Ceramic tile to wood and concrete substrate

[TerryM]

John,
I'm new to tiling and have a customer who has removed an old fireplace and hearth and wishes to fill the recess left with ceramic tiles [7" square x 5/16" thk.]. The area is approx. 6 ft x 6 ft and sits approx. 3/4" below the remaining floor [3/4" hardwood flooring]. The substrate is made up of approx. 25% wood underflooring and 75% concrete.

Since I need to keep the top of the tiles level with the top of the surrounding wooden floor, I have approx. only 7/16" of height to play with. What do I use to ensure a solid job when trying to tile over the mix of wood and concrete ?. The wood and concrete subfloor is basically the same elevation as each other.

Regards

TerryM.

[bbcamp]

Set backerboard over the plywood, then screed thinset on the concrete to match the height. Install an antifracture membrane across the joint, or plan a soft joint in the tile over the joint.