Tile Installation Guide: From Substrate to Grout
Step-by-step guide to proper tile installation — substrate requirements, layout planning, setting, and grouting for lasting results.
The Substrate: Where Most Tile Failures Originate
Tile is rigid and fails when the surface it's bonded to flexes. The most critical step in tile installation is ensuring a solid, deflection-resistant substrate:
- Floor tile: Concrete, cement board over subfloor, or uncoupling membrane (Schluter DITRA) over subfloor. Subfloor deflection must meet L/360 standard for tile.
- Wall tile (dry areas): Cement board, tile backer board, or moisture-resistant drywall for light-duty applications.
- Shower walls: Cement board + waterproofing membrane OR Schluter Kerdi board. Never use standard drywall in wet areas — it's a mold disaster waiting to happen.
Layout Planning
Always dry-lay your tile before setting to plan the layout:
- Find the center of the room and snap chalk lines
- Avoid cuts smaller than half a tile at visible edges
- Visualize the pattern with full tiles before committing to adhesive
- Account for expansion joints at walls and transitions
Thinset Selection
Use modified thinset (polymer-modified Portland cement) for most applications. Unmodified thinset is for specific situations (with membranes that require it). Large format tile (12×24" and above) requires large/heavy tile thinset for proper coverage. Tile coverage should be 95% for wet areas, 80% for dry areas minimum.
Grouting
Wait 24–48 hours after setting before grouting. Sanded grout for joints 1/8" and wider; unsanded for narrower joints. Mix to peanut butter consistency. Apply diagonally across joints. Remove haze before it hardens. Seal grout after full cure (2–4 weeks) for non-epoxy grouts in high-traffic or wet areas.