What sort of PIR for warm roof - Confused

[whiskeyfrank]

Have a warm roof being built but really confused as to what type or PIR, do I need roof specific? Most stores cell normal celotex etc as suitable, but apart from Kingspan themaroof which is expensive and seems to be for bitchumen I cant find anyone that sells a specific flat roof PIR. celeotex say GA4000 is OK?
Its having an EPDM roof.

any ideas?

 

[Fred Blogs]

I would ask the people building the roof. I assume they are roofers and should know what they are doing although that might be a big ask in this day and age of "tradesmen."

 

[whiskeyfrank]

carpenters building roof structure, epdm contractors coming nextsdo dont have a reliable source as such!

 

[noseall]

Have a warm roof being built but really confused as to what type or PIR, do I need roof specific? Most stores cell normal celotex etc as suitable, but apart from Kingspan themaroof which is expensive and seems to be for bitchumen I cant find anyone that sells a specific flat roof PIR. celeotex say GA4000 is OK?
Its having an EPDM roof.

any ideas?

I'd be more concerned with the thickness, how it is supported, how it is fitted and that the falls are adequate. As long as you achieve the correct value for heat loss and it is fixed and supported correctly, then what ever PIR the suppliers stock. Most builders merchants are keeping up to speed with the latest regs and are stocking 150mm and above for roofs etc.

 

[robinbanks]

Are you asking "what is the difference between Celotex GA, TB, XR and CW, and which should I use for my roof?" ?

No significant difference, technically, only physically. TB is thin, GA is thicker, XR is thickest. CW is shaped differently so it can be installed a particular way round on a cavity and improve moisture defence

Some minor variations on themes exist and you may find e.g phenolic boards that are fractionally better insulation-wise but all PIR/PUR are much of a muchness and work well

Use whichever is cheapest and easiest to work for the sizes you need. Seconds And Co may be able to provide you with usable boards for less

 

[cdbe]

You can get PIR with 6mm* ply bonded to it for the likes of EPDM etc. Like most of these "wonder" products the price is probably twice that of the separate components.

*It does make you wonder why these roofs are commonly decked with 2 layers of 18mm OSB.

 

[noseall]

You can get PIR with 6mm* ply bonded to it for the likes of EPDM etc. Like most of these "wonder" products the price is probably twice that of the separate components.

*It does make you wonder why these roofs are commonly decked with 2 layers of 18mm OSB.

We don't bother with Pearldeck now. We fit a layer of 12mm OSB straight onto the furrings, lay insulation, then another 12mm layer on top.