Installing Ceramic Tile

Whether you have chosen thinset mortar or organic mastic, bring it into the room to acclimate it to normal room temperatures--ideally between 65 and 75 degrees Fahrenheit. Mix thinset with water that is clean enough to drink, and clean out the bucket after each mix; mortar and adhesive residue can cause a new batch to cure prematurely.

Adding the powder to the water a little at a time reduces airborne mortar dust and makes mixing easier. Let the mixture set for 10 minutes so the water will penetrate any lumps. Then mix again to remove lumps. To test the consistency, load a trowel with mortar and hold it upside down. If the mortar falls off the trowel easily, add more dry powder and remix. The ideal consistency is about as thick as peanut butter. Clean the bed before troweling.

The size of the notches in the trowel you use will depend on the thickness of the tile. The depth of the notch, and therefore the ridge it forms in the adhesive, should be about two-thirds the tile thickness.

Use 1/16- to 1/8-inch V-notched trowels for thin tiles, such as glazed wall tiles. For 6- to 8-inch floor tiles, use a 1/4- to 3/8-inch square-notched trowel; for large tiles (more than 12 inches), use a deep (1/2-inch) square-notched trowel.

Combing adhesive so it forms the right-size ridges requires that you hold the trowel at about a 45-degree angle and keep the edges of the trowel in constant contact with the substrate. If you have trouble making 1/4-inch ridges with a 1/4-inch trowel, switch to a 3/8-inch notch and hold the trowel at a slightly lower angle.

Properly applied thinset forms ridges that compress to cover the entire back of the tile when it is embedded. If thinset is applied too wet, it will not hold these ridges. A dry thinset application will not compress and will result in the tile adhering to the top of the ridges only.

Test a thinset mixture occasionally by pulling up a tile and examining the back. If the thinset completely covers the surface, the mixture is correct, as shown above.

When laying loose tiles (not sheet-mounted), use plastic spacers to keep the tiles the proper width apart.

Insert spacers vertically in the joint after you set each successive tile. That way the tile will be in the correct placement after it is embedded in the mortar. Once you reach a point where tiles form corners, flip the spacer down into the corner. Pull the spacers before grouting, even if the manufacturer's instructions indicate that you can leave them in place. Spacers may show through the grout.

Tiles with irregular edges, such as saltillo and handmade pavers, may be difficult to keep straight, and spacers will not help. To keep such tiles aligned, make your layout grids small -- a nine-tile (three-by-three) layout works well.

Trowel adhesive one grid at a time and set the tiles in place. Adjust the tiles until the appearance of the joints is consistent, and expect to make a few compromises.

Mosaic sheets require special care when you are setting them. Their numerous edges can tip within the sheet or rise higher than the adjoining sheet. To keep them flat, use a grout float to gently tap them level both within the field of the sheet and at the edges. Use this same technique when aligning them to the contour of a drain recess on a shower floor.

When setting marble or translucent stone, use white thinset; colored mortar may show through. Marble, granite, and travertine tiles look best with thin 1/16-inch grout joints.

Stone tiles are more brittle than ceramic tile and therefore more prone to cracking. Make sure the setting bed is stable and flat. Damp-sponge any dust off the back of the tiles, if necessary. Apply the mortar recommended by the distributor or manufacturer of the stone.

Check each tile for level with a straightedge, pulling up and back-buttering tiles that are low. Make sure the edges of one tile are not higher than another.