bathroom flooring tile over wood floor

[Tarek Soliman]

Hi BP 

I am trying to install bathroom floor tile, it has very old sticky tiles 2 layers on the top of ecah other, and the bottom is the original wood floor. 

what would be the best way to install the tile?

should I use 1/4' hardibacker, which mostly after installing the tile would be higher than the current original floor. 

keep in mind I have the bathroom cabinet and the bathtub already there. 

what should  cover the bathroom original wood floor properly in order to install the tile.  

Thank you