New Extension and Insulation

[leedsit]

Hi,

Im having a nightmare in getting insulation for my extention(Roof). Part is flat and part is sloped. The archi is specifiying Kingspan K11 at 120MM for the flat roof I have hunted high and low for this but couldnt find anyone who could supply. Now going for Celotex TD4000 126mm but this seem just as rare and expensive. Building control say if thats what the Archi states, I need to use it. What official criteria do I have to hit with this? Im stuck in a rock and hardplace between building control and the designer. Is there any reason why I cannot use cheaper version to the same thickness?

Cheers, Lee.

 

[freddiemercurystwin]

You don't need to use one layer of 120mm you can use 2 layers of 60mm or 1 @ 40mm + 1 @ 80mm. Provided it adds up to 120mm overall it will comply.

Often if doing a pitched roof you would use say 100mm between the rafters and then a continuous layer of 20mm beneath.

 

[leedsit]

You don't need to use one layer of 120mm you can use 2 layers of 60mm or 1 @ 40mm + 1 @ 80mm. Provided it adds up to 120mm overall it will comply.

Often if doing a pitched roof you would use say 100mm between the rafters and then a continuous layer of 20mm beneath.

Hi,

Thanks for the reply, it does state on the drawings to use Kingspan 37.5mm Dry-lining(K18) on the pitched part of the roof internally.

Instead of using Say 60mm TR31 and another 60MM TR31, to save both layers having Ply wood, would it be acceptable to use a 60MM TR31 then another kingspan product thats also 60MM thick? It seems the thick products (over 90mm) are hard to get hold off and I dont want to spend £600,£800 quid on insulation for the inspector to reject it(or am i being to paranoid?)

Cheers, Lee

 

[freddiemercurystwin]

BTW Kingspan K11 is not even available in 120mm thickness. If you read the trade lit http://www.insulation.kingspan.com/uk/pdf/k11.pdf you will see that where more than 90mm insulation is required they recomend that a packer is used of the appropriate thickness, the packer being Kingspan TR27 http://www.insulation.kingspan.com/uk/pdf/tr27fm.pdf so no need to use TR31 at all really.

Has to be said though that your designer has been paid to provide you with this kind of information and should have made it clearer on his drawings.

 

[^woody^]

You will find that any double foil wrapped insulation that looks like kingspan will perform near enough the same, and the BCO will just see the silver foil, and might just check the thickness and that will be it.

TBH though, the BCO might not even bother visiting to check the insulation - he will check the roof structure, but the next inspection may well be the completion one

 

[Heretohelp]

You will find that any double foil wrapped insulation that looks like kingspan will perform near enough the same, and the BCO will just see the silver foil, and might just check the thickness and that will be it.

TBH though, the BCO might not even bother visiting to check the insulation - he will check the roof structure, but the next inspection may well be the completion one

You could risk it, but some BCOs do check. Go back to your architect. Celotex do a handy free Uvalue calculator on their website.