Dormer dwarf/stud wall insulation - confirmation/advice (with pics)

We’ve been working to insulate the eaves / void area of my semi detached 1970s dormer. The area won’t be used for storage so I’m insulating the dwarf/stud wall and 1st floor/ground floor ceiling (rather than the rafters).

The wall is foil faced plasterboard on 75mm studs. I understand that the foil acts as a vapour control layer so where missing or damaged I’ve patched with foil tape or plastic sheet. Between the studs I’ve added 75mm rock mineral wool batts, seen in the pictures.

The space is very drafty from the eaves, feeding into between the rafters above the wall (which will remain open). I plan to further improve the insulation by adding a layer of 75mm celotex insulation board. We’ve already done the most difficult (narrowest) area under the window and plan to do same for the the remaining area.

Cabling has been routed through trunking to prevent overheating.

I’m wondering if I’ve made / am making a mistake in fully encasing the studs in insulation though. I read elsewhere that timbers need to breathe. I have the vapour control layer, but if any moisture gets through, it won’t be able to escape as celotex is not permeable, though rock wool is.

If I fully surround them, is there a condensation risk?

 

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