Today Ryan and I got one quarter of the rafter sheathing panels up.
Each panel is attached with about four 3 1/2 in. standard construction screws with special 1 1/4 in. washers to give the screws better grip on the otherwise soft foam polyisocyanurate insulation boards.
The foam boards overlap the Tyvek on the walls, providing a drip path all the way to the floor.
The tops of the sheathing boards are lined with foil to provide a radiant barrier and the seams are covered with a foil HVAC tape to avoid water, vapor and air infiltration
Ryan volunteered to navigate the tight space above the ceiling to drive screws and apply tape.
Though the boards fit together pretty well, the remaining small gaps between them and the rafters will be sealed up by closed cell spray foam from beneath.
The space already feels and sounds different with the rafter sheathing up.
Trevor Parscal's Studio 
