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PIR variations


Big Neil

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So does anyone understand why within a given manufacturer for PIR, they have different named products for different products. For example Celotex GA4000 (4075) is not suggested for part fill on cavity walls, but can be used in UFH and is described as general purpose PIR sheet. It is the same compressive strength as another of their products X-somethinh or other, which comes in sheets which are a fifth the size, and that one is not recommended for UFH applications.

 

Is PIR not just PIR?

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PUR and PIR may have slightly different chemical compositions depending upon application. Flat roof products for example face much more difficult conditions 'in use' compared to say a flooring application. The facings may also be different. What you see as a 'foil' face may have many different layers from a simple single layer to 11 layers or more depending upon application. Specific products based on the above variations may also be BBA approved for a particular application.

 

An alternative view is it's all marketing and sales hype and the products are actually the same!

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4 minutes ago, ADLIan said:

Flat roof products for example face much more difficult conditions 'in use' compared to say a flooring application.

 

Interesting comment. Could you explain this a little more? (My planned house will have a big flat roof, hence my interest.)

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On a very simple level product used in flat roofing has to cope with temps varying from say -10 C to perhaps 80+C and the foam/facings have to be formulated to cope with this. Flooring, cavity wall and 'general purpose' PIR products will never be subject to this temp variation. (Individual manufacturers may be able to offer more detailed info on the make up their products). Bottom line is the products are optimised for the application they are made for - hence swapping products/applications or using second grade product may lead to problems.

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Interesting idea on the chemical composition/facing front. So if one were to find a product, again lets say a celotex product for the sake of argument which was suitable for use; as UFH insulation below a screed, as part fill cavity wall and between rafters in a pitched roof, does that mean it would perform worse in one area, i.e. would have better insulating properties in the wall but have less compressive strength or whatever?

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The thermal conductivity will be whatever the manufacturer states and is backed up by CE marking, the DoP and perhaps BBA certification. (Note post Grenfell Celotex were guilty of over stating both thermal and fire performance of certain products and I believe had BBA certificates suspended). The compressive strength may vary depending on application and if load bearing or not. You would need to check with the manufacturer for exact values of certain physical properties but they may not be forthcoming with very detailed (commercially sensitive?) information.

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I probably haven't been too clear so my apologies. I just don't understand why if PIR is PIR is PIR, why if you have two different products whether from the same manufacturer or not really, with lets say the same compressive strength, both foil face which most of them appear to be, same thickness etc etc, how one could be for one application and the other would be recommended for something else.

Is it a bit like how well done you have your fried egg. they're still a fried egg but a firmer one is better suited to an egg bap where a soft one is great on a fry up?

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  • 3 years later...

Thought I would stick a post on the end of this as I have just been given a good price for PIR sheets that are marketed for pitched roofs for fitting on my floor, and looking at the manufacturers specifications for there floor grade sheets I cannot see the difference!

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