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I am planning my extension. There is lots of marketing bollocks surrounding this topic, I have it under a wood floor on my 1st floor, backed by foil and rockwool, and it works very well. I had a manifold and control system with three extra loops installed to account for my kitchen and extension so I am ready to rock on that front.
It is ground floor, so it will be on a dpc/concrete slab, but then what?
Some people are saying 100mm insulation, lay pipes on top with some kind of fixing, then screed and then apply flooring (I am thinking slate). This sounds sensible to me, and cheap as you don't have to buy a "system" just the metalised pipe and some clips. Am I missing something?
Nope, that’s a good solution. We’re laying similar in our new place, there’s nothing too complicated about it.
That sounds about right. Screed floors are the simplest and most effective for UFH.
I'd recommend WundaTrade/Wundafloor as a supplier. Very keen prices, quality of the parts is good enough and backed by a warranty and they'll do your layout design and calculations for you.
Watch what type of screed you put down.
Some of the fancy anhydrite screeds dry at a rate of 1mm to 2mm per day dependent on thickness and cost a bloody fortune....
Yeah £14 to £26m2 depending on what you have. From basic sand/cement through to fancy thin liquid stuff. Not cheap!
Some of the fancy anhydrite screeds dry at a rate of 1mm to 2mm per day
So does Sand/cement. 1 day per mm thickness is the recommended drying time for screeds generally for floor finishes.
liquid screeds need to have the correct adhesive used on them as well, but they are great to tile onto, i've never tiled over sand/cement floors as level.
i'll be using sand/cement when i do mine as i can then screed it myself saving quite a lot but if i was having to pay for the screeding whichever i used it would be a liquid screed.
liquid screeds can go down thinner than sand/cement as well.
IIRC, we have 150mm of kingspan- pipe work- 100mm screed- slate. Works well, the slab holds heat nicely.
I am thinking slates -do they go down using tile adhesive then?
Yes - Try and get calibrated as it makes the laying much easier. Clean and seal the face before laying to aid clean up after grouting.
Anhydrite (poured) screeds to indeed require special adhesive, Anhyfix or similar. It's also very important to sand the laitance from the top surface before tiling.