https://www.homedepot.com/p/Owens-Corning-R13-Thermafiber-Fire-and-Sound-Guard-Plus-Mineral-Wool-Insulation-Batt-15-in-x-47-in-1310109/319880476

This is the kind of thing I would suggest, it’s designed to be soundproofing, fire retardant home insulation. This is literally the exact thing you would put in-between your joists before drywall if you were trying to insulate an interior wall for sound.

There’s a product called green fiber that is a blown-in cellulose insulation that’s been treated with fire retardant you could use if the walls have already been drywalled, I’ve used that in all of the interior walls of my home when I was remodeling to try and deaden sound and have added privacy throughout the home. My basement, which I turned into a mother-in-law apartment, is so private I can’t hear my basement neighbor when they have their video games blasting through a surround sound stereo set with a subwoofer. I can feel the floor shake but, unless I am standing right next to a vent, I can’t hear anything.

Two so far. Hoping for more. X)

It’s a fantastic series, very digestible too. The audiobooks would be super easy to finish in a weekend.

Ooooooh! That sounds awesome! The fact that it was bear proof in the books, as well as being light enough to be pulled by an e bike makes me think carbon fiber and/or aluminum. Makes me wanna do some design mockups with rough sizing and structural estimates. Not artistic enough to do any of the murals on the sides with the gods but it would be fun to try to do structural theorizing.

(Not an engineer, i just like thinking through problems like this)

Showers/tubs should have a access panel on the other side of the wall the faucet is on so you can get at the plumbing. Mine didn’t (also 1960’s house) so I cut an access hole and got one of those spring loaded wall hole covers that are designed to allow wall access without cutting every time.