I have an older house that has no sheathing on many parts of the house. I’m planning on re-siding this summer by taking off the old siding, adding sheathing and re-siding. Some of the walls are fiberglass insulation and some have cellulose (not really dense packed…it was done many years ago). What are the best options for adding both a wind barrier and high insulation value (I’m in zone 6). I’ve thought about rigid foam both cutting and fitting between the studs and overlaying on the sheating or both. I’ve also thought about spray foam from the outside, however some of the walls are almost 8″ thick (it’s an old post/beam construction). Cost isn’t a huge issue…I want it done right, however spray foam a wall 8″ thick is really expensive. Any thoughts?