New construction exterior sheathing

10-4 on the mold situation. This is why I’m trying to ensure vapor, water, air barrier/permeability is addressed appropriately on the front end. I’ll be vetting the spray foam sub. I do plan to go with builder recs (within reason) for underlayment as long as they have good experience with foamed/tighter envelopes.

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henry blueskin

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This seems to be very ideal as a water/air barrier that is still vapor permeable allowing moisture to dry from the inside out. Wasn’t sure if many builders are using anything like that in South LA.

Look for the tyvek spec. Or call them. They’ll work with you if you use their product. Osb is fine on the wall. I don’t like osb on the roof. We use 98% 5/8 cdx on roof deck. Rarely get a request for osb.

Zip system. I will never build another structure without it, until something better comes along. The "stretch tape" alone is worth using it.

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With Zip panels, do y’all flash wall penetrations with the tape or the liquid flash? I’m guessing both liquid and tape might each be better in some applications than the other. If Zip is used for roof decking, would you still top it with IW shield in the valleys, hips, sealed ridges, eves, etc. or just shingle strait on the zip in those areas?

I would ice/water the valleys. Google FORTIFIED roof system. If I were building new, I would make sure the roof meets the FORTIFIED standards and the contractor can provide proper certs stating the roof complies. Reason being a)it is a well studied process for a more wind resistant roof b)most insurers will offer a discount on your home insurance.

If I could start my career over again I'd be a building science geek. Building durable structures is satisfying, and desperately needed.

Can't say I've ever seen or heard of it done like that. First impression is thats a lot going on with a wall assembly. Its not easy to find a builder (if you're going to use one) who is willing to do unknown things. They like doing things they are used to with no learning-on-the-job surprises. Poorly installed zip or wrap is going to suck no matter what. Also, with the cdx sandwiched between wrap and foam, I'm not sure there is enough ability to dry if water gets between them. Tyvek has decent permeability but a few inches deep open cell is very little perm. That plywood may be wet for a long time before drying. I just don't know.

My personal favorite wall assembly accounting for cost and performance is: generous roof overhangs then cladding~rainscreen~zip (or zip-R)~rockwool insulation. But there are many ways to skin that cat and new products are being put out every day.

Seems like you're thinking things through and want a well built home. I'd suggest spending a little money and time on greenbuildingadvisor. Not sure how familiar you are with it but they are more building science oriented than "green" which is a bit misleading. Once you've formulated a thoughtful idea of what you want, you can ask questions and get good answers possibly even from authors and industry experts who love talking building science. Just be mindful to ask good specific questions. Not, "so whats a good way to insulate a home" . Ain't nobody got time for that shite. Caveat; I haven't spent much time on there in 5 years so I think that's still how it works.