job on caber flooring,with wet system ufh underneath

[deankyall]

hi everyone,
had a call tonight to see if i can posibly find time to do a 50m2 floor before end of next week,had a look,its all caber flooring screwed to i assume joists,its ground floor ,new extension,underneath is wet floor ufh ststem,they had marmox thermal boards there,which i said were wrong as the heating is underneath the caber flooring,i suggested ditra,so firstly would you use vs90 or singlepart flex or 2 part flex? to stick ditra down? secondly would the mapei fleece be sufficiant instead,any suggestions would be great as they want it started monday,cheers..
sorry forgot,just porcelain going down

[Bubblecraft]

Personally, I'd use 2 part flexi mate


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[nybor62]

you cant tile onto caber boards , over lay with ply min 15mm wpb or cement boards 10mm

[deankyall]

thats what im saying can the dietra be put on top and if so what would you stick with,ie 2 part spf

you cant tile onto caber boards , over lay with ply min 15mm wpb or cement boards 10mm

[deankyall]

or do you mean overboard with hardie backers first then dietra ,the ufh is underneath the caber flooring so i assume there will be a lot of movement.

[Bubblecraft]

You CAN tile straight onto Caberfloor whether it's P4 or P5, 18mm or 22mm if you have a height restriction. I'd always sheet where possible but you can if need be with a 2 part flexi & is also suitable for UFH & steel surfaces. As the UFH is under the Caberfloor, you will loose alot of heat putting down Hardibacker or WBP.


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[Dave]

Caber floor/chip board is not a suitable product to tile directly to, yes adhesives will stick to it but it is not structurally stable enough to hold tiles in place.

Hardi backer boards will not effect the U-value but marmox types boards can... over lay with hardi backer 250(6mmm) and screw down with screws and use ones that will not be longer than the hardi and caber depth... Use alkaline resistant joint tape on the boards joints and tile with a single part S1 adhesive...

[deankyall]

You CAN tile straight onto Caberfloor whether it's P4 or P5, 18mm or 22mm if you have a height restriction. I'd always sheet where possible but you can if need be with a 2 part flexi & is also suitable for UFH & steel surfaces. As the UFH is under the Caberfloor, you will loose alot of heat putting down Hardibacker or WBP.


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thanks dave, this is the route i am suggesting to this customeralso would you deitra this too as its ufh under the caber?,as i said they had thermal boards delivered when i went to price it,so told them it was wrong,trouble is ,after an £80,000 extension they dont have much money( how come its always like that when it comes to finish?) and a novice builder who knows nothing about tiling,so i will tell them and leave it at that,have not got the time to do all this anyway 50m2 with all the board ,mat etc in 2.5 days impossible.
i think ill call nick walker at mepei tomorrow and see what they will spec.

[Dave]

If it was stone tile installation then i would incorporate the likes of Ditra, but with porcelain then if no deflection then Hardi alone will suffice... use adhesive under the boards to take up any undulations in the substrate and then the S1 to adhere the tiles.

[deankyall]

If it was stone tile installation then i would incorporate the likes of Ditra, but with porcelain then if no deflection then Hardi alone will suffice... use adhesive under the boards to take up any undulations in the substrate and then the S1 to adhere the tiles.

what would you use under the hardi dave 2 part? its pretty flat.

[Dave]

No just single part, the adhesive is basicly to take up any voids created when screwing down etc...or within the substrate..

[merit]

had this issue a week ago , a floor that had been put down a year ago by a nother tiler had popped,its in a wet room
with restrictions on height to the mosaics in the shower former,porcelain tiles up to it need to come up and be relayed but i
dont know whats under there, i suspected they had been blobbed , i now know they were installed on caber, phoned bal tech and they said go ahead with bal fast flex, in normal circumstances i would hardi but trying to match existing, whats the solution ?

[Bubblecraft]

I don't disagree about the fact of re-sheeting. As I said, I always re-sheet where possible but if there is a height restriction, 22mm P5 with 400 centres is sufficient enough to be load baring for any tile & is suitable for UFH. I agree, it's not ideal & I avoid where possible, more so in a wet room where I would only re-sheet & tank. My debate was more the fact people saying you cannot tile on Caberfloor when you can, excluding surrounding circumstances of course


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[nybor62]

imo you should not tile directly on to caber boards it clearly states in bs 5385 part 3 that they should be over laid as to give the rigidity for a tiled surface.
i am also of the understanding that the resins in theses boards dont allow the addy to bond . causing tiles to debond eventually