Insulating Existing Loft Room

[Copse Road]

Hi our early victorian terrace has a lathe & plaster room in the loft with no insulation. I can access the eves to insulate behind the l&p walls as well as a portion of the rafters (up until the angled portion of the room).

Is it worth me insulating the parts of the roof that I can access? I'll have to leave the apex of the roof/bit above the ceiling in the room.

Thanks!

In my sketch, brown = roof outline, blue = lathe & plaster room, green = areas I can insulate.

If I do, I'll be leaving the 50mm air gap.

 

[noj]

No benefit in insulating the angled bits of roof (I think).

But the horizontal and vertical bits would make a difference.

Caveat that with making some bits warmer other bits may be more prone to condensation...