tiling bathroom floor

[Burnz0]

Hi All. Im in the process of renovating my house and one of the many things that needs doing is the bathroom. I plan on tiling it throughout - floors and walls and have got a few questions on layout and the actual tiling methodology.

firstly, do i need to do anything about supporting the current floor. It's floorboards attached to joists at 40cm (i think). The boards are fairly flat and most look in decent condition - although they have been chopped up a fair bit to make way for the plumbing and they're not particularly closely packed together unlike the rest of the boards in the house.
I've heard i should put down some depth of plywood and then some special tiling board? - both of which im fine with except for the fact that ill be adding on a lot of height and thus creating a big step up into an already small bathroom. I've also read that i could replace the existing boards so as to reduce the level, the problem being that one of the walls is supported by the boards only (the wall underneath is about 20cm off - apparently quite acceptable practice in 1910-20s houses!) so if i rip these out ill be creating a world of problems.
Finally, do i need to noggin(?) the joists - if so how do i do this and will the noggins not interfere with any pipes that are placed between the joists?

the other question was more of a design/aesthetic type - im planning on going for a black and white colour scheme to keep it simple - black floor, maybe a black border round the bottom and then white tiles to mid wall height - possibly with another black border. I'm having a shower installed over the bath so will need to carry the tiles up further at this point - is there a rule for where you should go from - as in, the whole lenght of the bath, 1metre or so etc. If i do the whole length of the bath to ceiling height i'll only be left with about 1/2 metre at the end of the bath to the front wall so this may look odd so i'd prefer just tiling part of it. I'm also toying with the idea of doing the ceiling height section of tiling in a different colour but can't visualise how i should do this - from mid-wall to ceiling or from the bath level all the way to ceiling just for the "shower" cubicle section

if it helps - ill add a picture when i next get down to the house?
any thoughts appreciated as always!

[warmadmax]

pictures always paint a thousand words so when you can that'd be a great help for the guys to advise

from my readings, the problem with tiling onto wooden floors is the fact they can move,
not a problem with most floor coverings as they are flexible (lino, vinyl, carpet) where as tiles aren't.

if the wooden floor moves, it breaks the bond between the adhesive and the wood or if the tile is weak, breaks the tile or they come loose.

your aim is to get it so it's movement or deflection free, most often mentioned method to test is to put a full glass of water in the middle of the room then walk round it, halfway between it and the wall, if any spills then the floor moved with your weight on and needs stiffening / strengthening before you can tile.


i've done this on mine using noggins approx every foot or so (300mm),
then i've replaced the floorboards with 18mm wbp ply and screwed down every 150 - 300 mm down into joists and noggings so it can't move.

i've got a concrete block work wall on the floorboards in mine as well, not directly over a joist but just off it so probably not as bad as yours!, i cut up to the edge of the wall and then dropped the noggins in underneath tight up to it so atleast some of the weight is down through the nogging and not just the edge of the boards.

depending on where the pipes are, you'd notch the noggin first then fit flush with top edge of the joists,
pipes should cross the joists in notches on the top edge so easy enough to get round, if one falls where you need a noggin,
offset it and double up where you think appropriate.

[haveagohero]

As per warmadmax's post really. Rip up the floor boards, noggins in, 18mm ply (good quality WBP) then i would use 6mm backer boards set into rapidset flexible (cement based) tile adhesive then screwed to the ply through the adhesive, tape the joints then you can either tile onto this (again with cement based rapidset flexible adhesive) or if you want to do a belt and braces job you can use an uncoupling membrane (ditra, dural etc) and tile onto this. For the boards under the blockwork i would cut them back as close as you can but make sure they are well supported by the joists. You need to make sure that the transition between the ply and floorboards is flush on the finished floor otherwise getting your tiles flat will be difficult for an amateur.

For the walls i would make sure that the shower wall is tiled full height to a width that the shower screen is sitting on full height tiles, the joining wall should be tiled to full height by a width of at least 700mm, but you don't need to drop the height of the tiles outside this straight away, they could be stepped down which in general i think looks better. I would tank any areas that will ge getting wet with a paint on tanking kit. I would use a cement based slow setting adhesive and cement based grout in wet areas as water can still pass through grout and adhesive and if you are tiling onto plaster/board the boards will fail, "water resistant" when talking about adhesive and grout only means that the water won't damage them, not that they stop water passing through them.

Hope that helps (and you can understand it)

[Burnz0]

just to confirm - if i do the backerboard as suggested do i put the rapidset adhesive straight onto the flooboards? won't it just fall through the gaps or is it not that liquidy? is 6mm sufficient? if so, it'll be ideal compared to ply as i dont really want to lose any more room height. Will any brand do? is there much price difference? ive only got a 2.5*2 room so it shouldn't be mega expensive either way but every penny counts

[warmadmax]

have you tested your floorboards for movement as above??
backer boards aren't meant to solve the movement issue, just provide a stable base to tile to.