|geo in MI ||
Posted 02-01-2002 at 16:22:00
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I would think that knocking off the plaster will force lots of plaster chunks down inside the walls, anyway(in fact, I know it does, because a good part of the plaster actually was squeezed in between, and thus behind the lath boards), and maybe ruin most of the effectiveness of the old insulation. In that situation, I would go ahead and go all the way and remove all the dirt, debris, and insulation--then start fresh. You'll be able to see the condition of the outside sheathing, check out for any wet spots--which would have nullified the insulating qualities of the old insulation, be able to put caulking around the windows and sills, and eventually stop a lot of outside air entrance--which is just as important as good insulation. One other thing, if you are in an upstairs area in an old house of fifty years vintage, you'll probably notice that the "balloon" construction leaves the space between the floors open, since the studding goes all the way up and through the second story. That opening is a perfect place to create a fire trap condition and you should, by all means, install fire blocking--that's code on all remodels here in Michigan.
Another thing you may encounter as you tear off the lath is that the drywall thickness will be less than the original wall--you may have to do something to match the trim boards. I would suggest you save a lot of lath boards and tack them onto the studs so the drywall will match out to the original trim.
Another thing: If you have full four inch studs, plus lath tacked on, you will have plenty of room for regular friction fit, 31/2 inch X 16, or 23 inch batting--but get R-13, instead of R-11. Some places carry only R-11, which is a tad cheaper, but not in the long run Even though it's itchier(well, only a little bit). the friction fit, instead of kraft paper faced, will allow you to stretch and tease it into place to make sure you have all the airflow stopped.
And still another thing, by removing the old insulation, you will probably want to use batting instead of blowing cellulose, that way you can insulate beneath the windows, too.
Hope this helps.