Insulating the walls

The walls also need insulating, and I have chosen 70mm Rectacel foil backed & faced insulation panels, to sit between the OSB external sheets, and eventually the plasterboard interior.  Although the roof hasn't been finished, it is now waterproof with the sheets and temporary cover, so I am able to make a start on cutting and fitting the insulation.  They need to be cut to a good tight fit.