We've engaged Andrew Gill, a CAT AEES graduate to assist with overseeing the fitting of insulation and air-tightness tapes, as this is beyond my expertise (I'm mainly focused on building services), and Andrew has first-hand experience of superinsulating a house in Manchester (see https://sites.google.com/site/lowerenergyterracedhouse/ for Andrew's very well-documented project).

The builders are almost at the point of being ready to start insulating the roof, so Andrew was on-site today going through things with them, and advising me of the (very expensive!) tapes and sealants that will be required - which I am to purchase directly.