Apparantly modern plywood has something in it which affects the tile cement i know from experience as i put on approx 10m2 of tiles before i discovered that they wouldnt stick to plywood however you can buy sealer which can be painted onto the plywood that makes the tiles stick on ok.
Tile over plywood wall.
While tile can be laid on plywood do not install tile directly onto the plywood subfloor itself.
Center your tile in the bathroom.
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.
The preferred method for tile installations is to use a sheet of underlayment.
There are tiling mats you can cover the plywood with decoupling mats such as ditra you then tile right over that.
You may tile over existing tile painted or unpainted drywall plaster and textured walls.
You should not tile over wallpaper glossy surfaces lead paint or plywood.
If you re not sure if you have lead paint test kits are available.
If possible you should always use concrete board underlayments rather than plywood.
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.
Plywood is not dimensionally stable it can shrink swell and otherwise move around no matter how many screws are holding it in place.
Use intervening layers of two sheets of plywood.
No you can t tile to the plywood directly as wood is prone to warping.
Use your drill to make this job simpler.
Concrete board concrete board also called backer boardcomes in 1 4 and 1 2 thicknesses and is usually sold in 4 x 6 sheets.
It should be fastened to the subfloor using thinset and then screwed down every 10 square.
Shrinking and swelling will crack the grout can pop off tiles etc.
To install the concrete board apply tile adhesive to the back then press it down against the plywood.
When creating a grid pattern start at the center where the lines intersect.
Spread the mastic over a 3 square foot section of your installation area using a notched trowel onto the wall.
Step 4 center.
However tiling over tile can add quite a bit of thickness so make sure your wall can handle the weight.
Use thinset with a higher latex content thinset is the wet base that you first trowel on the plywood to make the tile stick.
There are two materials commonly used for laying ceramic on plywood or osb that are applied before the tile.
For wall installations plywood is overkill beneath the concrete or fiber board which is designed in five eighths inch material for wall settings.