Insulating with two sidings
I am in norther NJ, Climate 4. I have a home that was built in 1900s.
It has no sill plates in the foundation and no sub floor. I don’t think it’s balloon framing because there is wooden flooring on the first and second floors in the stud cavities.
It has plaster and lath wall and small wooden beams then drywall attached on them. On the outside, there is stud, some sort of paper, plank sheathing, granulated asphalt siding and then a thin plywood and then aluminium siding.
There’s no insulation material. I wanted to insulate with blown in cellulose but wasn’t sure if I should. I don’t want any condensation issues or water pooling. Also, what are the current R value or is it even worth insulating.
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If I'm understanding your description, many walls similar to yours are insulated with dense packed cellulose which helps with thermal and air movement through the assembly. What your wall has that most don't is granulated asphalt siding, which may give you a wrong-side vapor barrier, or at least restrict winter outward drying. Considering your unique wall, I'd recommend having a local professional take a look and advise on the best path.
Also, a target R-value for your area is R-20. On retrofits, though, you sometimes have to take what you can get.