Limestone on a chipboard floor, with UFH!

[DJS]

Been asked to tile an en-suite bathroom floor with the possibility of underfloor heating. As I am still wet behind the ears in this game, I want to check I got it right before I go back to the customer.

Customer is insisting on a natural limestone floor, probably something like beige 450mm tile. Room size is 2.2m x 2.0m and the floor is chipboard, with no wax coating.

Q #1 Would you recommend white flexible adhesive with latex additive? I'm thinking yes!

Q #2 Would you insulate before fixing the UFH wires and what is best material? Eg Marmox? I'm not sure on that, don't think so!

Q #3 Would you feel a de-coupling membrane would still be required, if using that level of flexible adhesive? The wooden floor is solid, but I am concerned about expansion and contraction from the UFH on the natural stone. I'm thinking yes!

The customer has said, he plans to sell the apartment in 5yrs time and wants it to look the same as the day it was installed (by me hopefully!!).

Thanks in advance for any advice given.

 

[nybor62]

yes i would insulate first fit ufh then self level over. how well is the chip board floor down , is there much deflection

 

[grumpygrouter]

Decoupling is essential with limestone and UFH in my opinion. The floor isn't big so should be pretty rigid but it still needs confirming so. Speak to U-heat for insulating boards.

 

[DJS]

Cheers guys, and who or what is U-heat?

I just been reading the manual for warmup UFH, and they recommend the use of the insulation board with their UHF systems (no surprise there '£££).

It seems the main benefits are :- It will half the time it takes to warm up from 45 to approx 20 mins, and reduce running costs. I can't seem to find any other reasons other than that for using it. Ie. It will not add to the strength of the floor.

The joists are solid and the chipboard is reasonably new and looks in good condition. It is small (2mx2.2m) and very little or no deflection.

About half of the chipboard may have to come up anyway to re-route waste pipe's for swapping the location of the toilet and sink. So even if I replace the chipboard with WBP ply, it may reduce the need for a decoupling membrane, but then there would still be a case for stress crack isolation membrane possibly.....now my head is really pickled!!

Maybe the right way to go would be install a DC membrane if he goes for UFH. And a SCI Membrane, if he doesn't want the UHF. Eitherway, the chipboard can stay.

 

[diamondtiling]

Underfloor Heating | Electric | Floor Insulation | Uheat

Chipboard is not a stable tiling substrate

 

[Yorkshire Tiling Services]

Been asked to tile an en-suite bathroom floor with the possibility of underfloor heating. As I am still wet behind the ears in this game, I want to check I got it right before I go back to the customer.

Customer is insisting on a natural limestone floor, probably something like beige 450mm tile. Room size is 2.2m x 2.0m and the floor is chipboard, with no wax coating.

Q #1 Would you recommend white flexible adhesive with latex additive? I'm thinking yes!

Q #2 Would you insulate before fixing the UFH wires and what is best material? Eg Marmox? I'm not sure on that, don't think so!

Q #3 Would you feel a de-coupling membrane would still be required, if using that level of flexible adhesive? The wooden floor is solid, but I am concerned about expansion and contraction from the UFH on the natural stone. I'm thinking yes!

The customer has said, he plans to sell the apartment in 5yrs time and wants it to look the same as the day it was installed (by me hopefully!!).

Thanks in advance for any advice given.

Make sure no deflection on floor
Alos,because it is such a small area,then hardly see the need for de-coupling, unlikely that there will be any lateral movement on floor if properly prepared.
Would use insulation boards cemented down with Bal Fastflex. Self level over cable prior to tiling,then use flexi adhesive to fix.

 

[diamondtiling]

Go to your nearest Tilegiant and use mapei.

 

[Yorkshire Tiling Services]

Go to your nearest Tilegiant and use mapei.

Can buy Bal at CTD just about as cheap as Mapei at my local Tile Giant.
Do not understand why such a downer on Bal as a whole,they make some great products.
Again, do not want to get into a brand slanging match here,although some may be trying to direct it that way.

 

[nybor62]

bal mapei both as good as each other, webber, norcross ,great addys we could go on for ever

 

[Time's Ran Out]

Can buy Bal at CTD just about as cheap as Mapei at my local Tile Giant.
Do not understand why such a downer on Bal as a whole,they make some great products.
Again, do not want to get into a brand slanging match here,although some may be trying to direct it that way.

I would have thought that advice about another brand of adhesive was essential for a disscussion forum without it being 'again' labelled a slanging match!
IMO it would only seem appropriate that MAPEI who are a valued sponsor of the Tilers Forum, have the support of members who prefer their products.

DJS - for my input on your thread - I'd use a decoupling on all stone where ufh/wood is involved!

 

[DJS]

My plan was to ring and check with someone tomorrow, but as it's the weekend I wanted to find out asap so I can finish my quote. I've got another to do tomorrow, but I'm ok with that one.

My local independent shop sells a couple of good adhesive brands including Mapei. Not saying I prefer them, but at least the shop sells stuff that can be trusted and my prices off them are ok.

My gut feeling is with Timeless John & Grumpy Grouter - even though the floors not that big, my concerns are- Natural Stone (and limestone too), UFH & Wooden sub-floor, a young couple in their 20's for the customer with a 1200x900 double shower tray....plenty of scope for movement if you ask me :smilewinkgrin: I'll still ring a couple of people for their opinions tomorrow, but I feel the installation would benefit from one in terms of longevity.

So the plan for correct floor prep would be something like, replace 22mm chipboard with 18mm WBP ply, primed (check adhesive instructions), flexible adhesive suitable for use with 6mm insulation boards, UFH, flexible self-level, flexible thinset with DC membrane, then tile over the top with white latex 2pt flexible.

And just to throw another question into the debate - the walls are skimmed & painted 9.5mm plasterboard. So I'm also right in thinking thats all got to be replaced with 10mm or 12mm bakkaboards, due to the weight of the stone. Again, I will check 2morrow, but value your opinions too, especially if it helps me get the job done quicker.

 

[DHTiling]

DJS.. any timber floor will expand and contract.. when you use a softer material like limestone/Travertine etc then there is the risk of cracking at joins in the timber substrate, so these membranes are there for a reason..stone isn't cheap so why risk a failure.

You can only advise to a customer a fail safe method and it is up to the customer to decide to go for it or not.

The phrase "i have always done it and never had a problem" is Neanderthal in the tiling world, a fixer should always strive to give a long lasting installation.

 

[DJS]

You can only advise to a customer a fail safe method and it is up to the customer to decide to go for it or not.

The phrase "i have always done it and never had a problem" is Neanderthal in the tiling world, a fixer should always strive to give a long lasting installation.

Dave, you have put my mind at ease with that. I can only advise them on what is best. What they are willing to pay for, is what I will do.

Now I feel the need to go back to this couple and go through exactly whats what. I think they will reject the UFH anyway, but I will strive to convince them a DC membrane and 22mm WBP would still be a good investment.

I though it would be a cheap job as it's in the middle of studentsville, manchester. How wrong can I be!!

Thanks to all for your advice.

 

[The Legend; Phil Hobson RIP]

DJS.. any timber floor will expand and contract.. when you use a softer material like limestone/Travertine etc then there is the risk of cracking at joins in the timber substrate, so these membranes are there for a reason..stone isn't cheap so why risk a failure.

You can only advise to a customer a fail safe method and it is up to the customer to decide to go for it or not.

The phrase "i have always done it and never had a problem" is Neanderthal in the tiling world, a fixer should always strive to give a long lasting installation.

Well said Dave

 

[Yorkshire Tiling Services]

My intention was to initiate,profession adult debate in response to comments. As said,I use a multitude of products.
For someone to say "Mapei is better than Bal",this requires clarification & evidence.
An un clarifed statement carries no weight.
Anyone rubbishing an entire brand,must have reason to do so.
Perhaps the brand rubbishers would like to share their experiences with any products that they have used within the range & explain & compare to other like products from other brands !
Pot life, workability,ease of use,cost,faliures after using.
If we are going to have public debate for the benefit of users,then let's try keep this relevant,professional & informative.
I know cost is a big issue with Bal,some of their products are considerably dearer than others. This does not make them inferior.