There are two materials commonly used for laying ceramic on plywood or osb that are applied before the tile.
Tile over plywood wall.
However tiling over tile can add quite a bit of thickness so make sure your wall can handle the weight.
You should not tile over wallpaper glossy surfaces lead paint or plywood.
Step 4 center.
Concrete board concrete board also called backer boardcomes in 1 4 and 1 2 thicknesses and is usually sold in 4 x 6 sheets.
Center your tile in the bathroom.
No you can t tile to the plywood directly as wood is prone to warping.
When creating a grid pattern start at the center where the lines intersect.
The preferred method for tile installations is to use a sheet of underlayment.
While tile can be laid on plywood do not install tile directly onto the plywood subfloor itself.
Use thinset with a higher latex content thinset is the wet base that you first trowel on the plywood to make the tile stick.
Either backerboard or concrete board is fine but i d recommend backerboard if it s for the wall as it s lighter it s also easier to.
You may tile over existing tile painted or unpainted drywall plaster and textured walls.
If possible you should always use concrete board underlayments rather than plywood.
It should be fastened to the subfloor using thinset and then screwed down every 10 square.
Use intervening layers of two sheets of plywood.
Use your drill to make this job simpler.
If you re not sure if you have lead paint test kits are available.
If you put tile directly on top of plywood it will chip and break.
To install the concrete board apply tile adhesive to the back then press it down against the plywood.
Spread the mastic over a 3 square foot section of your installation area using a notched trowel onto the wall.
Clean and heavily score area to where tiles are to be fixed it sounds like the adhesive does not have a rough surface in which to secure itself to.
For wall installations plywood is overkill beneath the concrete or fiber board which is designed in five eighths inch material for wall settings.
Then you want to install screws into the concrete board in each of the holes.
To be sure maybe drill up to 6 evenly spread out holes in the plywood at least 4mm deep or straight through in the areas to be tiled so the adhesive sinks into the holes and hardens hence creating a stronger fix.
Shrinking and swelling will crack the grout can pop off tiles etc.