Insulating old house.
House has no insulation in the walls. Built about 1945. Plaster interior. A gypsum type board with concrete rough coat and finish plaster about 1/8" thick. Stud finders do not work especially well on this type wall. I have not yet contacted any insulation contractors. Last time I was around such a company, one of the workers was staggering intoxicated.
The exterior is concrete/"asbestos" shingles over plank sheathing. One of my ideas is to remove a horizontal row of the exterior shingles around the house about the top of the stud walls, drill the sheathing, blow in the insulation and reinstall the shingles. Would have to do the same under the windows. I do have some spares for the shingles, purchased new about 20 years ago.
A house in the neighborhood has plastic plugs in the same type shingles. I assume that insulation installers drilled the shingles and the sheathing, then plugged the shingle after the insulation. Looks crappy plus there is no way to know if one is drilling into a wall cavity or directly into a stud.
I have no experience with doing old work wall insulation. And I have limited confidence in the ability of the typical worker for the companies who do this work.
Suggestions for my situation?