Pitched Roof Insulation

[Geraud]

Hi there, not a specialist (mechanical Engineer)

I am proposing to insulate my self build extension pitched roof (ventilated, warm deck) as follow

150mm Kingspan Therma TP10 between the rafters (225m rafters) and 50 mm Kingspan Therma TP10 under the rafters.

The reason for this is that i have a stock of Kingspan TP10 in 100mm and 50mm.

Before i try to force this onto my BCO (my building plans indicate 100mm Kingspan K7 between rafters and TRI ISO insulation below rafter), do you think it will meet the requirements in terms of U value?

My BCO already said it would be happy with 125mm of Kingspan K7 between rafters and 25mm of Kingspan K7 below...


I know this mean U value calcs but as i said i am not in my element here...

thank you for your help

Regards

 

[freddiemercurystwin]

Any BCO would have to be a dope not to accept that alternative, it exceeds requirements. TRI ISO is pointless anyway.

If you really want to do some number crunching then google Celotex U Value Calculator, Celotex is for all intensive purposes identical to Kingspan so the results will be the same for Celotex as Kingspan.