Tiling on wooden bathroom floor

Can you please help? im going to tile my bathroom floor and was going to do it straight onto the floorboards which seem in good condition. I have been told that it is ok to tile on to floor boards as long as it is secure and level as well as using flexible adhesive. Other people have said (and noticed some on this forum) that you need to put WBP plywood down. i would just like to know the pros and cons of both and what is the best way to go about it. Cheers for your time

WBP is mainly for areas that will get a lot of water (shower area) so its not necessarily needed elsewhere, but you probably want to lay a thin sheet to give yourself an even surface to tile to.

Boarding:
Pros
Your tiles stay stuck down.
Give a nice flat surface to tile on.

Cons
Extra cost and time.
Floor is a little higher.


Not boarding:
Pros
You don't need to spend time and money boarding

Cons
The grout will crack and the tiles may loosen.

you have to board, 100% or tiles will come up, or just crack.

minimum ply depth 15mm,

or you can use 6mm hardie backer tiling boards, which are stronger, and waterproof.

http://www.pureadhesion.co.uk/category/37/hardi-backer-boards

you tiles will definitely crack if you do not reinforce your floor, seen it hundreds of times

Hope this helps