Insulation under heating mat

[Fran Smitherman]

The Homelux Heatwave insulation board I saw on display in my local DIY store appears to have a core of pink polystyrene (1 centimetre thick) with a grey (fire-retardant?) skin to each face.  Is there a more eco-friendly alternative, along the lines of shredded newspaper insulation?  If so, would this need to be thicker than 1 centimetre?

 

Fran

[PeterW]

That is extruded polystyrene so 25mm is just to stop an element of heat loss. Shredded paper or blown cellulose would need 100mm or more.  

[Temp]

What do you mean by eco friendly? 

 

25mm of insulation isn't much to prevent heat loss. Building regulations for the floor of a new house suggest more like four times that.

 

If you want to improve the performance of the insulation it might be possible to use PIR insulation rather than polystyrene but what's going on top? Tiles need sufficient support. I suspect the grey coating might be fibreglass/cement for that reason?

 

Do you have solar panels or is electric heating considered eco friendly these days? I guess it's ok if you are on a renewables tariff.

Edited February 16, 2019 by Temp