Inside the walls

Here are two views of the wall section Tim made for me.

Working our way from the outside in, in the top photo the black strip at the bottom is Coravent, which allows ventilation behind the siding while preventing bugs from entering. The wood strips are for attaching HardieBoard siding. Then comes 3" of Roxul ComfortBoard IS, a mineral wool insulation that does not absorb water and is not affected by it. Under the Roxul is Vaproshield weathershield, affectionately referred to as "frog wrap", which is vapor permeable to allow the wall to dry if it gets wet. Then comes a half inch of Bildrite sheathing, which is also vapor permeable.

The 2x6 exterior stud wall (bearing wall) is filled with dense-packed cellulose held in by netting. The next layer, half-inch OSB (oriented strand board), is our air barrier. All wall penetrations through it (and there are only a few) are completely sealed with spray foam. The 2 x 4 interior stud wall is the chase for wiring, plumbing, and HVAC ductwork. To be accurate, we probably should have run some wires and pipes up through our sample section to make it more representative of what else is in that layer of wall. In reality it is currently open, but will be filled next week with more dense-packed cellulose, again held in by netting, as shown here.

The final layers will be drywall and low or no VOC paint. The nominal R-value of the wall, excluding deductions for studs on 24" centers, headers, and sill plates, is 49.