So I really have three options: 1) The correct way - rip up the NPM which will probably also destroy the floorboards. Fix/strengthen the joists so no deflection and lay 12/18mm ply floor, overboard with NPM or Hardiebacker. Tile. Expensive, disruptive and will make me cry.
2) The risky adhesive option - bearing in mind that the deflection is minimal a very flexible adhesive might resolve the problem. Only time will tell. 2 or 3 tiles would be affected. One commenter suggests he doesn't think i have a deflection problem in such a small room.
3) The raised floor option - Ply or hardiebacker. Adds 2 cm to the height of the floor. Will it definitely stop bounce after all that effort?
I hope the answer comes to me in the morning...night all. Thanks for weighing in.
Do you have a self levelling laser?
If you do then sit it in the middle of the room & mark it on the wall, stand beside it & get someone to mark the wall again & that will show you exactly how much movement you have in your floor.
I think you may be over thinking this floor too much as you always do get slight movement in a floor, it's trying to assess how much movement you do have, it's all well & good us sitting here trying to offer advise but we can't see the floor so it's a bit of a guessing game.