Flexible adhesive / underfloor heating problem...

[AlexSp]

Hi,

I lay 12sqM of 600x600 porcelain tiles, on electric underfloor heating just before christmas. I used unibond flexible adhesive with the additive to mix... but got stuck when it came to grouting as all the flexible grouts in the local DIY store/builders merchants were every colour but white... so I ended up using regular white grout on the basis, should it not work... breaking it out and re-grouting wouldn't be too much hard work.

Not only has the grouting failed, but the tiles haven't stuck properly either. I used quite alot of adhesive as the heating cable/core is approx 4 to 5mm - so the bed had to be quite thick. The tiles aren't coming up... but do seem to "rock" when you walk over them.

Any ides's on how I could fix this without ripping it all up?

Thanks.

 

[AdrianMealing]

Any ides's on how I could fix this without ripping it all up?

Read more: //www.diynot.com/forums/viewtopic.php?t=277988&highlight=#ixzz1OmLXyg00

Nope you will have to rip it up, was the adhesive cement based? I assume it was, but Unibond is not a make pro tilers would use.

What is the substrate made of, concrete, floorboards, chipboard etc....Suspended floor, floating floor?

I suggest you read the tiling sticky and search the archives for similar posts, this has ben covered many times.

 

[AlexSp]

Hi,

Underneath there is a webbing upon which the heating is attached, and this beneath that is 50mm fibre screed. Not sure if the adhesive was cement based... it was in 20kg bags and had to be mixed up with a milky coloured additive. Ive just tried to find it online and I can't... perhaps this explains something

Will check the links.

Thanks.

 

[mypetearthling]

Did the bag state one-part Flexible or two-part? It is advised by most adhesive manufacturers that you do not add flexible additive to an already flexi adhesive, the result quite often turns to dust under the tiles. Flexi adhesive is already polymer modified and they have a tendancy to react.
Did you put the two together on the advice of someone in the shop you bought it? If so, I'd be tempted to go and have a quiet word so they can sort out their 'training'

If it was two part flexi, it could be that the mix was wrong, or that the heating was turned up too high too soon. Usually this needs to be done gradually.
Use only quality trade products. Avoid anything sold to you by the DIY sheds, and the affectionately known 'Unibomb'.

Read the tiling sticky.

Go through the archived posts in the Tiling forum.

Follow all manufacturers advice.

Avoid white grout on the floor at all costs! It becomes an interesting grey/brown colour pretty quickly. A cement grey is the lightest colour I'd recommend for the floor, but if your heart is set on it, Most of the main manufacturers make a flexi White floor grout.

If there's anything else you're unsure of the Tiling forum is a good place to start.

Good Luck


K

 

[AlexSp]

Did the bag state one-part Flexible or two-part?

I did have great fun with this one... I bought the powder assuming it was "just add water"... got up 6am the following day to crack on with the job. Read the instuctions to find it would only work as a regular adhesive if I added water and I needed the additive for it to be flexible. Went back to the shop and waited for it to open... only to find they didn't stock the additive - so had to driver 30miles to get some.

I was very careful about the mix... I think it was two tubs to one bag, with a few minutes wait before use. I was very careful because the powder and the additive ended up costing a fortune... more than the tiles!!

The underfloor heating wasn't used for a while after completion... as the screed had only been down for about 7days prior to tiling and I was worried about that being affected by the high heat source.

 

[AdrianMealing]

as the screed had only been down for about 7days

Read more: //www.diynot.com/forums/viewtopic.php?t=277988&highlight=#ixzz1On7pzeIP

So was it fully dry when you tiled?

 

[mypetearthling]

Unless you used a rapid set or some sort of decoupling membrane it sounds to me like you tiled onto it too quickly. I think that the standard drying time is something like 1mm per day. Force drying can weaken the screed.


K

 

[AlexSp]

I did give it a while (before the heating was turned on) can't remember how long... but Im pretty sure the problem is adheision between the tiles and the adhesive.

 

[AdrianMealing]

but Im pretty sure the problem is adheision between the tiles and the adhesive.

Read more: //www.diynot.com/forums/viewtopic.php?t=277988&highlight=#ixzz1Oo3bq9Yu

You will know that when you start pulling the tiles up,

I have asked for this to be moved to the tiling forum where i think it is better placed and you are likely to get advice from the Pro's, i am not just a keen DIYER who has learn't the hard way in the past.

 

[mointainwalker]

You should have waited 6-7 weeks for the screed to dry before tiling.