Phil L
wibbled on Monday 28 September 2009 22:27

... wrote:
I am in the process of renovating a small hairdressing salon.
It is having underfloor heating installed, approx 100 metres of
pipework over an area of 24 square metres.
The existing concrete subfloor will be sheeted with 25mm jablite
insulation with the UFH piping clipped onto it.
The cement screed will then be laid over the pipework to a total depth
of approx 30mm. With 18mm hardwood flooring laid on top of the
screed.
Everything seems to be straightforward, except for the screed, i would
like to mix rapid set cement & sand with a lot of water to create a
mix with a fluid consistancy to enable the mix to flow easily and
find its own level without much work with a float.
question is: Would mixing sand and cement to a very fluid state set
well enough to form a level enough surface to lay hardwood flooring
onto? Tounge and grooved Glued not nailed!
Thanks

30mm of anything over jablite won't last 2 minutes regardless of strength
or consistency - you need more thickness on the screed


I agree. It won't last 5 minutes. The research I've been doing suggests 70mm
at least over celotex.

I'm not even sure an SBR screed would cope with that thickness on a flexible
base AND UFH.

The two other options worth considering a

a) A flexible pourable compound - try phoning F Ball and other makers and
see if they rate anything for this. Going to cost though...

b) Have a look at www.floorheater.co.uk. They sell UFH jablite foil covered
panels with pre moulded pipe grooves. Their installation method is to stick
that down with adhesive then tile direcly over using a class S2 flexible
tile adhesive.

HTH

Tim

--
Tim Watts

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