Expensive Kingspan wall insulation vs cheap expanded polystyrene

[dominoman]

I have a loft room built many years ago that has no insulation at all. It gets very cold in winter.

To insulate I was thinking to place solid insulation boards between the vertical beams (if that's the right word). Should I pay full price?

There's an enormous price difference between the cheaper polystyrene boards, and the expensive Kingspan/Cellotex type boards. As it's a DIY job is it really worth the extra money. I'm not doing it for Building regs or the like, it's just to keep some more heat in.

Thanks for any views...

 

[jeds]

Kingspan PIR boards are usually about double the thermal value of poly boards. Maybe more, it depends on the type of polystyrene. So you'd need 150mm of polystyrene to give you the same as 75mm of Kingspan.

 

[Burnerman]

I'm paying around £30 for an 8x4 sheet of Kinspan equivalent, at 70mm thick. Foil backed, cuts and snaps with a Stanley knife.....thats my choice!
John

 

[cjard]

Were I you I'd check ebay for self builders looking to offload overspill. While collecting 18 rolls of acoustic wool off a guy from Cheshire at the weekend, he offered me 70mm kingspan boards at 15quid each. Alas, I didn't have a use for them so I declined, but they were a bargain. Also if this is in a loft and not requiring perfection getting the right seconds will be cheaper than polystyrene (when blinding ny floor level it turned out cheaper to use kingspan seconds than sand for building up)

 

[dominoman]

Great idea cjard. I'll take a look on preloved and my local facebook group