Replacing 'lost' insulation within wall cavity?

pjb999February 9, 2009

Decided this is best as two posts, so I'm going to deal with just one issue here, all suggestions appreciated.

Had to fish a wire through an outside basement wall- there is a 2x4 wall inside of the concrete wall of the basement. 80's vintage so the moisture barrier etc is not up to today's standards, and I noticed behind at least one outlet, they did not bother to insulate, which I've done before replacing the outlet box (had to remove so I could drill and fish wire through stud)

In order to fish the wire, I had to cut a couple of small holes in the wall to get the drill bit and fish tape through etc. After some prolonged probing etc the insulation is now pretty munched so there's quite a gap in these areas. I had figured on poking small tufts of insulation into the hole to replace it. As I understand it, you don't want to pack it in too tight or it will lose its effectiveness by not having enough puff in the insulation, so would this method be adequate? I had also considered spraying some spray foam, the spray can type, into the gap, I figured when it expands against the drywall and the remaining moisture/air barrier against the drywall, it'll seal it up, becoming its own barrier in that spot.

Does this sound ok? I will be encapsulating the new wire I ran through there which I assume will be ok. Is the combination of fibreglass (it's r-12 stuff if that matters) and spray foam adequate, or would I be better off just using the spray foam for the gap? It'd probably be the lower expansion stuff that's supposed to be safe for doors and windows.

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You know there are gaps, but you don't know how big they are. Either solution is a guessing game.
If you want it done correctly, open the wall and insulate it properly. you'll probably find there are many more gaps then you think.

    Bookmark   February 11, 2009 at 1:43PM
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I have no doubt the wall was poorly insulated, but opening it up is not really an option for me right now. I'll just have to fix it for now. I have a fair idea of the size of the gaps, because you can see/feel them around the holes I made.

    Bookmark   February 11, 2009 at 4:07PM
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Not to be a smart ass here but I guess it's cheaper to do this a 2nd time when you have the time to do it right ? What not take the time now and tear it up and do it right and be doen with it once and for all. Cahnce are the insulation is wet or damp and there's no vapor barrier and to top it off the nisulation job was done half ass to begin with. If I were you I would tear the walls open and replace all the insulation with a good spray foam and re-drywall and never have to worry about it again.

    Bookmark   February 16, 2009 at 5:27PM
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I appreciate the sentiment and agree with you in one sense, but there would be very little point in doing just one spot and even that's not an option since I'm not working (got the time, but no money) since I might be faced with the whole house being done that way.

The particular spot where this problem is, could be a future option and when I get some spray foam done in the garage I may ask them to do this one section but in the meantime I want to just do fibreglass because I will have to remove some insulation when I replace the main water shutoff, don't want to attempt that when there's sprayfoam all around when I'll be using a torch!

Insulation is wet only in one spot where a hole was made in it and not replace, I will be cutting that part away and re-doing.

    Bookmark   February 16, 2009 at 7:06PM
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