What is the minimum depth of SLC over insulated boards?

[On one]

As above......I have 18m2 of floor to bring up by 30mm to the same level as an adjoining floor. Insulated boards would seems the obvious way to go followed by SLC.
But to work out the depth of the insulation I need, I need to work backwards from the minimum depth of SLC over the insulated boards, which is?????

 

[Dave]

Depends on the brand of slc , most deep depth slc's that go above 10mm are min 2 or 3 mm ..

 

[On one]

At 2-3mm I would be worried about point loading issues.
Forgot to mention that once the sub floor is brought up to the correct level I would be tiling over it.

 

[Dave]

I would say 5mm

 

[CJ]

Found this stuff.

http://www.fermacell.co.uk/mobile/en/content/2418.php

 

[On one]

Found this stuff.

http://www.fermacell.co.uk/mobile/en/content/2418.php

Thanks CJ.
If I chose those boards I will definitely have to double board or give myself a bad back!
Availability and delivery might be a problem where I am located as well.
Cheers anyway.

 

[Rookery]

For simplicity I'd probably go 20mm board then 10mm Mapei Renovation Screed. Both readily available.

 

[On one]

Probably the route I will go down if the price is accepted. Not going to be cheap though.

 

[kaharrison9]

I just recently brought up a 46m2 anhydrite floor by around that depth.

I used 60 Marmox 20mm insulation boards fixed down with a 8mm trowel and also mechanically fixed with the Marmox dowels (300 hundred used). 4 mm thick SLC for the UFH and then made the rest up with adhesive.
Hit the thresholds perfect.
Marmox also do a 30mm board.
The 60 boards alone cost around £760 but customer well pleased.

 

[On one]

I did Check with Marmox tech dept and they advised the depth of the SLC on the boards was down to the SLC company's spec.
They also advised unlike you, that I didn't have to mechanically fix. I would do though,just to cover myself.
Out of interest Karl, what did you pay for your 20mm boards?

 

[kaharrison9]

I used ultra 2 part latex that goes from 2-10mm so within spec of the slc
With the boards I put a fine line of addy along the side of the edge before butting up.
Reason I used dowels to mechanically fix was it was an anhydrite and the boards are cement based so went down the route of twice priming then used keraquick and the dowels 5 in each board was just belt braces if any issues occurred with ettrinite.
Regardless of what type of screed if I did it again with 20mm I would without doubt use the dowels,the boards, addy, tiles, my labour etc made it a very expensive job and the dowels were 11p each so for £30 well worth the peace of mind and they did nip the board tight to the screed.
As well if it is a nice flat pourable screed you have a chance of a full bed of adhesive between the screed and marmox board which is fine but if it is not then wouldn't like the thought of any voids between the screed and boards.
I paid £12 a board.

 

[On one]

£12 per 1.2m x 0.8m?