Travertine crack accross 4 tiles

[Rich]

So if using this method would the heat still transfer through 22mm chipboard+15mm ply and then through a cement board ?

Sorry, have just read my own post, Im a doughnut.

 

[DHTiling]

Sorry, have just read my own post, Im a doughnut.

....................

 

[DavieA]

Yeah seems very thick.

the wet ufh currently is being installed then new 22mm chipboard being layed. Spoke to joiner who is very good and work with alot about replacing chipboard with equivelant ply and he wasnt keen said chipboard gives more strength and is t&g. however would it be best for me to say if once hes fitted and fixed chipboard is happy floor is movement/deflection free just to over board with cement board glued (with?) and screwed at 150mm?

Never used cement board so excuse the 20 questions Rich:yikes:

Cheers

By the way GREAT post...

 

[Rich]

To be honest I would rather have a 22mm ply floor than a 22mm chipboard floor. You have to remember that this guy is a joiner and as good as he may be he is not a tiler. Once this floor is tiled, it will have your name on it. You have to get the prep right now in order to insure a good finish. I would say that you want ply put down instead, that is unless anybody would disagree?

When he lays the ply, get him to seal the under side and edges of the boards, leave an expansion joint of 2-3mm between each board and screw it to death. Once this is down, lay the cement boards and tile in confidence.



Here is another link, biot of info on Hardiebacker. Hope it is of some help.

[h=3]HardieBacker...[/h]

 

[DavieA]

Yip fair point. Ive nothing like the experience of you tilers on this fourm so if thats a recomendation im on board.

So if using wbp ply straight onto joists it must be 22mm minimum? and its not in wet area its hallway,kitchen and dining room would it still require to be sealed underside and edges and is it with the likes of mapei primer b?

 

[doug boardley]

it sounds to me like the ply has heaved with expansion, due to the sheets being butted tight.

 

[DavieA]

Everyone talks about deflection and no more than 3mm per 400mm but how do you accuratly measure it?

 

[Rich]

No British standard is min of 15mm BWP marine grade ply fixed down at a min of 300mm but 15mm is not so easily available so most use 18mm ply if height is a problem but I like to go as thick as I can. It is still a good idea to seal the underside and edges of the boards, this gives a bit of protection from moisture from underneath. Was that meant to say primer G? That will be fine. When it comes to deflection I have one simple rule "if there is any deflection then you can expect your floor to fail". You are lucky enough to have a say in this before the ply goes down, if the floor needs it, then get the joiner to add some noggins and like I said screw it to death. You want that floor as rock solid as you can get it.

 

[DavieA]

Yeah Primer G, think im loosing the plot!

Ok before i get more info and speak to joiner tomorrow could you help me out?

If floor is deflection free will it make a difference wheither 22mm ply is layed with 2-3mm expansion gap and screw to death up joists or 22mm chipboard layed and screwd to death up the joists?

Are both Ply and Chipboard suitable to have backerboard fixed to using flexible tile adhesive and screw fixing method as per your post?

form experience whats options if deflection exists bering in ming UFH heat transfer?

Thanks again everyone

 

[doug boardley]

chipboard has a tendency to curl up at the joints when only slightly moistened, ply and backer boards all the way for me.