Low profile wet underfloor heating question

[surfstar]

Hi,

Im just embarking on a house refurbishment of a property I have bought. The house is a 1960's 3600sqft and has 6 beds, 3 baths and 2 kitchens over 4 floors.
I plan to have the hot air heating system decommissioned and have new wet underfloor heating installed throughout. Its likely that I will be using Wunderfloor heating as they seem pretty decent and are well priced. They offer a low profile solution that easily retro fits to existing properties (similar to Nu-Heat). This works well for half of the property but the two floors which have concrete slab I have concerns on the efficiency. How can installing a low profile solution direct on slab work efficiently when it is recommended there be 500m insulation normally? I don't want to embark on a low profile solution if its going to be inefficient!

Ideas would be appreciated.

 

[albatross]

It's a compromise but will be better than radiators. The nu-heat low profile stuff has polystyrene floor plates and alu spreaders so the heat goes where you want it. Just crack on with it.

 

[Ermintrude]

Those spreaders are pants. Much better with biscuits method

 

[albatross]

biscuits?? yummy! but really I'm not familiar with the biscuit method? Is it not a bit crummy! hahahaa

 

[lame plumber]

as you say, on a slab thats there it wont work very well, Ive seen folk remove and relay an old slab to do it properly, hassle but if your going to live there for the next 20 plus years, worth it

 

[Ermintrude]

More like a biscottie. If you have 8" joists

From bottom of joist 2*1 screwed onto side of joist (screws at 450) then 100mm celotex resting on battens, then a pipe laid in and clipped and then a weak and dry soft sand and cement screed, level with top of joist screw nail or glue boards or ply down. .

Lightly compact screed to increase density. Red sand is the most dense as it's clayish. Foundry sand is amazingly dense.

If smaller joists use thinner insulation / if less than 50mm use a 12mm ply base ontop of the battens before insulation.

 

[dancinplumba]

More like a biscottie. If you have 8" joists

From bottom of joist 2*1 screwed onto side of joist (screws at 450) then 100mm celotex resting on battens, then a pipe laid in and clipped and then a weak and dry soft sand and cement screed, level with top of joist screw nail or glue boards or ply down. .

Lightly compact screed to increase density. Red sand is the most dense as it's clayish. Foundry sand is amazingly dense.

If smaller joists use thinner insulation / if less than 50mm use a 12mm ply base ontop of the battens before insulation.

All well an good, but the op is asking about lo pro on existing uninsulated concrete slabs

 

[Ermintrude]

[Q UOTE=dancinplumba;609233]All well an good, but the op is asking about lo pro on existing uninsulated concrete slabs[/QUOTE]

Only two of them! Rest are timber?

 

[dancinplumba]

Oh and insulate, insulate, insulate, without it your underfloor won't heat as you require. In other words, you will be cold

 

[dancinplumba]

[Q UOTE=dancinplumba;609233]All well an good, but the op is asking about lo pro on existing uninsulated concrete slabs

Only two of them! Rest are timber?[/QUOTE]
Yes but those 2 are the ones the op is most concerned about ! !
PS don't need to shout ! ! ! !

 

[dancinplumba]

Oh, and I too like biscottie method

 

[Ermintrude]

Space quilt . Equivalent of 75mm of celotex but equivalent price of 440mm!!

 

[mutley racers]

space quilt?

 

[Ermintrude]

Like supaqiilt but for under floor