Short version: if my sidewall sheathing varies in thickness by 5/32", is that a problem for applying cedar shingles, or can I shingle right over that difference? I'll be using shingles with an exposure of 4.25" and a butt thickness of 0.45".
Long version: my house currently has 7/8" plank sheathing and cedar shingle siding. The shingles needs replacing, and since I'm in earthquake country, I'm going to resheath most of the house with 1/2" Struct 1 CDX plywood. I also plan to use a 1/4" thick rainscreen mesh (Home Slicker) on top of the new sheathing.
Now there are places where I'd prefer to leave the old sheathing, like around windows and doors so I can leave the trim in place. The new buildup will be 15/32" + 1/4" = 23/32" thick, or 5/32" less than the old sheathing.
If that difference is too great, I could either use 5/8" CDX (20-40% more expensive), or use horizontal furring strips (a hassle). Any other ideas? It's too thin for 1/4" foam board.