How thick does subfloor need to be for ceramic tile?
Accordingly, what kind of subfloor is needed for ceramic tile?
The subfloor under the tile should be at least 1 1/8″ thick, with a minimum of 5/8″ thick exterior grade plywood topped by 1/2″ cement backer board.
Similarly, how thick should cement board be under tile floor? Cement-fiber, or similarly reinforced, backer board comes in standard 1/4 inch and 1/2 inch thicknesses. If you're installing backer board over an existing subfloor, 1/4 inch is sufficient. If you're installing backer board in new construction, attaching it directly to floor joists, opt for 1/2 inch sheets.
Additionally, can you lay tile directly on subfloor?
While you can lay tile directly over a concrete slab using thin-set adhesive, don't make the mistake of applying tile directly to a plywood subfloor. No matter how firm the subfloor; the plywood will expand and contract at a different rate as the tile, causing cracks to develop in the grout lines or tiles over time.
What is the best underlayment for tile?
Exterior plywood is an acceptable underlayment for tile and is preferred to interior-grade plywoods because the bonding adhesives used are waterproof. If water seeps through the tile installation to the underlayment, it will not cause the wood to swell, as happens with interior-grade plywood.