Insulating finished wall-foam or blow in?

[sosnpk]

I am taking on the task of insulating our 1946 house. I am in the process of removing the wallpaper in the dining room and figured since I am going to be filling in holes to prepare the wall I might as well look into insulation. The room has one exterior wall, 2 interior and one facing the unheated garage. Should all walls be insulated? What is the recommended type of insulation for behind these plaster walls, foam or blow in insulation? Any tips for install?

[HayZee518]

foamed insulation makes the tightest barrier on exterior walls because it's sprayed on. If your walls are bare inside then foamed is the way to go but its expensive. what you want to do is prevent or lessen the migration of outside to inside air.
If you want to insulate without removing the sheetrock or if its a plaster wall over metal lath bore 2" holes in the 2X4 wallspace and blow in cellulose insulation. It's fireproof and has an R rating of about 9 or 12.
Then patch up the holes and go forward with your project. I have never seen insulation on inside walls, but its good for sound proofing.

[kactuskid]

insulating walls

Insulating the exterior wall and the garage wall would benefit you in saving energy. As Hazy mentioned, blowing in cellulose insulation is one of the ways to do it. I would hire a pro though since in older homes there were usually boards placed across the stud cavities mid wall, these were used as fireblocking. So insulation would need to be blown in above and beneath these boards so the entire cavity is filled.

You'll also want to paint the walls with a vapor barrier primer/paint after insulating to prevent moisture from entering the walls from the interior. BIN made by Zinsser is one of these primers.

Below are a couple of articles that'll fill you in with lots more details.

http://www.oldhouseweb.com/stories/Detailed/10215.shtml

http://www.healthgoods.com/Education...insulation.htm

[LazyPup]

Hayzee,,,I have a question in regard to older homes circa 1945 or older. Many of those homes have some knob & tube wiring. Would it be advisable to add insulation in wall cavities with K&T wiring??

[kactuskid]

That's a good point to bring up LazyPup, if there's K&T wiring in the walls, then you don't want to pack insulation around these wires. That's something that would need to be verified prior to insulating.