Underfloor with no screed

timod · 20-05-2014 09:12PM #1

Hi all,

I'm in middle of a refurb. We have installed some insulated polystyrene panels on the existing subfloor with a built in channel for the piping. There is a foil surface to diffuse the heat.

Something like this:
http://www.thesolidwoodflooringcompany.com/gluing-hardwood-floors-to-aluminium-spreader-plates-with-underfloor-heating-tc-238.html
Or
http://www.underfloorheatingdepot.co.uk/acatalog/overlay-and-overlaylite-installation-guide.pdf

My impression was that engineered wood could be installed directly over this, or perhaps with a thin ply, but any of the flooring guys I've spoken too don't seem keen, and want at least a few cm between the engineer wood and the pipework. (I'm caught for height, so a few cm is not an option!)

Has anybody any experience with a product such as this?

Thanks,

Tim

shane 007 · 20-05-2014 09:48PM

The main downsides of that design is 1) you have no thermal mass to store & dissipate heat & no thermal mass generally does not suit UFH and 2) timber is a natural insulator, thus poor at allowing the heat through it from the system to the room.

There are suitable designs on the market to allow a light weight mix suitable for timber construction floors & then a suitable floor covering can be applied to this.

timod · 23-05-2014 05:36PM

Thanks Shane.

I'm now looking at something like the fermacell 2e22 board. Seems to be designed for this purpose.
http://www.floorinsite.com/fermacells-underfloor-heating-system-provides-superior-results/

shane 007 · 23-05-2014 08:12PM

timod wrote: »

Thanks Shane.

I'm now looking at something like the fermacell 2e22 board. Seems to be designed for this purpose.
http://www.floorinsite.com/fermacells-underfloor-heating-system-provides-superior-results/

Yes I see that but where's the thermal mass. Basically it will heat like an on demand system but at lower temperature.
What is your fuel source?

timod · 25-05-2014 10:56PM

Hi Shane, I have a gas boiler for the UFH.

The rest of the ground floor is polished concrete, so has an inherent thermal mass, and works very well. It has been up and running for the past 6 weeks. It's just one room, south facing, that will have the wooden floor, and it's on a separate zone, so the yes, a responsive on-demand heat. (I'll probably be installing a stove in that room in the future also)

Tim

Underfloor with no screed

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