Installing New Underlayment

No matter how you finish your floor, it will only be as good as its underlayment -- the supporting layer fastened to the joists. Underlayment provides a smooth, stable surface for the finished floor.

You can lay ceramic tile over hardwood and ceramic floors -- if the surface and subfloor are stable and in good condition. The same is true for uncushioned resilient tile or sheet materials on a wood frame floor. But new ceramic tile over an existing floor will raise the surface by at least 3/4 inch. Removing the existing floor will minimize any change in floor levels and reveal any hidden faults that need repair.

If your underlayment shows signs of rot or is not thick enough to support the finished floor, or if you're working in new construction, you'll have to install new underlayment, typically 3/4-inch exterior plywood. Bring the plywood into the room a few days before installation to acclimate it, which will reduce shrinkage or expansion.

Prestart Checklist

Time
From 30 -- 45 minutes per square yard

Tools
Tape measure, chalkline, circular saw, cordless drill, screwdriver bit

Skills
Measuring and marking, cutting with circular saw, driving fasteners with cordless drill

Prep
Remove existing flooring as necessary

Materials
3/4-inch exterior grade plywood, construction adhesive (optional), galvanized screws