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