Another milestone that I never thought would happen is all but done–the preparations for insulation. This involves netting and strapping all of our exterior walls and ceilings as well as any interior walls we want to sound/fire proof. This process has taken about a week and a half and we will begin blowing insulation tomorrow.
One of the more complicated aspects of this job is the exterior ceiling. Before we were able to begin we needed to work with our local building inspectors who didn’t think that using Typar in the roof was allowed by code. Eventually, we got an engineer to provide us with a stamped diagram of the assembly. The assembly itself is fairly complicated to execute because we wanted to create a solid air-vapor barrier below the cellulose and we are using two different ceiling materials. In the master bedroom and hallway we are using tongue and groove knotty pine, while the third floor, the bathroom, and the closet will be sheet-rocked. The vapor-air barrier behind the pine will be a cross-laced polyethylene plastic called Tu-Tuf (a superior plastic available through EFI.org); the sheet rock will be the air barrier elsewhere and it will be treated with a vapor barrier primer. Making sure that the air-vapor barrier is continuous across the top plates of the partition walls is the challenging part. This involves using acoustical sealant behind the Tu-Tuf, sheet-rock, and strapping so they all seal to the top plates. The acoustical sealant is desirable because it never hardens. So when one installs the sheetrock it can just compress the sealant that may have been applied the day before.