Floating Chipboard Floor over Hetta wet ufh pipes (like polypipe)

[aflemi]

This is about a Victorian conversion property I am buying. I agreed purchase on condition that I fitted out 2 bathrooms.
Builder has constructed the following floor structure:
"The floor make up is as follows.
22mm chipboard glued joints and onto the Ecojoist.

6mm Accusti rubber mat laid over the chipboard c/w foam edging strip

15mm plasterboard plank

25mm polystyrene heat tray

18mm glued joint chipboard."

So apart from the first 22mm chipboard layer glued onto the Ecojoist, nothing is fixed, top layer is interlocking glued chipboard.
UFH manufacturer is Hetta (Swedish) who appear to distribute exclusively through www.ufhtradedirect.co.uk/.
Their brochure isView attachment HETTA UFH BROCHURE.pdf
Ufhtrade direct instruct the following

"Routed floors panel instruction:Simply lay the panels onto your existing screed/floorboards, install the pipe and cover with an interlocking plywood or chipboard floor. Floor covering-Tiles:When tiling, a flexible adhesive must be used to prevent cracking, Tiles should not be laid directly on top of the routed panels."
My builder also advised this:
"Hi Alasdair
The name of the adhesive we have been recommended to use via the manufacturer re the floating floor is Bal single part fast flex. Having used Detra(sic) matting in the past we have found that this does not allow for lateral movement and therefore the tiles crack. This rubberised adhesive should perform far better."
Apart from the comments about builders not knowing their **** from their elbow, I really need some informed advice about how to handle this. I have personally never even tiled directly onto chipboard, never mind over UFH, never mind floating. This is my own property so I cant walk away from it, I really need to have tiled bathroom floors which should be a minimum requirement in my view so I need to solve this.
As an aside, there are 5 other apartments in this development which is covered by the developers equivalent of NHBC, if the builder tiles all other bathrooms in this manner and they fail, he'll have an expensive job to correct.

 

[Diggy]

Well ,

"Having used Detra(sic) matting in the past we have found that this does not allow for lateral movement and therefore the tiles crack."


That is incorrect , both Ditra & F/flex allow for lateral movement ( 4mm is my understanding ) , what they don't allow for is vertical movement.


As for tiling it , personally I woulnd't touch it with a bargepole :smilewinkgrin:

Have you looked at the ecojoists? seems the installation of those is pretty key in relation to any potential deflection.
Just my view though , old school I'm afraid , if it aint screwed then its no way dude.

Diggy :0)

 

[Ajax123]

Why such a complicated floor make up. I agree with Diggy that as it stands I wouldn't touch it with a 50 foot barge pole.

Why not place a screed over the chipboard and tile that instead. provided the joists are able to take the weight you could pin the underfloor heating to the chipboard through a polythene sheet. use anhydrite screed to a depth of 35mm (thereabout) and the tile onto that.

If you want some more detail on how you might do this let me know.

 

[Chalker]

Must be another property below. That's for fire and sound.

 

[aflemi]

Must be another property below. That's for fire and sound.

Yes, its for apartments building regs. In theory I could remove top chipboard layer, replace with 18mm ply marking location of pipes and screwing down to bottom chipboard layer with hundreds of screws. One room is 4x3.3m and plan bath at one end so with weight difference full/empty of +350kg it needs a good base that wont flex every time bath filled/emptied. Have called Mapei and they were sceptical on phone but are reverting by email. Anyone have experience of polypipe install covered with floating layer?

 

[Chalker]

Yes, its for apartments building regs. In theory I could remove top chipboard layer, replace with 18mm ply marking location of pipes and screwing down to bottom chipboard layer with hundreds of screws. One room is 4x3.3m and plan bath at one end so with weight difference full/empty of +350kg it needs a good base that wont flex every time bath filled/emptied. Have called Mapei and they were sceptical on phone but are reverting by email. Anyone have experience of polypipe install covered with floating layer?

yes, but the underfloor panels were covered with fermacell.

 

[aflemi]

Tx Chalker, never used them. Cement boards? So how did that one work then please?

 

[Chalker]

Tx Chalker, never used them. Cement boards? So how did that one work then please?

Best pic I could find.
http://www.jupiterunderfloorheating.com/fermacell.php

 

[aflemi]

Ok can you tell me what the structure was then ?

 

[Chalker]

Ok can you tell me what the structure was then ?

Same as yours. Exept for the plasterboard ( for fire resistance) . Fermacell used instead of 18mm chipboard flooring. You can tile straight onto this.