best bang for buck on a big roof

[Buzz]

Reading another thread here today about fabric first i thought i would ask opinions on the most cost effective way of insulating my roof . 

It is a bit of a monster at 360m2 , i will have 225 deep rafters at 600 centre's  attic trusses, i know the simplest way would be to 150mm pir between and 50 underneath but with the cost coming in at 8-9k for the board then fitting any other inventive / cost effective way to get to 0.14 for less ?   

[Oz07]

Earthworm the frame fit stuff

[Russell griffiths]

I’ve got 200mm of knauf omni fit in between  my rafters and 70mm pir under for 0.14 

 

far easier to fit than cutting all that pir. 

Edited March 14, 2021 by Russell griffiths