Insulating behind soffits

[datadiyer]

Hi all,
In the attached pic, how do I insulate the gap in the corners? The other side of this gap will be the soffits and fascia which may be vented or not (I don't know yet), but there's a heck of a draft coming through it. I know there will be plasterboard covering it but surely that would create a cold spot? It's a cold roof construction.
Cheers.

 

[Cavester]

Expanding insulating foam?

 

[datadiyer]

Thanks Cavester,
That was one of my thoughts, but wouldn't it need PIR like the rest of Insulation? But that would mean installing it from the outside before soffits/fascias are fitted. Would that be the norm do you know?
Cheers.

 

[Cavester]

Ideally PIR would be the most efficient, however if this isn't possible then at least expanding foam will prevent the drafts.

I don't suppose you could pack it with loft insulation could you? Just keep pushing it in until full.

 

[Jordabro]

Use Soudal Genius insulation foam and spray it into the gap, leaving it to expand and then doing it again so that its nice and thick in their. The excess that expands out of the gap can just be cut away. If left you'll get a cold spot along there and condensation as a result. I've not long just had to do this after replacing a ceiling.

 

[datadiyer]

Thanks Jordabro,

Got myself 3 cans of Soudal yesterday from Screwfix, seems like just the job, cheers.