Underfloor heating advice

[reflexboy]

Morning all
I currently have a Amtico covered suspended floor in my kitchen . I would like to install underfloor heating. I have looked into what is needed for 'wet' UFH and 'dry' electric UFH and although wet is far more efficient, because of my floor/sub floor I think electric will be the easier option for me.
My floor consists of 18mm green water resistant tongue and groove flooring grade chipboard across the joists with 100mm of Celotex insulation between the joists. I then went over the top of that with 6mm WBP plywood and laid the Amtico foor (vinyl tiles) over the top using the Amtico adhesive.
What is my best way of installing dry UFH? Obviously the existing floor covering will need to come up. Can I lay the UFH mats/elements directly on the chipboard and/or plywood or do I need anything in between? Also, once the heating mat is down, I'm don't think I can then spread the adhesive to lay another Amtico floor as the adhesive is spread about 1-2mm thick and the heating mat 'elements' are approx 3.6mm diameter.
Any idea of the correct way of doing this for the best results economically?

 

[tor_ake]

The UFH vendor surely has instructions for how to lay their particular product.

I will be adding UFH to my upstairs bathroom, and for that application, the UFH products available (in sweden) states they should be casted in a 8-15mm thick layer of screed. For joist floors, it should be laid between the joists on top of the insulation, with small notches in the joists so the heating cable can get through. Between the heating cable and the insulation there should be some kind of metal net (akin to chicken pen net).

 

[Mac1]

Morning all
I currently have a Amtico covered suspended floor in my kitchen . I would like to install underfloor heating. I have looked into what is needed for 'wet' UFH and 'dry' electric UFH and although wet is far more efficient, because of my floor/sub floor I think electric will be the easier option for me.
My floor consists of 18mm green water resistant tongue and groove flooring grade chipboard across the joists with 100mm of Celotex insulation between the joists. I then went over the top of that with 6mm WBP plywood and laid the Amtico foor (vinyl tiles) over the top using the Amtico adhesive.
What is my best way of installing dry UFH? Obviously the existing floor covering will need to come up. Can I lay the UFH mats/elements directly on the chipboard and/or plywood or do I need anything in between? Also, once the heating mat is down, I'm don't think I can then spread the adhesive to lay another Amtico floor as the adhesive is spread about 1-2mm thick and the heating mat 'elements' are approx 3.6mm diameter.
Any idea of the correct way of doing this for the best results economically?

HI.
As for your UFH, issues to be considered is the final covering (Amtico).
Usually a single core is the easiest/cheapest way forward. Warm Up do full kits with thermo controls, we use these (buying off a third party, much cheaper than direct) mainly under timber and tile.
But unless you screed a single core to dissipate the heat it would prolly have a adverse effect on your Amtico.
There is a system called Heat Pak which is a dry fit and made for vinyls. We have never used this as yet, so it's a suck it and see scenario...
Changing the Amtico to a solid finish (Tile / Timber) could work out cheaper all round.
Hope this helps.
Mac
Director of a Building Co.....

 

[reflexboy]

Thanks Mac, very interesting comments. I was trying to avoid screeding but as you say it could be cheaper to tile/time the top covering. Thanks again

 

[Dieselman]

Could you not use aluminium spreader plates instead of screed? You won't get the heat retention but will get an even distribution.

 

[Mac1]

Glad to help.
Any building related issues please drop me a line........

 

[Druk]

I fitted a Warm-Up kit in our shower room. It's laid on 20mm ply and is stuck down directly with a sticky tape and then screeded over with the tile adhesive. iirc the wire is about 2.5mm. How would you screed over that with Amtico adhesive and produce a completely uniform surface that wouldn't show the humps and bumps over time?
Also, the heat in the wire is dissipated across the floor via the screed.
Only thing I can think of would be to sink the cable into the ply with a router and flush it in with a fine screed.

What does an Amtico distributor say on the subject?

edit...if you choose a foil system make sure the joins in your substrate are stable. Our caravan has foil UFH and it's failed at a join in the ply floor obviously because of flexing.

My big problem with the Warm-UP kit is the complication offered by the control unit. AAAAGGGGHHH!!! It wants to know your size of shoe and store number before it will cooperate.

Does anyone know of a simple UFH control?




.

 

[Mac1]

Warm up control units are brill.....Read the destruction's....

 

[tippandy]

Hi, this is what i do for a living. Take up the amtico and the ply, Then lay 4 or 6 mm dukka board glued or screwed to the chipboard.Then lay the warm up cable taped down as mentioned earlier and if using normal tiles lay as normal,or if you want amtico laytex the floor and then the amtico.The dukka board is to mgive you the full benefit of the heating.If using normal tiles make sure the chipboard is well screwed down.

Andy.