How to lay tiles on chipboard flooring in bathroom
Overboard with no more ply or similar
OP,
Overboarding is not always needed.
Are the boards in the pic definitely chipboard?
Correctly laid, Chipboard sub-flooring is usually 18mm or 22mm T&G.
The T&G should be very well screwed down to joists & noggins, and can be glued at the T&G joins.
No movement is allowed in joists or sub-flooring.
Your height benchmark for the surface of the tile is the door threshold - or the swing of the door itself.
Consideration must also be given to possibly raising other fixtures in the room eg the WC.
Overboarding is not always needed.
Are the boards in the pic definitely chipboard?
Correctly laid, Chipboard sub-flooring is usually 18mm or 22mm T&G.
The T&G should be very well screwed down to joists & noggins, and can be glued at the T&G joins.
No movement is allowed in joists or sub-flooring.
Your height benchmark for the surface of the tile is the door threshold - or the swing of the door itself.
Consideration must also be given to possibly raising other fixtures in the room eg the WC.