Looking for 100mm and 25mm sheets of insulation

[NewToAllOfThis]

Hi,

I'm looking for 40 sheets of PIR 100mm and 40 sheets of 25mm insulation for the roof, are there any makes I should avoid.

 

Can anyone point me to where they have found the best price recently and the product used.

 

Will be looking for 150mm PIR floor insulation but not yet, again any recommendations as to what to use / not use.

 

Why are there so many different products from each manufacture, all seem to have the .022 uValue

[Temp]

9 hours ago, NewToAllOfThis said:

Why are there so many different products from each manufacture, all seem to have the .022 uValue

 

Because most are made same way from basically the same materials. Sometimes with modifiers to alter the density or fire properties.

 

Polyisocyanurate (PIR) is a modified Polyurethane. Typically around 0.022-0.028

Expanded Polystyrene is usually around 0.034

 

These figures are for a nominal 1m thickness of the material. If you simply scale the numbers for 150mm thick sheets they will be close to the makers spec for that thickness but can vary slightly due to surface effects.

 

Normally the 0.022 figure quoted for PIR assumes most of the gas used to make it has leaked out (eg its aged). So for the first 10 years or so it actually performs a bit better.

 

The main issue with rigid insulation is sealing gaps. Builders tend to just saw sheets to fit between rafters and I'm convinced that's where a lot of performance is lost. If I ever build again it will be a warm roof with insulation above the rafters so sherts can be butted together or perhaps using SIPS.

 

Lots of other data  here on different types of insolation...

https://www.greenspec.co.uk/building-design/insulation-materials-thermal-properties/

Edited July 31, 2021 by Temp

[CotswoldDoItUpper]

@NewToAllOfThis I’ve just done the same! Seconds and co (secondsandco.co.uk) seem good if you can wait the 5-15 working days and don’t mind adding the occasional bit of foil tape to make good.

google might be your friend but I found the best price was with my Jewson trade account and a bit of a haggle! 
Good luck!

[Olf]

On 01/08/2021 at 00:24, CotswoldDoItUpper said:

Seconds and co

I used them recently, waited only for a week for delivery, but this is because half of the wagon was mine: they send it only when fully loaded.

Quality was ok, considering it will end up in the floor and was nearly 20% cheaper than the next best (though brand new: insulationhub), I won't complain.

 

[NewToAllOfThis]

Tried Jewsons and Signa but they were not interested in offering a decent price. Search on line gave some good prices and then pushed for them to beat the competition and have got Cellotex 80mm at £34.00 and 100mm at 38.00 prices + VAT. Free Shipping.

 

[gc100]

For you reference this is what I paid a year ago:

 

170 sheets of 100mm -  £22.58+VAT

30 sheets of 120mm - £28.17+VAT

55 sheets of 150mm - £33.18+VAT

30 sheets of 50mm - £12.57+VAT

 

delivered. It came direct from the manufacture but deal was done via my builders yard