Joining new hot roof to existing cold roof

[jayc89]

Original house has a cold, hipped roof, in one corner, it juts out where an extension was built, to create a gable end. You can just about make out what I mean here;

 

 

We want to convert the gable end section into a hot roof, part of it will be used for storage (possible MVHR unit etc) and the other will be vaulted. 

 

I'm sure our Architect has it all in hand, but for my own curiosity I tried to figure out how you would typically join 2 roofs like this, but couldn't find any obvious details.

 

Is this going to turn into another can of worms? 

[JohnMo]

If you can draw a solid line without breaks through the insulation, then everything is ok. If you can't you will have a big cold bridge.

[jayc89]

25 minutes ago, JohnMo said:

If you can draw a solid line without breaks through the insulation, then everything is ok. If you can't you will have a big cold bridge.

 

That's kinda my concern. The gable end loft space is accessible via the hipped roof loft space, so "something" would need constructing there to separate the two.

 

We'd be running PB up to the rafters in the gable end anyway, as it would be a vaulted ceiling, so presumably that could be stud work, PIR, taped to the warm roof detail finished with PB like standard?

 

That would probably also give us good access to a service void beneath the ridge beam for ducting, lighting etc.