How to Insulate finished attic room that has a Dutch hip that connects the side attic

Lascaux

The roof of my house has a Dutch hip/gable adjacent to an original finished attic room:

The Dutch gable is not only open to the side attic…

… but it connects the two side attics:


This is an open channel and with a 14-gauge cable running through. The insulation appears to be falling out of the wall in places. I am planning the insulation for the finished attic room. How do I handle this Dutch gable?

Windows on Wash

Need another picture of the venting on the roof as well.

In short, insulate the kneewall with batting and rigid foam over the top, seal all the seams. Make sure that exposed foam is okay for code compliance in your area and use the proper foam to meet such compliance.

Pull the joist blockers from the under floor and seal them off with foam/caulking.

Insulate the floor where it meets conditioned space.

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Lascaux

I had a ridge vent installed when the roof was redone. I will be installing continuous soffit vents, and blocking the gable vent.

The air masses of the two attics areas, one on each side of the finished attic room, are connected by the space below the Dutch gable. How should this connection be addressed?