Bathroom floor tiles, need for plywood under layer?

[lordsainsbury]

Hi

I am remodelling my bathroom and will shortly be laying new ceramic 45x45 cm floor tiles. The existing floor covering is vinyl (which i'll get rid of) and chipboard sheets on to the joists, as opposed to traditional (in my mind anyway) smaller floor boards.

lots of websites recommend putting an exterior grade plywood (9-18mm depending on who you ask) screwed down on top of floor boards then tile onto that.

Is this really necessary? as i imagine the larger chipboard sheets don't move much at all as opposed to skinnier floor boards.

i have two reasons to ask, one i'm hanging the basin tomorrow and need to know what height to work on, and two, i'd rather not have the hassle of putting the ply down and having to plane the door to fit the higher floor.

any advice would be appreciated.

thanks!

 

[Burnerman]

Most people wil know better so wait until they come along, but I was told by a tile supplier that its not a good idea to tile directly to chipboard......so ply it is, ensuring that the floor is dead flat.
John

 

[tictic]

6mm cement based backer boards.

just follow mfr instructions.

but is the vinly stuck down with adhesive??..



meee LORD...

 

[LynR6]

Just a tip which might be useful re tiling upstairs bathrooms where floors aren't solid. I have just viewed a prospective new house and the owner is a professional tiler - amongst other things. His tiling in the kitchen and bathroom was immaculate and I commented on the floor tiles in the bathroom (enquired about the likelihood of tiles cracking due to the flexing of the floor) He advised first using 9mm plywood screwed (countersunk) to the floor plus the use of flexible grout.
Hope this is of help to anyone who hates carpeted bathrooms, as I do!

 

[Richard C]

I have just viewed a prospective new house and the owner is a professional tiler - amongst other things. His tiling in the kitchen and bathroom was immaculate and I commented on the floor tiles in the bathroom (enquired about the likelihood of tiles cracking due to the flexing of the floor) He advised first using 9mm plywood screwed (countersunk) to the floor plus the use of flexible grout.

It's 12mm WBP ply over board or tile backer boards as suggested. The owner of the house your thinking of buying might be telling you he's a pro tiler but he isn't; he's aother chancer using 9mm ply!

 

[jctilingservices]

just read this thread, so this is where the 9mm overboarding came from in a previous thread Rich, i see the point you were making now

If he can overboard in 9mm ( yes i have seen it done before) his floor must have been solid with NO flex in it, even then ,for a pro he is taking a chance. Minimum i would overboard on would be 12 (thats bare minimum) unless i had a height restriction then it would have to be a backerboard

 

[jctilingservices]

meee LORD...

err i do believe thats " me laird" from your neck of the woods davie mate

 

[jctilingservices]

Hi

Is this really necessary? as i imagine the larger chipboard sheets don't move much at all as opposed to skinnier floor boards.


thanks!

yes its neccesary from the point of view that chipboard holds water, can expand and crack you tiles/joints, Do it correctly=do it once

 

[Richard C]

Chip board is not as rigid as you seem to think it is; it’s cheap & nasty crap, even the MR grade. It’s only just suitable as a flooring material let alone being suitable to tile over or for over boarding unless you really want a 30mm+ thick floor. If you want your tile job to last, rip it up & replace it with something decent; 18-25mm WBP ply, depending on joist size/pitch/span.