Uneven bathroom floorboards & laying ceramic tiles

[hampshire_rob]

Before I start, great forum guys/girls.

Here's my problem, I recently extended my bathroom by knocking down a stud wall and extending further into a bedroom.

As expected, the floor joist holding the stud was reinforced (3 joists together). The problem is that it was 1/2 inch higher than all of the others on either side.

New boards were layed over leaving a slight (invisible) peak about 1/3 of the way into the room.

I'm about to pick floor tiles but I'm nervous about getting large ones due to the possibility of cracking near the peak.

Will I be OK if I get very small mosaic tiles? say 1 inch square?

Also, Will they adhere directly to a 1/2 inch marine ply under boarding I intend to screw to the floorboards?

 

[gcol]

Yes you'll be fine with 1" mosaics - no cracking. Personally, I wouldn't entertain mosaics for floors. Generally (in bathrooms) I recommend 13" sq tiles unless you have a very large floor space.
You could probably ramp the tiles up (and down) that slope, but I'd recommend porcelain tiles cause they won't crak as easy.
Is it out of the question that you can level out the joist?
Goes without saying that you need flexible adhesive and grout. (marine ply is fine - screw it down every 6-8")

 

[hampshire_rob]

Thanks for the advice.

With respect to the idea of ramping up could I lay the adhesive thicker in the lower parts and thinner in the high point to reduce the 1/2 inch height difference even more (to say 1/4 inch).

I'm loathed to take the floor up as the bath is plumbed into place and the boards are fully nailed down (with new plaster overlapping at the edges).

 

[gcol]

You could but you're making the tiling job more difficult than it needs to be. Also, flexible adhesive is about 2.5 times for expensive that non-flexible so you don't really want to be wasting it in packing the tiles up. You really either want to drop the high part or raise the rest of the floor to that level.

 

[simon_t]

Does it come to a point like a pitched roof, or is it a step? If it's a step you could just lay a thinner panel on one side to take up the difference.

simon