Minimum depth

[ts276]

I am considering retrofitting UFW in my kitchen, which is around 5 square metres, uninsulated solid concrete floor (not suspended). If I remove the existing sand and cement screed I should have about 6cm depth to work with.  Any deeper would mean cutting into the underlying concrete slab or raising the floor level, neither of which are practical. The UFH would be used intermittently for comfort (walking barefoot), helping to dry the floor and prevent damp underneath and behind the kitchen units. The room will continue to be heated using radiators.

 

Is 6cm enough to install UFH?

 

Should in use a wet or electrical system ? I already have wet UFH in other parts of the house, so I should be able to tap into this.

 

Is it worthwhile and practical to install a very thin layer of insulation underneath the UFH if space allows and what type should I use considering the limited thickness?

 

Are there any precedents and guides for using vacuum insulation panels in this application?

 

[Redbeard]

Any insulation better than none at all, but 60mm for the 'whole sandwich' just seems far too minimal to me. Others may disagree...

[SteamyTea]

The calculations are pretty simple to work out the thermal losses to the ground.

If we assume that ground is at 10°C and the room at 20°C and the insulation has a k-value of 0.04 W.m^-1.K^-1, then:

 

U-Value = 1 / (l.k) where:

l= insulation thickness

 

U-Value = 0.7 W.m^-2.K^-1

 

So losses with a 10K temperature difference is 7 W.m^-2, so an extra 35 W for the full 5m²

 

So very little is lost to the ground.

 

Now the problem is really how hot will the floor actually need to be to heat the kitchen.