advice on fixing stone over nu heat panels

[jonnyc]

i am quoting to do a job where the following spec has been proposed over an existing rough concrete floor.
the reason for this system is because there is only 65mm to play with at the max from concrete to finished floor.

i have not specified this .it has been put to me .
wondering what you think or any better ideas.

level off concrete from highest point with latex.
contractor to loose lay kingspan 20mm optim R boards on to level flat subfloor prepared .
then dpm .
next 15mm thick nu-heat lopro10 gypsum boards with 10mm water pipes set in boards.
followed by dural ci matting stuck down with mapei elasto rapid.
stone stuck down with mapei elasto rapid.

what do you reckon?

i have to base this on the base having been latexed being dead flat and level.

any other ideas welcome

 

[Time's Ran Out]

What keeps the 15mm lopro 10 down?
Sounds like its floating kingspan, dpm and floating lopro .

 

[jonnyc]

thats exactly what it is which is quite worrying.
the reason why the client likes the optim r kingspan is that although it is only 20mm thick it has similar insulation values as a 60mm normal kingspan board.
when i have seen a similar problem before , the contractor has screwfixed battens in to concrete and levelled battens up with packers to say minimum 20mm.
contractor has then laid insulation boards which have water pipes set within board between battens.
but these insulation boards dont have the insulation properties of the kingspan optim r .
in this scenario we are then at a point when min 18mm min plywood can be screwfixed in to battens .
this is similar to between joist water systems overlaid with ply wood that i have fixed on to for last 15 years.
difference was few years back schluter used to guarantee ditra over plywood over water system.
now they do not .
but dural do which is strange and not so strange because i think schluter have their own low build up system which i had never heard of till today.

 

[One Day]

i think schluter have their own low build up system which i had never heard of till today.

They do indeed have a very low height system, not sure if it's available yet but worth ringing and checking.
Finally someone is doing this right in the UK.
Now just that little issue of "price" to get round.....!

 

[The Legend; Phil Hobson RIP]

thats exactly what it is which is quite worrying.
the reason why the client likes the optim r kingspan is that although it is only 20mm thick it has similar insulation values as a 60mm normal kingspan board.
when i have seen a similar problem before , the contractor has screwfixed battens in to concrete and levelled battens up with packers to say minimum 20mm.
contractor has then laid insulation boards which have water pipes set within board between battens.
but these insulation boards dont have the insulation properties of the kingspan optim r .
in this scenario we are then at a point when min 18mm min plywood can be screwfixed in to battens .
this is similar to between joist water systems overlaid with ply wood that i have fixed on to for last 15 years.
difference was few years back schluter used to guarantee ditra over plywood over water system.
now they do not .
but dural do which is strange and not so strange because i think schluter have their own low build up system which i had never heard of till today.

Is this like the Polypipe system Jonny? they say their boards can be loose laid, but I have always insisted on them being glued and screwed.

 

[jonnyc]

Yes very similar Phil.only difference is that this kingspan is only 20thick and it worries me that it may flex .the key is getting the concrete dead flat before they do the heating.as you know it's not just a matter of pouring umpteen bags of latex on floor and watch it miraculously self level as most contractors believe

 

[jonnyc]

It's been available for 9 years but I have never fixed on it.with their method could use the 20mm kingspan,then 23mm plastic tray,8mm sand cement screed on top!!!!then ditra plus tile and adhesive.this gives 81mm total build up which exceeds the 65mm we have to play with

 

[tilerbarry]

There seems to many loose layers in the substrate build up for my liking! Walk away would be my advise!!

 

[jonnyc]

after re looking at what height there is to play with i believe there is now 85mm.
therefore the kingspan optim r 20 mm
schluter bekotec f 23 mm
8mm screed over top bekotec 8 mm
ditra 4 mm
adhesive 5 mm
stone 25mm

total build up 85mm

this looks like a system i can guarantee my stone on.

anyone fixed on top of this or seen it at a schluter course

 

[bugs183]

Hi jonny.
I've fixed onto the Bekotec system and it works a treat. I'd certainly fix on it again. The proposed system sounds way too dodgy mate, i've walked away form several jobs using a similar system, flexes way to much.