Whats would be better Insulation?

[Mcneelyma]

100 xtratherm polysio or 120 mm kay-metzeler eps 70?

I have done some research but its new to me so i thought i'd ask the experts, am i right in thinking that the eps 70 is really only as half as good as xtratherm? What about price difference? U-value?

 

[^woody^]

Generally, efficiency for a given thickness of the rigid boards (lowest to highest)-

White - plain EPS
Yellow, pink, blue - Styrofoam, jablite etc
Pale yellow and foil backed - celotex, king span, xtratherm etc

 

[Mcneelyma]

Thanks for the info