The drywall has been completed, all walls are primed and ceilings are painted. Once the framing inspection was done by the local building inspector, we went directly into drywall because all of the insulation is within the Structural Insulated Panels. We save considerable amounts of time. There is also the advantage that you do not need to install polyethylene to the SIP panels. The layer of OSB on the inside acts as both the vapour barrier and it forms the major component of the air barrier system. Because OSB has a vapour permeance of less than 60 ng / Pa*s*m2, it constitues a vapour barrier. It’s also a nice feature to have an air barrier that is ridgid.