Insulate behind outlets after the fact

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Old 05-31-17, 02:03 PM
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Insulate behind outlets after the fact

I know that new constructions homes are having insulation added behind outlets to prevent drafts through the outlets. However, how would I add insulation behind outlets in old work. I've installed the foam draft stoppers but the draft still comes through the outlets. How difficult would it be to add insulation behind the outlet boxes. My house was built in the '80s and has some fiberglass but not enough. I just don't want to have to rip out drywall and such.
 
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Old 05-31-17, 02:22 PM
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The drafts are not coming from within the wall....it is coming from the outside. Evaluate that part of your house. Does it have house wrap? Are your windows and doors insulated with foam around their perimeters. You can remove the trim molding to find out. I don't know how you would plan on insulating behind receptacles without removing the sheetrock.
 
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Old 05-31-17, 02:37 PM
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I know that the around the windows and doors there is foam. We had that done when we replaced the doors and windows several years ago. As for house wrap, I'm unsure and I will have to check on that. Would it be possible to use shoot some minimal expanding foam behind the box through the gap that's between the box and drywall?
 
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Old 05-31-17, 02:46 PM
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I doubt you could accurately deliver foam behind the boxes. Maybe. There isn't supposed to be but 1/8" around any box and the sheetrock. I don't understand why the foam cover plate seals don't work. Are you using the plastic plugs, too? They help a lot.
 
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Old 05-31-17, 04:35 PM
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And you can caulk the crack between the sheetrock and the box; that helps a little.
 
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Old 05-31-17, 05:51 PM
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One everything is together, fiberglass, box, and drywall, it's difficult to get much better than the foam covers. I tested using contact paper cut to cover the box opening plus a half inch or so and cut to fit over the switch or receptacle and it seemed a little better. I also drilled some 1/4" holes and shot in some great stuff (not the minimal expanding) to see if I could fill from behind. Risk is the foam gets into the box, not convenient. But the fiberglass didn't allow the foam fo fill completely and even a small opening feeds the air right through.

The good news is, the remaining leakage is only a tiny part of the total house leakage. If you go after all of the other leaks successfully you may actually need the extra air. There are guidelines for how tight is just right and how tight is too tight.

What other air sealing have you done or plan to do?

Bud
 
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Old 05-31-17, 08:45 PM
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The foam covers did help with drafts around the plate but the drafts go through the outlets. As for the outlet plugs, we got rid of those years ago. As for caulking the crack between the drywall, the foam covers take care of that. The only air sealing I've done to the house is put the foam covers on most of the outlets and light switches that are on an exterior wall (I ran out of outlet covers; I need to get more).
 
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Old 06-01-17, 02:55 AM
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If the air still comes through the holes in the receptacles, why would you throw away the only device that would keep that from happening? What is your siding made up of? Vinyl, wood, metal? Do you know if there is OSB under it or not?
 
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Old 06-01-17, 04:36 AM
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The only reason I advise sealing the electrical outlets (boxes) is because it is easy and the drafts are annoying. But there are bigger fish to catch with your air sealing efforts, Link below.

A well air sealed home will require all of its inside air to be replaced every 3 hours, whether that is through leaks of with a ventilation fan installed for that purpose. Additional sealing after the home reaches this level only helps to control where the air enters and exits improving air quality and protecting the home from unwanted moisture.

If your objective is to save energy the link provided will help you do that. The really tight homes are only achieved when sealed during construction.

https://www.energystar.gov/ia/partne...ide_062507.pdf

Bud
 
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Old 06-01-17, 05:59 AM
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If you used the foam inserts that install behind the plates any remaining amount of air infiltration would be so minimal that it's not worth chasing.

I'd move on to something else that would reap greater benefits.
 
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Old 06-01-17, 06:25 AM
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Drafts

Do you have fire stop installed where the electrical cables pass through the floor plates and top plates? Air can pass from below the floor or from the attic into the wall cavities if fire stop is not used.
 
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Old 06-01-17, 12:42 PM
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I don't believe that there is fire stop installed. It probably should have been done. :\
 
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Old 06-01-17, 04:18 PM
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Built in the 80's there is a high probability that you do have fire stops top and Bottom. It would be very rare for a house of that age to not have them.

Do you have a basement and is it unfinished?

Bud
 
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Old 06-01-17, 08:21 PM
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Yes! Our basement is unfinished.
 
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Old 06-02-17, 06:50 AM
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With an unfinished basement you can easily inspect all of the penetrations up into the house walls or plumbing areas and also access the perimeter rim to seal house to foundation and all seams. A days efforts down there will yield 100X the results of further receptacle efforts.

Use fire rated caulking, fire rated can foam, and some sheet metal for larger openings.
Then the same thing in the attic where you can dig down to to the work.

Bud
 
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Old 06-02-17, 08:54 AM
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I'll pick up some fire caulking next time I make it to Lowes.
 
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