the correct adhesive method over under-floor-heating

[Unregistered]

Hi all, i am just about to spend a lot of my hard earned on having underfloor heating and tiled floor in my kitchen-diner. I always leave these jobs to the professionals but like to educate myself a little to avoid being taken for a mug. Once the underfloor heating is laid in a self leveling latex type stuff what method would you use with the tile adhesive? should i expect complete coverage under the tile or can you use a lump in each corner and one in the middle? sorry for the layman description but all help would be most welcome. Many Thanks, Steve.

 

[grumpygrouter]

Re: the correct adhesive method over underflorr heating

Hi Steve, if you registered with the forums, we would be better able to keep track of your query regarding further questions and answers.

I assume you are talking electric UFH here? It is normal to lay the heating mats on insulating backerboards first of all. Then, I always lay self smoothing compound on the top to protect the cables and give a better surface for tiling on to. Adhesive should be laid to provide a solid bed underneath the tiles. Dabs in the corners and centre of the tiles ARE NOT acceptable!

Grumpy

 

[Unregistered]

Re: the correct adhesive method over underflorr heating

Cheers Grumpy. is it acceptable to have any voids under the tiles? the truth is they started laying the floor the other day and my wife said she saw him laying with a dot and dab method. the floor is nearly finished, so am i to assume that the electric underfloor heating wont penetrate the tiles because of this? i dont think i'm going to like your reply......gutted.

 

[steve3]

Re: the correct adhesive method over underflorr heating

Cheers Grumpy, just registered. To be honest they started tiling last week and my wife said she saw them using the dot and dab method. Can i assume that if there are voids under the tiles that the electric underfloor heating wont work properly? cheers.

 

[Gazzer]

Re: the correct adhesive method over underflorr heating

Dont use dot and dab. If you do the tiles will sound hollow, they will be prone to breakages and infestation of insects etc.
Lay the UFH and either as Grumpy states SLC over the top and tile at a later stage. Or you could tile straight over the UFH but this can be tricky as you may damage the UFH elements. Using a plastic notched trowel will help if you choose the later method.
I would go with Grumpy and Lay UFH and then SLC. Better job in my opinion. You only need to cover the UFH with SLC as the more SLC the harder teh UFH has to work to get heat up to the tiles.
When laying i would spread the floor with a notched trowel and depending on the tile chosen you may find buttering the back of the tile will be needed too.

 

[grumpygrouter]

Re: the correct adhesive method over underflorr heating

Cheers Grumpy, just registered. To be honest they started tiling last week and my wife said she saw them using the dot and dab method. Can i assume that if there are voids under the tiles that the electric underfloor heating wont work properly? cheers.

You quite catagorically DO NOT want voids under the tiles. Not only does this reduce the efficiency of the UFH but the tiles will be much more prone to breakages - stiletto heels will penetrate them - Also I do believe that is contravenes British Standards but don't quote me on that one.

If they have Dot n Dabbed then I would be inclined to ask them to start again!

Grumpy.

 

[Gazzer]

Re: the correct adhesive method over underflorr heating

You should be able to tell if they have " dot and dabbed" by gently tapping the tiles with something like the end of a broom. If they have dabbed then you will get different sounds from the tile. A coin etc can be used too just be gentle, you dont have to tap too hard.

 

[enduro]

Re: the correct adhesive method over underflorr heating

I bet you wish you hadnt asked now Steve...:furious3:

 

[steve3]

Re: the correct adhesive method over underflorr heating

I bet you wish you hadnt asked now Steve...:furious3:

well i would rather know and i thank you all for the advice. The only saving grace is that i havent paid yet (apart from the tiles which i sourced, which are 600x600 porcelain) and i wont hand over any money until i have fully tested the underfloor heating, which by all accounts takes a while as you have to up the temp over many days by 1 degree a day? and if i'm not completely satisfied by then i dont know where i stand in making them do it all over again.....i dont think i could take all the upheaval.

 

[ladytiler]

Re: the correct adhesive method over underflorr heating

we had some under foor heating installed and the guys tiled straight over the matting, no self level compound at all.

i watched them because i was worried about the cables being cut but, they spread the adhesive flat with the flat side of their trowels so the adhesive covered the wires and then they used the serated adge to plough their lines. is this correct or wrong, id like know for future ref

thanx

 

[Gazzer]

Re: the correct adhesive method over underflorr heating

There is nothing wrong there Lady tiler. Its just that some prefer to use SLC before and tile at a later stage.

 

[Holohana]

Re: the correct adhesive method over underflorr heating

hi Steve3. If you do ask them to rip up and start again because they have dot & dabbed then this will almost definately damage you ufh cable unless they are very carefull.

 

[davy_G]

Re: the correct adhesive method over underflorr heating

Id use SLC for a couple of reasons.
One, it protects the mat form my big feet and tools while tiling.
Two, it leaves a good surface to tile off.
Three, Any air voids around the mat, below the tiles will act as an insulator and reduse the thermal transfer of heat to the tile. In the worst case of the cheeper wires they can burn out as they heat up too much with just air around them.

Agreed with Grumpy, always try and install 10mm dense insulation boards, can be up to £20 a m2 but the tiles will be warm after 20 min as opposed to 3 hrs. Long term savings.

No tiler worth their salt should be using dot and dab, very poor show indeed.

I would ask them to explain their tile fixing methods and any concerns you have about them as early as possible. As they are finished, or nearly finished I would let it go and see how the job turns out, ie boast tiles, efficiency of the heating. They should have liability insurance that should cover UFH and that might be the way to go if things are not to your satisfaction.

 

[Daz]

I'd say you're damned if you do and you're damned if you don't!
I'd make them take it all up, but make sure you do a tap test first! Proves your point.

If the underfloor heating is damaged, then that is their responsibility - tough!!
SLC is not compulsory as long as tiler is half decent.

You expect to pay for a pro job, so make sure you get one!!

Good luck - If you're near me (Cambs) I'll give a pro assesment.

 

[sean384]

What I always do is get a sparky on board, so once i've layed the UFH system he will come out and test the system before I lay the SLC, he will also test it again once tiled. I do this in front of the customer both times so they can see it works.

 

[steve3]

thank you all for your welcome advice. the job is finished now and does look good but we have decided to wait untill the ufh is wired in and tested properly before we hand any money over. i have tested the tiles with a coin and can only just pick out a couple of places where there is a different sound and even then its not horribly hollow sounding. before they tiled they laid a slc over the mat and let it dry before they started tiling. i realy hope that it all works. i will let u all know when i have tested it fully. thanks again everyone. steve.

 

[DHTiling]

don't forget steve..there will probably be a commision time before you can turn the UFH on. This is usually 8 days or more...check with the mat suppliers.......

 

[me_a_guest]

Hi, sorry for starting this thread up again but I googled the very question and came here, my questions isn't quite answered so thought save wasting time on a new thread I'd just bung it on.

I've just had UFH installed, it's the wet type, pipes and manifolds and all not electric.

I'm about to start tiling the bathroom but was wondering what's the best type of adesive and grout to use?

Do I want a cementious chemical reaction type drier (like cement for those reading who've not heard of the term before) or do I want a dehydrating type (like pva glue, the water gose and the adhesive goes hard).

THANKS!

 

[robbieraven]

Dot and Dab, never let those two words be used in the forum again Evil!

 

[Bubblecraft]

4 year old thread? Really?