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.
Ceramic tile on wood subfloor.
Fill seams in the subfloor with caulk.
This may be a problem if it creates a noticeable offset to adjoining floor surfaces such as between a ceramic tile kitchen and wood floor dining room.
First changes in humidity make solid wood shrink swell and cup more than plywood.
This prevents the floor from sagging and helps to increase its overall life.
It s designed to hold up to the pressure of foot traffic.
However there is a new product by schluter called the ditra system.
Check for dips in the floor by sliding a 4 foot to 6 foot straight edge in different directions all around the room.
This bounce will crack the tiles.
Most ceramic tiles have very little tensile strength.
Installing over wood.
Thin set was used instead of glue or adhesive.
It s important to first lay down a layer of subfloor plywood.
It is an orange colored membrane designed as a backer for tile.
It can also require that doors be trimmed and trim moldings reinstalled to accommodate the height changes.
An extra layer of ceramic tile adds substantial thickness to the flooring layer.
Pourable self leveling products help to flatten and level a wood subfloor or a concrete slab before the tile is installed.
The dry product is mixed with water to a liquid consistency and poured on.
Use thinset with a higher latex content thinset is the wet base that you first trowel on the plywood to make the tile stick.
Underlayment plywood is a different material than that used for other applications such as deck panel plywood.
Installing a top layer of hardwood tiles or linoleum on your floor is only part of the job.
First of all tile definitely should not be put down over a wood sub floor.
More specifically let me see if i can answer some concerns.
Some wood floor systems when designed to minimum standards have too much bounce.
While tile can be laid on plywood do not install tile directly onto the plywood subfloor itself.
Floor joists are basically wood i beams.
In other words if you try to bend or stretch a tile it will crack.
Now the entire flooring of ceramic tiles needs to be torn out and replaced.
Second the strength of wood boards isn t always consistent.
The floor tiles became loose cracked and ugly looking over about 2 decades of use.
Prepare a wood subfloor for tile a successful tile installation project requires a level surface.
We have our large kitchen and hallway that was originally covered by 12 x 12 ceramic tiles on top of 3 8th inch plywood.
Use intervening layers of two sheets of plywood.