I am tiling a small half-bath with an area roughly a little over 4'x8'
with ceramic tile. The old floor was plywood that was screwed and
nailed to the subfloor. There is an area 51" by 13" where there is no
plywood, just old wood flooring. The other wood flooring had been
taken out and replaced with the plywood. The floor is solid with no
bounce when jumped on. There is an elevation difference of less than
1/8".
Questions: What can be done about the elevation difference or since
it is so small, is it really a problem? Do I need to use backerboard
or can I use mastic directly over the wood? If I use backerboard, can
I just glue it for that small of a space?