How do I tile on wooden bathroom floor?

[405 TD Estate]

I'm a bit concerned the floor may move a bit and so the tiles may break or may not be waterproof.

How do you do this?

Do you need to prepare the wooden floor first i.e. make it perfectly flat?

[Paul Giverin]

In message , 405 TD Estate writes

I recently laid tiles on a bathroom floor where the base was chipboard. I screwed sheets of marine ply to the chipboard and laid the tiles using a flexible adhesive (Bal Fastflex). Six months on and its completely solid... no sign of cracking or movement, touch wood.

[The Natural Philosopher]

Not flat, no, but extra stable, and use a thick bed of flexible tile adhesive.

If its floor BOARDS remove and fit 18mm ply, or simply ply over the top.

If the floor is 'bouncy' you are in trouble. You may need to remove the floor and beef up the joists, and herringbone them as well.

I was deadd worried about one bathroom, but by the time I had build a shower wall ad bath enclosure out of ply, screwed to floor and walls..it wasn't bouncy anymore!

It had a 2" drop at one end as well.I simply screwed and nailed bits of scrap to fill up the worst, and used odd bits of cement left over from each mix to fill the hollows.

Its all just fine and you would never guess what is under the tiles :-)

[The Natural Philosopher]

I laid mine straight on the chip. No problems. Its boardds that need covering frankly.

The secret is stability and a THICK base of flexible cement. 6mm at least. Oh, and NO LEAKS and NO DODGY GROUT. If water collects under the tiles on chip, it will swell and crack them off. I did one bathroom with a temporary layer of thin tiles and thin cement and a loo drip did exactly that. I stripped the lot off, let the chip dry properly after fixing the leak, and put it down PROPERLY with tiles up the walls as well and really grouted the arse off it. No problems now.