ufh mat over 25mm ply. Need insulation boards?

[aflemi]

I haven't laid ufh on suspended floor for a while, just wanted to check procedure. Have lifted old floor boards as rubbish, plan to lay 25mm exterior ply onto joists then 160w ufh mat, fibre slc and tile with mapei keraquick with latex plus.
Tiles are 20mm X 90mm wood effect 10mm porc. Anything I've missed?

 

[Dougs Third Go]

obviously check there's enough noggins to get zero deflection, then yes, I'd use 6mm insulation boards. I'd be inclined to use wbp rather than plain old exterior ply too. I'm assuming the tiles are 200mm x 900mm lol!

 

[Uheat - Keith]

Same as Doug above.


6mm Marmox insulation boards before 160w/m2 mat.
As called construction boards.
Always powdered flexible tile adhesive - powdered flexible self leveling compounds.

Warm regards,

 

[Stef]

Same as Doug above.


6mm Marmox insulation boards before 160w/m2 mat.
As called construction boards.
Always powdered flexible tile adhesive - powdered flexible self leveling compounds.

Warm regards,

I've a job to price up Keith,
It's on a concrete floor & the client wants ufh but I've got a height restriction of 20mm.
Can you tell me the difference between running cost wise of a job with 10mm insulation boards v a job with ufh straight onto a concrete slab?

 

[Qwerty]

I've referred customers to this before Stef....

Broken Link Removed

Floor Heating Cost Calculator | Warmup - http://www.warmup.co.uk/uk/underfloor-heating-costs.phtml

 

[Stef]

Cheers Geoff..

 

[Uheat - Keith]

Good morning Stef,
Never seen any official report on this.
With boards any system will be approx 90% to 100% good.
Without board, this will only be approx 85% to 95%.
So many other things in the mix. Internal and external walls, ceilings, windows and doors all come into it.
The main thing is, the better the insulation, if you can use it, the better the system will work.

Hope that is of a little help.
Warm regards, Keith