Which one to chose: Celotex PL4000 and Knauf XPS Laminate Plus?

[John89]

The 1st floor kids' room is very cold. Two cavity walls with no additional insulation.
I am thinking of insulating it from inside using either Celotex PL4000 37.5mm and Knauf XPS Laminate Plus 27mm.
Which one should I chose?
1) which one has better heat insulation?
2) can both be installed using plasterboard adhesive foam?

thanks in advance!

 

[phatboy]

Of the 2 poor choices, the Celotex has more insulation on it, of equivalent R value.

But it's still insufficient, you should get one with 50mm insulation (62.5mm overall) at least. The greatest cost is the labour and decoration, so you may as well get a decent amount of insulation up there.