underfloor heating installation

[tim000]

Hi, i'm Tim and I am new to the forum. So a quick intro from me, im an electrician but a quite keen diyer and have done quite a bit of tiling over the last few years. I have read this forum for info and advice regularly and so far none of my projects have gone badly!.

Now the intro is out the way, I have a few questions I would just like to clarify before I install ufh for the first time. I am installing in to a up stairs bathroom on floor boards. I have purchased 6mm NMP and will glue and screw this down first. I will lay my heat mat on to this. I , at first, was going to install the tiles directly on to the heat matt in the adhesive but after reading the forum found people recommend using a SLC first. This to me seems a much better as it takes out the risk of damaging the mat with the trowel. What do I need to look for in the SLC and adhesive to be suitable for my installation and any recommendations? The tiles I am using are ceramic and a sandy colour so a light coloured adhesive would be preferable. Thanks for any advise!

 

[White Room]

Personally I would have fixed thermal boards on the floor to get the maximum heat reflection.

I tend to use Ultra 2 part slc (others will have there own favorites) and would go for white adhesive with the light colour grout.

 

[Sean Kelly]

I would have used thermal boards too, or 6mm Hardibacker. A two part self levelling compound should be used. First part being the powder and the second part is the latex. You can buy the 'Ultra' 2 part system in Topps tiles. I personally use Mapei 2 part slc from CTD. The adhesive should be a white single part flex. i.e. a powder that you mix with water. Read the label and it should tell you that it is suitable for UFH. Remember not to put the heating mat under the toilet or vanity unit etc.
Good luck and welcome to the forum.

 

[trustiling]

Draw on your floor where any sanitary ware should be.

Measure in 0.5m widths ,from where your supply will be, linearly, until floor space used up then divide this figure by two to get the exact size of mat you need so you don't need to 'lose' any.
Never cross the wire, make sure the joint from power source to heated cable is under tiles area and thermostat is in between the ring of two elements and housed in the conduit in case of future failure for removal. It helps if you use a thicker insulating board then you can recess the conduit a little more in the floor.
Don't staple the wire but staple the mesh down as much as possible as it will dog ear/curl when you screed it if don't leaving an uneven solid surface to tile.

You can also use Weber fibre flex single part with water.

Don't turn it on for a couple of weeks [emoji106]

 

[Uheat - Keith]

Same as all the guys above.

All my quotations come with the following text:-
After the Mats are installed a powdered flexible self-leveling compound is used to cover the underfloor heating at approximately 6mm in total not in addition to the 3.9mm cable thickness,
A powdered flexible tile adhesive is used to fix the floor finish.

Warm regards< Keith at Uheat.

 

[Dave]

IMHO , a 2 part slc isn't required ... Weber floor flex will suffice...

 

[radim]

i dont SLC small floors. tile directly on wire.
btw what do you use to keep expansion gaps around perimetre?

 

[tim000]

i dont SLC small floors. tile directly on wire.
btw what do you use to keep expansion gaps around perimetre?

the floor level is a little out so the SLC should save me on adhesive and the added benefit of reducing risk of nicking the heat cable with the trowel. I was going to put Silicon around the perimeter of the floor to prevent the SLC from running down the edges of the backer boards. in honesty I hadn't considered expansion gaps but the Silicon should allow for this?

 

[tim000]

Hi

 

[peterparker]

When I had my bathroom done, tile adhesive ( 50/50 mix of Mapei keraquick and latex plus) was used to cover the ufh. Is this ok or has the work been done incorrectly?

Thanks