I'm sure many better minds than mine have worked on this question; has anyone come up with an effective buildable wall for cedar shingle siding, that doesn't involve two layers of sheathing? It seems that I need one layer for structural integrity in my coastal wind zone (02807), and a second layer outside my exterior rigid insulation, for a nailing base. It also seems as though the inner layer should be the air barrier (Zip system?), given the thousands of shingle nails. So, unless someone has a better idea, proposed stack up would be shingles, CDX, 2" xps, taped Zip, 2x6 frame w/ cellulose, blueboard/plaster, paint. Questions: Is there a way not to use two layers of sheathing? Do I need a WRB behind the shingles, and if so, what? Would taped polyiso make an air barrier instead of Zip, or do the shingle nails preclude that?

strap the wall horizontally with 1x pine over the foam, spaced the same as the shingle exposure. This leaves an air space behind the shingles so the back can dry, extending their life.