Grateful for advice on tiles - lime/slate stone or something thinner?

[TinyFlat]

Hi New to the forum and new to tiles and underfloor heating. Hope you will be able to take some time to share your expertise. Hoping to get listed building consent for a small conservatory - it will be 45 sq ft floor space - very smalll but all space is valuable where I am (London) and I have a 217 sq ft concrete patio which goes to waste most of the year. I was planning to resurface the patio in lime or slate stone (concrete would need to be levelled first as has sunk in places) and use the same flooring inside the conservatory so the look is uniform and seemless, which will appeal to the conservation officer. However, the stone is 20-30mm thick. I am wondering if this is a good idea or if I would be better off trying to find tiles that look like the lime or slate for use inside the conservatory but are ceramic or porcelain and so not as thick as the stone paving pieces outside? What is better for underfloor heating? I have contacted one company who when I told them said they would install 6mm inscreed heating cable plus a thermostat for £225 inclu VAT with labour to install it being £350 pd + VAT (they said one day) I asked if I should opt for a thinner tile and they then said said it wouldn't make a difference and the inscreed option was the cheapest option. Will ring other firms but wanted to hear thoughts here. I guess a thick stone will retain more heat but perhaps take longer to get warm? The space would only be used for at home working 2 days a week and maybe as a dining space so would need to have the potential for every day use but may not be used every day.

 

[Time's Ran Out]

Re: Grateful for advice on tiles - lime/slate stone or something thinn

My questions would be :
1) how thick is the patio substrate at present.
2) do you intend to put a dwarf wall at the base of the conservatory or is it a lean to type bolted to the base
3) I like the idea of the thick stone being inside and out.
4) the stone would take longer to heat up but will retain the heat longer and will absorb the sun better rather than reflect.
5) consider the stone floor output UFH cables of 200w per metre and it will heat up quicker - Thermonet do one.
6) could consider some insulation board first.
7) the cost of your UFH and thermostat seems ok and the labour for London may be just a bit on the high side unless it includes the screeding of the cables prior to tiling.
8) does the installation of the Ufh include the connection to mains supply by a qualified electrician (part P registered).

What part of the London area are you located as there are Tilers on this forum would could advise.

 

[TinyFlat]

Re: Grateful for advice on tiles - lime/slate stone or something thinn

Thanks
1 All I see is a concrete surface , grey and sunken in places where water pools so don't know more than this.
2 Unsure because this is a flat in G2 listed building and only at the stage of discussing designs with companies who have experience of dealing with conservation issues so not sure of final design.
3 Agree but am I being stupid expecting someone to cope with 20-30mm thickness (10mm variation) should I be buying in the calibrated at 22mm stuff?
4 Agreed
5 Will look at this - thank-you
6 Do you mean on the concrete base before starting? Any recommendations?
7 Don't know if includes screeding I presumed it did I will check
8 Again I need to check - thank-you.

In Paddington, London. Have made contact with one person who posts on here who is in Surrey, happy to hear from any locals

Great board - so much knowledge. Spent last couple of hours reading all about black limestone on here.

 

[Uheat - Keith]

Re: Grateful for advice on tiles - lime/slate stone or something thinn

Agree with all of 'Timeless John's' post/notes.

The only thing we would says is about the '6mm in-screed cable'.
We would class a system in 6mm compound as; Under-tile cable or mat with a cable thickness of between 2mm to 4mm, in a compound of between 5mm to 8mm. This is Direct Heating and warms up-cools down in a short space of time.
We would class an in-screed system as; In-screed cable with a cable thickness of between 6mm to 10mm, in a sand-cement screed of between 50mm to 80mm. This is Storage type of Heating and warms up-cools down over a long period of time. i.e. power in floor over night on E7, release slowly over the next day.
200w/m2 is great for a Conservatory with either system.

Warm regards, Keith.

 

[TinyFlat]

Re: Grateful for advice on tiles - lime/slate stone or something thinn

Thanks so much Keith, that is a useful distinction for me to be aware of and wasn't made clear to me when the salesman made his recommendation . Think the former option, i.e. something that heats up relatively quickly, would be better for me, as I won't be using the space every day.