Tiling onto aluminium Wundafloor heating

[robwatsontiling]

Hi,
I'm due to start a job tomorrow installing beautiful 600x600 black basalt tiles onto a wet ufh system from wundafloor. However I'm really concerned about the advice I've received from wundafloor. On speaking with them they say that tiling directly onto the system with any s2 adhesive is fine with no primer or self levelling required. I was going to use bal single part fast flex s2 but think maybe I should use mapei just incase there are future issues with liability.

Substrate is concrete base, 100mm insulation, then the wundafloor system with aluminium spreader sheets.

Wundafloors own installation guide states that mapei primer must be used prior to 5mm mapei slc then tile using mapei s2 which even contradicts there own sales staffs advice to me.

Has anyone tiled onto this system? All advice welcomed.

Link to wundafloor installation guide...
http://www.wundafloorheating.co.uk/download/F01%20Overfloor%20panel%20fact%20sheet.pdf

Still seems a bit foreign to me to tile onto aluminium/insulation directly.

Help!!

Cheers.

 

[trevortine]

Never done this but Mapei s2 ultraflex is on special at CTD just now! Fraction of the bal price.

 

[Ajax123]

When you add water to cemet you produce hydroxyl ions. These react with un oxidised aluminium to evolve hydrogen gas which will cause a honey combing effect in your adhesive thus weakening it considerably. The aluminium shoul be primed in my opinion to prevent this reaction. However that would weaken the interface bond as yu would be sticking to primer and not aluminium. If the primer is not firmly adhered to the aluminium the tiles will delaminate.

sounds dodgy as heck to me...

 

[Time's Ran Out]

Bit late to offer advice if your starting tomorrow! Still I'd get it in writing from wundafloor and also from Mapei before I committed to the job. Not done it myself so interested in other replies.



Ajax to the rescue - knew it was iffy.

 

[Del W]

If the installation guide says use mapei why would you use bal ?

 

[robwatsontiling]

I prefer using bal to mapei. Personal choice I guess. But my first advice from wonder floor was that although mapei had tested it, any S2 adhesive would be ok.

 

[robwatsontiling]

Yea it's a short notice job. The closer I get to starting it, the more nervous I get about it.

 

[Rookery]

I can understand your nervousness. Expensive if it fails and you can bet your bottom dollar that you'd get the blame from your customer if it did. I've not tiled over this myself but personally and especially in view of Ajax's comments re the chemistry, I absolutely would not proceed without first getting Wunderfloor to agree in writing the exact spec and with you following it to the letter. Along the way I'd back myself up by keeping a written and photographic record of the proceedings.