Spray In Insulation For Finished Walls?


Old 08-08-07, 07:16 AM
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Join Date: Jul 2006
Location: USA
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Spray In Insulation For Finished Walls?

I have a home built in the 50's. There is no insulation between the interior walls, and the outside brick. I was wondering if there is a product that could be applied to the space between the framing studs without removing the drywall?

I was thinking that there might be some type of foam that could be applied through a tip that is 3/8-1/2" in diameter through holes drilled into the drywall between the studs. Then after the process, I could patch all of the holes.

If I drilled the holes up close to the ceiling, I could easily cover them all with crown molding when I was done to cut down on sanding, re-painting, and texturing to match the existing walls..

Is something like this possible? Is it worth the extra effort? What about the electrical? Will the foam penetrate the junction boxes inside the walls for light switches, and electrical outlets? Any other suggestions for finding a way to better insulate this house?

I have already added all of the foam gaskets behind all light switches, and electrical outlets. I even went so far as to use caulk to seal up all of the gaps between the boxes and the drywall where they come through. I have sealed up all of the baseboard against the floors and the walls to keep drafts from coming down inside the walls and then getting into the rooms through these gaps. Literally, I have gone through each room, and made it as air-tight as possible! I use on average 5-7 tubes of caulk on each room! I actually use caulk to seal INSIDE the junction boxes where the wiring comes into them, and then caulk all of the other non-used holes to seal them as well. This house used to have pocket doors that were very poorly sealed back inside the walls. I have removed all pocket doors from the house, and completely re-framed, drywalled, and sealed everything up. What else should I be doing to see the greatest improvement in energy savings? I changed out the master bathroom window for a double paned, internally insulated window. I have sealed up every nook & cranny externally on the house to prevent bug penetration.. Can't do much about the ridge vent though as I understand the heat MUST have a way out.

What about a de-humidifyer? I have heard that they will work wonders for helping the A/C unit work better.. Any truth to that rumor?
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Old 08-08-07, 08:29 AM
czizzi's Avatar
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Join Date: Jul 2007
Location: USA
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Tell us about how much insulation you have in your attic? This is a number 1 area to look at when trying to make your house more energy efficient.

Expanding foam is sometimes difficult to control. If you spray too much into a cavity. It will literally push the drywall off the studs. I have heard of blowing in loose insulation using a similar approach to how you describe, but I do not have any experience doing this myself.

My gut tells me that by the time you pay someone to apply this, you probably could have removed the drywall, put in batt insulation and rehung the drywall and still come out ahead. Sounds like you will have to patch, repair and completely repaint anyway.
Old 08-08-07, 10:05 AM
wgc is offline
Join Date: Dec 2005
Location: New England
Posts: 362
Do not caulk inside junction boxes

Originally Posted by Go69 View Post
I actually use caulk to seal INSIDE the junction boxes where the wiring comes into them, and then caulk all of the other non-used holes to seal them as well.
Yikes, don't do that to a junction box. You can search the electrical forum for previous threads on this or ask one of those experts about this idea.
Old 08-08-07, 07:15 PM
Join Date: Mar 2007
Location: New Hampshire
Posts: 450
How about cellulose insulation? It can be blown in and it shouldn't push out any of your drywall. When its pressure packed(like it should be a in a wall), it won't settle.

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