According to backer board manufacturers and tile setters installing backer board directly over an old solid wood subfloor is risky for a couple of reasons.
Tile on wood subfloor.
Use the right.
If the subfloor is 5 8 or 3 4 you can probably apply tile directly to it with no problem.
Sandynovember 14 2015 at 5 31 pm.
Make sure grout joints are completely filled.
Follow the directions on the packaging to properly mix the thin set mortar.
The best method is to refasten the subfloor then add a layer of plywood.
With a trowel scoop out and spread enough mortar on.
Using a grout float held at a 45 angle spread grout firmly into tile joints.
Use a large bucket and.
Allow grout to set for 10 20 minutes then lightly clean tile and shape grout joints with a damp sponge.
Install 1 4 inch cork by thin setting it to the concrete pad then installing the heating system by fastening it to.
It is a good idea to put half inch plywood underlay to strengthen the floor before using modified thin set to put the tile directly on wood.
Use thinset with a higher latex content.
While tile can be laid on plywood do not install tile directly onto.
Use a polymer modified thin set a type of mortar to attach the backer board to the subfloor.
First changes in humidity make solid wood shrink swell and cup more than plywood.
Using cool clean water mix the grout to a lump free non pourable consistency.
Lay down a vapour barrier overtop the concrete pad then fasten 3 4 inch plywood using a ramset to the concrete pad.
A couple options considered are.