No one will study the strength of insulation foam because it will never be authorised as a structural material.
> Everything I've read indicates that any offgassing/odor is gone in 24 hours or less.
Everything you read comes from manufacturers or bloggers/influencers paid by manufacturers. On construction forums you'll find plenty of people complaining of weird smells months/years down the line.
Again, people do whatever they want with their houses and health, personally I'm not touching this shit with a ten foot pole given the alternatives
https://www.greenbuildingadvisor.com/question/fumes-from-clo...
https://www.sprayfoammagazine.com/forum/topic/spray-foam-odo...
https://www.reddit.com/r/Insulation/comments/1bsm8db/faint_s...
https://www.reddit.com/r/HomeImprovement/comments/bfhpmt/ope...
Definitely a risk with any type of improperly installed moisture barrier (like ZIP sheathing).
> Structural strength: yeahhhh... no
It would take me some time to find more formal studies, but there are a lot of videos on YouTube that demonstrate the addeded strength. Here's one: https://www.youtube.com/watch?v=4mMHJpSHKJM
> god awful nasty smell for days/weeks and can offgas for years is good for air quality ?
Everything I've read indicates that any offgassing/odor is gone in 24 hours or less.
> In the end of the day people do whatever they want
Agreed. To each their own. Closed cell spray foam also works well in conjunction with rockwool.