Insulating a pitched roof ( new extension)

[Mrpink]

Hi I'm in the process of having a extension build on the rear of my property, it's 7metres wide and 3 metres in the length, with a pitched roof of 17.5 deg.
The rafters are 8/2 and I'm in the process of insulating them with kingspan but was not sure whether to put the kingspan all the length of the rafters so it will pass over the cavity and into the soffit??? Or should I only butt the kingspan up to the wall plate?? Any help would be much appreciated

 

[freddiemercurystwin]

Your roof insulation needs to snugly meet the wall insulation, to complete the insulation bubble, often shoving some Rockwool or similar in that awkward space whilst keeping a gap beneath the membrane is the way to go.

 

[Mrpink]

Thank you😄😄😄😄