Is 3/4" OSB, 1/2" plywood and 1/4" cement board adequate for ceramic tile?

Question

I’m replacing a sink base cabinet that’s seen damage through the 3/4 ply underlayment, but the 3/4 OSB subfloor underneath might still be in good shape due to a vapor barrier sandwiched in between. We’re planning on removing the old cabinet and making way for an ADA compliant one so my dad’s wheelchair can access the sink.

The work I’m planning is replacing the damaged 3/4 plywood, installing 1/4" Hardie backer and some tile.

Can I replace the 3/4 plywood underlayment with 1/2 ply since there is already a 3/4 OSB subfloor beneath?

Answer 1

Replacing the 3/4 plywood with 1/2 ply and 1/4 hardie backer, should be ok.

An added thought: Consider LVP flooring instead of tile.

It is easier for a wheel chair to roll over, as there are no grout lines.

Most all are waterproof.

Should your father drop something heavy it will not chip.

It is easier to clean, ( just damp mop) and again, has no grout lines that need scrubbing.

And finally... if there is any movement in the subfloor, there is nothing to crack.