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

.... 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

--
Phil L
RSRL Tipster Of The Year 2008

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

This space intentionally left blank...

.... 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.

Bit bllody thing 25mm. Id gor for 60mm if you can..

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.

Minimum depth is about 75mm for screed. You will crack that over jablite

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

I think frankly that unless I have missed something, you are in a
complete mess. Your insulation is too thin and so is your screed.

You would do better to use a suspended real wood floor and run the pipes
over more insulation between the joists.

Tim W wrote:
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.

still needs a lot of insulation under, though, if over a concrete slab.

Jolly nice for an upstairs room though, where heatloss downwards is not
such a big deal.


HTH

Tim

On 29 Sep, 10:33, The Natural Philosopher
wrote:
... 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 theUFHpiping clipped onto it.

Bit bllody thing 25mm. Id gor for 60mm if you can..

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.

Minimum depth is about 75mm for screed. You will crack that over jablite

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

I think frankly that unless I have missed something, you are in a
complete mess. Your insulation is too thin and so is your screed.

You would do better to use a suspended real wood floor and run the pipes
* over more insulation between the joists.



- Hide quoted text -

- Show quoted text -

Thanks for the advice... decided to forget about the cement screed and
recess spreader plates into the Jablite & fit UFH piping into it,
connected to a twin loop manifold, & covered by 9mm ply with the 18mm
oak flooring on top.

Tommy
wibbled on Monday 05 October 2009 23:24


Thanks for the advice... decided to forget about the cement screed and
recess spreader plates into the Jablite & fit UFH piping into it,
connected to a twin loop manifold, & covered by 9mm ply with the 18mm
oak flooring on top.

If you haven't bought your bits, www.floorheater.co.uk have exactly that,
ready made (foil covered jablite with pipe grooves).

--
Tim Watts

This space intentionally left blank...

On 6 Oct, 07:25, Tim W wrote:
Tommy
* wibbled on Monday 05 October 2009 23:24

Thanks for the advice... decided to forget about the cement screed and
recess spreader plates into the Jablite & fit UFH piping into it,
connected to a twin loop manifold, & covered by 9mm ply with the 18mm
oak flooring on top.

If you haven't bought your bits,www.floorheater.co.ukhave exactly that,
ready made (foil covered jablite with pipe grooves).

--
Tim Watts



I have most of the materials i need the foil covered recessed jablite
looks the business though, maybe next time.

Tommy
wibbled on Tuesday 06 October 2009 09:39

On 6 Oct, 07:25, Tim W wrote:
Tommy
wibbled on Monday 05 October 2009 23:24

Thanks for the advice... decided to forget about the cement screed and
recess spreader plates into the Jablite & fit UFH piping into it,
connected to a twin loop manifold, & covered by 9mm ply with the 18mm
oak flooring on top.

If you haven't bought your bits,www.floorheater.co.ukhave exactly that,
ready made (foil covered jablite with pipe grooves).

--
Tim Watts



I have most of the materials i need the foil covered recessed jablite
looks the business though, maybe next time.

OK.

BTW - I assume you are tiling over this. Don't forget that you will need a
flexible adhesive and flexible grout. I would go with Class S2 which is
more flexible than S1.

Mapei Kerabond + Isolastic works well for sticking tiles to flexible things,
but there are many other options. That's a slow adhesive (many hours
setting time) - there are super fast ones that can be made or obtained
flexible too.

For the grout, you'll be OK with Mapei Keracolour + Fugulastic liquid
instead of water, though there are again many other options.

Don't be tempted to be cheap here - the tiles or joints will crack,
especially with UFH.

--
Tim Watts

This space intentionally left blank...