| Couple of answers to your questions. The unisulated wall on the garage; Yes it should be insulated.Any wall that is an wall that seperates a conditioned space from a non-conditioned space needs insulation. The garage is not heated or cooled so insulate the wall. I would have cellulose blown into the stud cavities. If done properly and packed densly enough it should not settle. I would blow cellulose into the attic. Look online for insulation recomendations. Just so happens the goverment has a nice page with recomendations. (see link below) Have cellulose blown in to the recomended depth.
The insulation will last practicaly forever. The only problem with cellulose it will settle in the attic and not the walls after 10-20 years and you will need more blown in. you do not have to remove the old stuff. just add more to the level needed. The reason it settles in the attic it is not packed in densly it is just blown over the surface. the walls it is blown in and densely packed. Before you have insulation blown into the attic go up and seal all penetrations into the attic with spray foam. All the insulation in the world won't help if you don't first plug up the air leaks. |
Here is a link that might be useful: insulation recomendations
