut tile, a tile cutter works for simple cuts. You can cut curves with a handheld tile nipper, and a tile hole saw is best for holes. If you're going to be doing a lot of cuts, you may want to use a wet tile saw, which will make short work of the cutting.

Once the grout is in, you should typically wait 72 hours to walk on the floor, but check your manufacturer’s recommendations for specifics. You can use a grout haze remover to remove any haze left on the tile surface.

Apply silicone sealant to the expansion gaps. After three weeks, you'll need to protect the surface by sealing the grout. Install your baseboards and quarter-round moulding. Install transition strips as needed to cover flooring seams when going from one room to another, especially from tile to another type of flooring.