Before he opened Stenholm Custom Remodeling, in Farmington, Minn., Kevin Stenholm was a tile setter. He continues to do tile work in-house and enjoys tackling complicated tile projects. Kevin’s tips for installing tile:

1. The right tile. Glazed vitreous or impervious tile is best for a shower surround; unglazed tile is suitable for walls or a backsplash. Hardness matters. For ceramic and porcelain tile, grades IV and V are best for a floor. Natural stone is measured on the 10-point Mohs scale of mineral hardness, but a high number doesn’t always indicate that a product is suitable for floors.

2. Sound structure. Backerboard and mortar with metal lath reinforcement aren’t designed to support weight. A subfloor of ¾-inch plywood on joists 16 in­ches on center is the minimum necessary for proper support for a tile floor. Even a small amount of deflection or “bounce” in the floor will cause the grout to crack and eventually will loosen the tile.

3. Surface prep. The surface must be clean and dust-free to ensure proper adhesion of the mortar or adhesive.

4. Mortar coverage. A min­imum of 80% coverage of the mortar or adhesive on the back side of the tiles is essential to keep tiles from popping loose or cracking. Improper coverage can also result in a hollow-sounding tile. Check the coverage by lifting a few tiles after setting them in adhesive.

5. Movement. Always caulk movement joints — don’t use grout. A movement joint lets the area between two substrates flex with temperature changes and structural movement. Create movement joints at wall corners and wall-floor intersections, and between the tile and the surface of a fixture or countertop. Also use movement joints to avoid cracks in floors spanning more than 25 feet. Movement joints are more important on a three-season porch, where temperature fluctuates, than on a concrete basement floor that maintains a constant temperature.

6. Alignment. Misaligned tile edges are called “lippage,” and the result is an uneven surface. With handmade tiles or natural stone, which vary in thickness, using a deeper notched trowel enables you to align the surfaces. If all the tiles are the same thickness, then lippage is likely due to an uneven subfloor. The larger the tile, the flatter the substrate should be. Consider using a self-leveling compound to level the floor, even on a concrete slab, which often looks flat but isn’t.

7. Vapor barrier. A moisture barrier properly installed behind the backerboard prevents prob­lems in a wet area, such as a shower. Use 4- or 6-mil polyethylene sheeting stapled to the studs; overlap vertical seams 6 inches and tape with vapor barrier tape.

8. Good side up. It may sound funny, but it’s easy to install natural stone tiles upside down. Take your time, especially with porous tile such as tumbled travertine.

9. Sealing. For all natural stone products, seal the grout and tile to prevent staining and water penetration. Wait until the grout is cured (usually three days) before sealing.

10. Workmanship. Even a well-designed layout can be ruined by poor cutting, resulting in chipped tiles, crooked grout lines, and a grouting haze left on the tile.

For more tiling know-how, check out Tiling for Contractors in the JLC bookstore.