Help!: Bathroom backer boards

[MickFussey3]

Hi I am about to under go the job of tiling my bathroom floor and walls .I only have a maximum thickness after I have removed the floorboards of 22MM. Can I lay Hardie or any other 12mm tile backer directly to the joists which are 24mm apart without ply as the tile I want to use is 10mm.
If i can this would be the perfet measurement
Mick

[Martyn Leeds]

It would probably be a perfect measurement, but its more likely to be a perfect fail also.

When tiling floors there's almost always going to be a slight step. What is restricting the height?

[MickFussey3]

I have 22mm from the top of the joists to the hallway threshold

[Rich]

No I wouldn't use the backer boards straight onto the joists, why dont you see if you can get your hands on some 15mm boil and water proof ply and then over board with 6mm backer?

[MickFussey3]

I was thinking along those lines, so the following
tile is 10mm
the ply is 15mm
backer is 6mm = 30mm looks like I am going to have a step almost .
Thanks for your help
Mick

[Brian the Tile]

ive just got to say i dont get all this about taking floorboards up then laying down ply and then bacerboard ,or am i missing something here prey tell me why not onto the ply itself if is the right thickness and srewed not nailed correctly

[Rich]

Ply is not a good surface to tile onto, have a read throught the link below on plywood floors.


Plywood floors...

[Brian the Tile]

hi Rich,so does this mean to say that for the last god no how many years i have not been dooing the job right theese backer boards do you know how long they have been around? just finished a job today where it states on the tile boxes to use ply on wooden floors and also use pva to seal it with {whitch i dont use by the way}, been tiling a long time now but im always willing to listen

[Rich]

Did you read all the replies to that thread? Had some brilliant responses from guys that know a lot more than me. The problem is really the poor quality of the ply on the market now a days. I do not tile straight onto ply anymore as I have seen so many failures (thankfully not with my own work) when tiles have been laid onto ply. The backer boards give a fantastic surface to tile onto and for the price I think they are well worth using. A very large percentage of my work is correcting failed installations and 9 times out of 10 tiles have lost their bond to a ply back round.

This isnt to say that every floor tiled straight onto ply is doomed, but if using backer boards reduces the risk of failures then I think its worth it.

[Rich]

Might be worth doing a search on here if you want some more info on backer vs ply, or put up a new thread asking what people think, should give you a pretty good cross section of opinions on them

[Brian the Tile]

think i will stick to what i know works best,old school hard to change Rich all this newish stuff who knows,why fix it if its not broken

[MickFussey3]

I am taking up the floor boards because if I put the backing board or the ply on top of the existing floorboards then the tiles I would have at least a 16mm if not more of a trip hazard into my bathroom.
As I explain in the previous email there is only 22mm to play with to the height of hallway threshold, I want as little trip as poss , so I have decided with the help of all to take up the floorboards put noggin's in frequently, lay 12mm ply screwed to the joists & noggin's, then water proof membrane stuck to the ply, 6mm backing boards stuck and screwed to the ply and not the joists then 10mm tiles giving me 6mm threshold. When I lay my new carpet I will put a chamfered gradual wedge under the carpet to lose the trip.What do you think ? is that solid enough or will it crack???

[chille]

think i will stick to what i know works best,old school hard to change Rich all this newish stuff who knows,why fix it if its not broken

I can see where your coming from, but if we all believed/carried on with the things we did 5 years ago there would be no improvements. It wasn't that long ago that asbestos was the best thing to use for a whole load of things, now we know different and try to improve on things.

[chille]

I am taking up the floor boards because if I put the backing board or the ply on top of the existing floorboards then the tiles I would have at least a 16mm if not more of a trip hazard into my bathroom.
As I explain in the previous email there is only 22mm to play with to the height of hallway threshold, I want as little trip as poss , so I have decided with the help of all to take up the floorboards put noggin's in frequently, lay 12mm ply screwed to the joists & noggin's, then water proof membrane stuck to the ply, 6mm backing boards stuck and screwed to the ply and not the joists then 10mm tiles giving me 6mm threshold. When I lay my new carpet I will put a chamfered gradual wedge under the carpet to lose the trip.What do you think ? is that solid enough or will it crack???

I really hope it works ok for you, but if it was my house 12mm ply on top of joists wouldn't even be considered. If you want to avoid a 16mm step up then use Karndean or something similar

[Mike]

I am taking up the floor boards because if I put the backing board or the ply on top of the existing floorboards then the tiles I would have at least a 16mm if not more of a trip hazard into my bathroom.
As I explain in the previous email there is only 22mm to play with to the height of hallway threshold, I want as little trip as poss , so I have decided with the help of all to take up the floorboards put noggin's in frequently, lay 12mm ply screwed to the joists & noggin's, then water proof membrane stuck to the ply, 6mm backing boards stuck and screwed to the ply and not the joists then 10mm tiles giving me 6mm threshold. When I lay my new carpet I will put a chamfered gradual wedge under the carpet to lose the trip.What do you think ? is that solid enough or will it crack???

12mm ply is not thick enough to prevent deflection, you need at least 15mm (bs standards)

[MickFussey3]

Thanks I will go for 15mm sound better Mick