A pitched ceiling 8M long, 5M to apex, room width 3.6M. Apex to 0.6M height vertical face above eaves is at a guess 4.8M. The pitch is steep, to the right faces directly south and the sun is uninterrupted by obstacles. In the winter the same face is subject to wind at an angle, only partially interrrupted by topology, you notice it in both seasons. It seems flat roofs do have some advantages. There is mineral wool between the rafters with a Tyvek barrier, all circa 2002 and on the inside 12mm plasterboard fixed to the rafters and skimmed. I worked out on the back of a cig packet that 50mm PIR faced with 11mm plasterboard would alleviate the worst.
So I want to avoid taking out the plasterboard as I have a strong dislike of mineral wool, it irritates my skin with a vengeance., long after it has been near me. I am hoping not to bury the principal rafters or the queen posts, 50mm plus plasterboard would not. No I don't want to suspend a ceiling from the obvious place.
Can this be done without causing the existing plasterboard to become dank; without removing it?

So I want to avoid taking out the plasterboard as I have a strong dislike of mineral wool, it irritates my skin with a vengeance., long after it has been near me. I am hoping not to bury the principal rafters or the queen posts, 50mm plus plasterboard would not. No I don't want to suspend a ceiling from the obvious place.
Can this be done without causing the existing plasterboard to become dank; without removing it?
