2013 08 07: the picture shows the roof’s air barrier. passive houses have an air barrier on all sides, including the roof, that prevents air exchange with the outside. the black tape keeps air from passing between the sheets of oriented strand board (osb). in the case of the old hopkins road house, the roof’s air barrier is the layer shown. over this will go 2 x 10s that will form cavities for seven inches of mineral wool. under the air barrier is 16 inches of blown in high density fiberglass insulation.