Exposed cavity in roof space

[Radian]

I think I may have found why there is such a howling gale in my empty cavity walls  ?

 

That's the view from up in my loft looking down an internal gable dividing the house in two. The trusses sit on the wall plate on the inner leaf, then there's a 70mm empty cavity, then the blockwork laid flat to make up the width of the external wall which, on the exposed external elevations, is 70mm block and 150mm sandstone. For context, this is what the wall looks like when viewed from a bit further back....

 

 

The other side of that triangular wall is the vaulted ceiling of my hallway. I had never pulled back the fiberglass insulation before so didn't realise the cavity was open to the ventilated roof space. The total opening to the outside air provided by the eaves vents amounts to 0.5m2 and it gets very draughty up there. How much air movement there's been is evidenced by the blackened ends of the insulation where it was flopped over the wall plate. That's 25 years of traffic fumes I guess ? - even though we live in a rural area.

 

The rest of the cavity above the external walls is closed with a green plastic sock filled with insulation stuffed in between the inner and outer leafs. Why they decided to break with that idea when they got to the internal part of the wall escapes me. Maybe they were stuffing the cavity from the outside while up on the scaffolding. Anyway, the interior of my house is on both sides of that gable wall and the cavity makes a fine chimney to circulate freezing cold attic air into the heart of the house.?

 

Some day we'll get all the cavities pumped full with Walltite or Icynene but until then I'm up for suggestions on what to do with this particular gap?

 

I'm already in the process of going around filling the gap between the dry lining and the ceiling plasterboard with squirty foam. This gap has been exposing the back of our 'plasterboard tent' to the outside air as well. No wonder the inside walls can feel freezing to the touch. It was when pulling back the pink fluffy stuff to do this job that I made the discovery about the cavity.

Edited January 29, 2022 by Radian