Travertine crack accross 4 tiles

[DavieA]

Hoping for a bit of advice.

Called back to a tavertine job i did about a year ago for a mate. Found 2 seperate cracks that stretch in a straight line accross width of the floor and beleive there where the 15mm ply sheets butted together, therfore think there must be movement in floor?

Ply was screwed in to floorboards to ensure no bounce and obviously floorboards arnt suitable to tile on and used flex addy and grout along with thick bed fixing method.

Told my mate to add dwangs inbetween joists from basement to stenghten bathroom floor is this a good more to solve this problem or whats the best remody?

Thanks guys

 

[jay]

what thickness ply and name of adh would help

thanks

 

[DavieA]

It was 15mm and keraflex maxi Jay.

Cheers

 

[Rich]

Were the boards butted up together or was a gap left? There should be a small gap for expansion. Ply will expand and contract with moisture/humidity, if the boards are butted up together then they will "tent". This often causes tiles to crack along this line.
The tiles will need taking up whatever the cause, take them up and if there is no expansion joint, add one. It only needs to be 2-3mm.

Or it could be that the end of these boards are not sitting on the joists so that, as you say, there is a bit of movement causing the tiles to crack. This will need to be supported before re-tiling.

 

[DavieA]

I think they were butted together my mate did the plying. Think I will try strengthening floor and if problem persist put in 2mm gap in boards.:mad2:

Was ment to have a 45m2 travertine floor job but this has dented my confidence a tad and am unsure wheither to take job on.
Job comming up is over wet ufh aswell, intention was to overboard the chipboard floor with 15mm ply to ensure strength then lay dural ci+ and lay tile using keraflex on a soild thick bed.

What do you guys who have tons more experience than me think? Id be gutted if anything happened to a customers job.

 

[Rich]

I think you should just take this as a lesson. You have to know that the floor your about to tile onto is fitted correctly. I dont think you should go turning work down over this. Take the work but just swat up on here before each and every stage of the project. If this has knocked your confidence, just think how much it will improve your confidence when you complete 45m of trav knowing that it is done properly.

 

[DavieA]

Good advice, Thanks.

Would the steps listed be suitable or is cement boards recommended instead of ply? Mapei tech say ply is superb or ixing using there addy and i know 15mm would add strength.Ive been toying over this because i want a strong floor or tiling but heat to be passed through no prob and amnt 100% on 22mm chipboard+15mm ply then decoupler and addy.

 

[White Room]

Did you use a decoupler with the trav

 

[DavieA]

No not this time as no ufh and room was about 5m2 but do if ufh is involved and tiles are porcelain,travertine or another natural stone.

 

[White Room]

I find trav is soft so tend to use a decoupler on timber/ply floors..

 

[DavieA]

So your quite happy to use ply as a sub, take it 15mm minimum and always use a decoupler with travertine wheither ufh is involver or not?

 

[DavieA]

2 things just popped into head,

Type of decoupler you use and is it recommended?
and do you only use WBP ply thats treated or standard ply do?

just help me with thought process.
Thanks

 

[White Room]

I like 6mm hardie backer boards but have turned up on jobs that have had a ply overlay by a plumber that I get work from..he started to listen now but it's taken a while..

I have only used ditra and not had any problems with it..

 

[Rich]

Ideally I like to have a good thick ply floor (fixed down 150mm - 200mm) then over board this with a 6mm cement board. I think this gives about as good a substrate to tile onto as you can get with a wooden floor.

 

[DavieA]

Cheers Rich do you never tile directly onto ply and what thickness would you use if you had choice?

 

[The Legend; Phil Hobson RIP]

Same as Rich for me,

 

[DavieA]

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

 

[Rich]

As thick as you can get away with.




[h=3]Plywood floors...[/h]Here is a post I put up a little while ago about wooden floors.

I dont like tiling straight onto ply because I have put right countless installations that have failed over the years and I think tiling onto ply is problematic. If I dont have a choice, I like to use a 2 part adhesive. Have a read through the link above, it gives my view on tiling onto ply but also some brilliant responses from tilers that really know their stuff.

 

[Stewart]

Tip top advice above from Rich....

 

[Rich]

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

I doubt it to be honest, if it does then I think that it would take a long time to warm up. What kind of condition is the chipboard in and how thick is it? If it is ok and you can fix it down so there is no movement in it, you could over board with cement boards and forget the ply. If the chipboard is not in very good nick, is it possible to remove it and replace with ply?

 

[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.

 

[Rich]

As above. If there is bounce in the floor, chipboard or ply, you need more screws and more noggins.