Rim joist insulation

Out2pasteur

I have a decision to make about insulating the basement in my 1958 ranch and was hoping to get some feedback.
The basement is about 1/3 finished. There is no insulation anywhere. Just slab for 2/3, and in the finished part is only flashing behind the drywall. No foam or batts. The basement is dry, with a sump that has only kicked on 2-3 times over 3 years (putting in a back-up anyway)

Ive read the first thing to do is to air seal and insulate the rim joist. Easy, but there is an obstacle. All of the ceiling down there is plaster on metal lath--even in the finished part. There is really no way to access it without ripping i the ceiling all out.I did remove one portion ~ 20% in the unfinished part and there were plenty of gaps and drafts that I sealed, and covered with 2 inch foam.

Will the benefits of doing the rest of the basement be worth the effort?

The current ceiling is ugly, but this becomes a big project quickly if I commit.
I'm in Massachusetts, and the basement (and hardwood upstairs) gets pretty cold in the winter.

bubbler

I have the same thing in about 1/4 of my basement... that stuff is a nightmare to remove.

I wonder if there is any way to drill 1-2" holes near the joist and use a spray foam? Sort of like you'd do with your siding off to do so blown in insulation.

Out2pasteur

Thanks for the reply,
You're right about getting that stuff out. It's heavy and will cut you to shreds given the chance.

My concern about cutting holes is that
1) ripping it out is almost easier than cutting a hole in it.
2) patching it so it looks good is also probably a challenge

Although, I may give it a try in a dark corner somewhere, and see how it works.