how to prep difficult floor before tiling

[Boogi11]

Hi all, i have a problem and need some advice, i want to tile my bathroom floor,(upstairs), my intention wall to pull up the 1950's 20mm tongue and groove floor boards and replace with 18 or 25mm wbp ply, unfortunatley at the weekend, i discovered that one of the walls is acutally built on the floor boards so i cant take them up? (non supporting)
now the floor boards are solid and dont move, a little creaking but no movement. my father says i should tile over the boards as they are, i thing putting down some 4mm wbp ply over the top and tiling on this would be better, regardless of what option i choose i will seal the wood with a proper sealant, and use a very good quality flexible adhesive.
my concern is that the thicker the wood put on top of the floor boards, the higer the step will be into my hall

any thoughts or suggestions??

regards

 

[tpt]

overboarding with anything less than 12mm ply is a waste of time and money.

Personally i think your best bet is a backer board like no more ply. its a concrete baseboard at 6mm thick.

have a look at this
http://www.tradepricetiles.co.uk/blog/post/view/identifier/tiling-a-wooden-floor-yes-you-can/

but theres loads of info on this forum along the same lines.

 

[Karis]

Don’t be tempted to tile straight onto the boards, it’s most likely be doomed to failure eve using adhesive that’s supposed to be suitable. Overboard min 12mm WBP ply, acrylic seal the under side & edges but do not prime/seal the tile face unless the adhesive manufacturer recommends it. Use additional screws to ensure the floorboards are well secure & screw fix the ply every 150mm, alternatively use a decent tile backer board. Use only quality trade tiling materials suitable for your tiles & tile base, avoid cheap DIY products, they are mostly crap.