Best Adhesive for Underfloor Heating?

[epurdy]

HI! am new to the site and a complete tiling novice! Have picked up from previous threads what roughly we need to do but just wanted to check what we're planning to do is right....

we've completely ripped out our kitchen and have so far laid on the concrete floor a layer of kingspan insulation and 22mm chipboard. have brought from U heat 6mm ekoboards insulation to lay where the UFH will go and then everywhere else lay plyboard. these need to be attached to the chipboard using a flexible adhesive of 2mm thickness? Found (and lost!) a thread recommending 2 part and to stay away from single?
once we've laid the U heat UFH we then apply another layer of flexible adhesive before applying ceramic times (30x30). do we need a screed? or can we avoid the extra layer if we're careful when applying the ahdesive.

have seen a lot of recommendations for BAL which seems to be the clear favourite? Only place near us (Guidlford) looks like Topps but any other locations please advise.

sorry lots of questions! :smilewinkgrin:

 

[Gazzer]

So a floating floor then...I am out !

 

[One Day]

Hi, first off; why are you creating a floating floor on top of the existing concrete?
Floating floors and tiling (never mind with ufh) are a job only for a very brave, very experienced pro.
Ekoboards can be bonded using rapidset flexible adhesive. I don't see the need for an S2 adhesive.
Loose cable is relatively easy to fix to ekoboards but matting can be problematic.
Personally, I always screed my cables and mats but ekoboard is so damn soft you may as well not bother, as you'll only crush and deform the screed anyway!
BAL is good (my favourite) but Topps will charge you between 200 & 300% more than the best trade prices. Better using an independant outlet who will be more generous.

Back to my first question though: Is this a floating floor? Does it have to be? If it is, I would really really think long and hard about diying this.
Google "tiling floating floor" and you'll begin to see why.

 

[Daz]

To some degree I've got to agree with Impish.....

I would have bonded insulation boards directly to the concrete screed using a rapid setting single part flexible adhesive. Fix the UFH then apply self levelling compound prior to tiling.

The use of Kingspan and chipboard seem to be adding complication. Can you explain why you have chosen this route please?

Thanks,

Daz

 

[One Day]

Yup, you could have built up height using ecoboard (available >60mm) direct to the concrete subfloor and capped that with proper marmox. Plenty strong enough for domestic use.

 

[epurdy]

Thanks Impish. we've been in the house for a year and found the kitchen extremely cold in winter which is why have opted for extra layer of insulation plus also to ensure the heat of the UFH doesn't disappear down into the concrete.
have been and looked on the forum regarding floating floors and see what you mean - most people have advised against it with the adhesive manufacturers not offering guarantees.
it is definitely a floating floor ( after reading definitions) and think as we've spent so much on the kingspan so far the other half would be reluctant to pull it up (only been down 2 weeks!). the t'other hlaf chose this route but come to lookign at adhesives and it seems to be a lot more complicated than we thought....

 

[epurdy]

The kitchen is old. We've taken up the concrete floor to put insulation down. Underneath the concrete was really old flooring bricks, with no DPM or insulation though at some point in the past the walls have had a chemical DPM in the past. The other half has levelled the old brick floor with mortar, laid a DPM sheet and then put the insulation down. 22mm chipboard went on top of that. The kingspan is specific floor insulation.

Room height is a bit of an issue so we didn't want to put insulation ontop of the original concrete (and the water pipes ran through it so you rarely got hot water in the winter!) - other half did some heat flow calcs and decided that the thinner insulation boards didn't really do much to stop heat loss.

 

[TrumpersUnited]

You need to make the floor deflection free and then use a 2 part like Mapei S2.Otherwise don't bother tiling!

 

[peteablard]

Thanks Impish. we've been in the house for a year and found the kitchen extremely cold in winter which is why have opted for extra layer of insulation plus also to ensure the heat of the UFH doesn't disappear down into the concrete.
have been and looked on the forum regarding floating floors and see what you mean - most people have advised against it with the adhesive manufacturers not offering guarantees.
it is definitely a floating floor ( after reading definitions) and think as we've spent so much on the kingspan so far the other half would be reluctant to pull it up (only been down 2 weeks!). the t'other hlaf chose this route but come to lookign at adhesives and it seems to be a lot more complicated than we thought....

Don't want to sound too harsh but if you tile it and haven't got it right you'll be spending a lot more. Personally I'd go down the same route as Daz

 

[One Day]

Good advice there from Trumpers (!) but it's not just the deflection which is a major concern on floating floors. The potential for excessive lateral movement is there too.

 

[epurdy]

thanks for the advice. decided we've got too much bounce and we're going to pull up the chipboard and the kingspan and lay down a base of joists. don't think we'll be able to attach it the brick/earth floor but hopefully should give us a stable base.
will stick the kingspan in the middle of this and then top with chipboard or plyboard? any advice? preferences on type and thicknesses?? neither will be the surface to take the tile as will add on insulation for the UFH where required and plyboard for under the cabinets.