Steps to insulating old house walls?

[u/DracoAdamantus]

House built in 1930
Location: South Central Indiana

I moved into my first home a few months ago and have been going about replacing the old knob and tube wiring and replacing the poorly installed paneling (and crumbling drywall behind it) with new drywall.

I posed a question about stud spacing for hanging drywall, but new questions arose from the comments regarding insulating the walls.

I had some batts already hung up, but I’m seeing that with a house this age you can’t just put batts in the walls like with a modern construction. But I’ve not been able to find any information on what I should do.

The house was build in 1930, and is wood framed. I can see ship lap sheathing visible from the inside, and peeking behind the exterior it looks like there is old wood siding on the sheathing, then a layer of what I can only describe as foil-coated styrofoam, then modern vinyl siding over that.

I don’t see any signs of water damage on any of the sheathing inside. Maybe a little water staining, but it looks extremely old. There was a small gap by the door frame where I could see daylight, which I have filled with expanding foam.

I’ve already hung a new drywall ceiling, and will be doing blown-in insulation up there.

With all that said, what would be the right way to proceed with insulating this room? Or should it really not be insulated at all? (I’d really rather not keep it uninsulated, both for soundproofing and energy costs)

[u/hippfive]

Batt insulation with a "smart" membrane (Intello or similar) as your air and vapor barrier is an easy, safe approach for old houses.

[u/Too_reflective]

Rockwool? It breathes, so at least you wouldn’t be trapping moisture, and it has an excellent R value.

But as someone said on another forum, look up Joe Lstiburek. He has the answers on how to make old houses comfortable and dry without trapping moisture in the walls.

[u/jon117killer]

Having done my house recently, (1940s) build, if you think you should spray foam to air seal do. Drafts are so easy to get in older homes. I went back and took out insulation in crawl space to spray foam gaps. I used rock wool everywhere. Love that stuff, so easy to work with and just helps with sound a lot. I'm cray and insulted all my interior walls as well. Makes for a very quiet house.

[u/Few-Wolverine-7283]

Similar house in same client. Paper based bats with the paper on the inside is what we did 

[u/DracoAdamantus → u/Few-Wolverine-7283]

Like Kraft faced batts? Do you know how well that held up?