Insulating old house while doing rehab

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  #1  
Old 09-06-09, 09:37 AM
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Insulating old house while doing rehab

I have an old house (1808) and am redoing the wiring. I've channeled a lot of walls (interior and exterior), put in holes all over the place, and found a bunch of deteriorating walls with no insulation.

The house is in Northern NH so insulation is critical. The questions are:

1. In the deteriorating walls (both interior and exterior) is it better to remove the wall and either spray on / install fiberglass insulation or is it better to leave the wall intact and put a piece of sheetrock over it for the interior wall and rigid board insulation + sheetrock on the exterior walls.

The advantage of the second option is that it's less time consuming and I don't have to pay for carting away rooms full of horsehair plaster and wood lathing. The negative of this method is having to remove, replace - and of course fix - the existing moulding.

My concern is that the building was designed to breathe. It's been around for over 200 years and the wood is just fine. Maybe trying to make it air-tight is a foolish idea? There are also many windows -- too many windows -- so going overboard on the walls do not make any sense. (The house was converted from a Federal into a Victorian in the 1880s).

I think it would be better to put "storm windows" around the porch and have a 6 foot air barrier rather than spend the same amount of money spraying icynene or airkrete in the existing house.

2. The second question is somewhat related to the first. I was planning to use spray can insulation where I cut open the walls for the new electric. However some cavities are huge, like 40 inch huge using 4x10s and odd sizes as they tended to do back then. However if the foam will not stop the air from circulating then it's only use is it's R value.

And -- I know I'm repeating myself -- is stopping the air from circulating behind the walls a good thing in an old building designed with this is mind?

Thanks all.
 
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  #2  
Old 09-06-09, 03:18 PM
Join Date: Dec 1999
Location: South Dakota
Posts: 3,140
Insulation in walls

It seems to me by reading your post, that your looking for 2 things. The cheapest way and the easiest way. To do it correctly you should tear off your inside wall board and put rolled insulation in between the studs. You can spray, but that is more expensive. To put up sheetrock with foam board is just a waste of money. The foam panels have a very low R value. You would be better to insulate then install new windows at a later date. Good Luck. A job like this is worth doing well.
 
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Old 09-06-09, 04:09 PM
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Originally Posted by Jack the Contractor View Post
It seems to me by reading your post, that your looking for 2 things. The cheapest way and the easiest way. To do it correctly you should tear off your inside wall board and put rolled insulation in between the studs. You can spray, but that is more expensive. To put up sheetrock with foam board is just a waste of money. The foam panels have a very low R value. You would be better to insulate then install new windows at a later date. Good Luck. A job like this is worth doing well.
I was just coming to the same conclusion. The walls that are falling apart I'll pull all the way down and insulate them. The others ... I think I'll leave them alone for the moment.
 
  #4  
Old 09-06-09, 07:19 PM
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Location: New England
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The idea of adding rigid insulation over sheathing or interior drywall is always an option, but it would be a shame to leave those cavities empty. Check to see if they run basement to attic as in balloon construction. If you have balloon construction, you will want to seal all passage ways to reduce air leakage and improve fire related issues. Blowing in cellulose or other insulation is another option.

Also, check your lumber yards and big boxes as new products are coming out all the time. A local lumber yard in my area just started carrying a product that looks like dense mineral wool. Europe and Canada have been using the stuff for a long time and the specifications I read looked good. Check your area.

Most importantly, while you have things torn apart, this is the best time to do all of the little things. Check out air sealing and don't worry that you will get it too tight. Learn about vapor barriers. And plan for tomorrows energy costs or last falls prices as they will be back. Here is some reading.
Welcome To Home Energy Magazine Online
Energy Savers: Vapor Barriers or Vapor Diffusion Retarders

Enjoy
Bud
 
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