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I have attic filled with old grey blow in insulation. I estimate it to be 20-30 years old. I suspect that it causes a lot of dust in a house. Plus any work in attic would stir it and some will end up in rooms. So should I just remove it and replace with new insulation that comes in rolls? I think it would insulate better, too.

Pros and cons?

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Why would blown in insulation cause dust? Are you up there stirring it up? –  The Evil Greebo Sep 15 '13 at 22:05
    
The attic air space should NOT be connected to your house -- if it is, you're going to have heating/cooling issues along with air quality problems, to start with. The attic space should, however, be vented from the soffits and out through roof vents to prevent moisture/mold problems and prevent ice dams from forming in the winter. –  gregmac Sep 16 '13 at 16:26

3 Answers 3

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Replacing doesn't make fiscal sense. Nothing wrong with the old insulation unless it's been disturbed and compressed. Just add NON-faced batt insulation on top of the existing.

Or you could blow in more insulation - but then you'll find out what dust is really like.

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Why removal doesn't make fiscal sense? I think I can just pack it in few bags and vacuum whatever is left. It didn't look like a lot. Although looks are often deceptive. –  Uncle Meat Sep 15 '13 at 22:30
    
Because it's already there. In order to get the R value you want, now you have to clean it out, bag it, dispose of it properly, and then replace it ON TOP of what you could just add anyway. Add more = X. Replace = X + More. –  The Evil Greebo Sep 16 '13 at 12:16

I dont like batt insulation in attics because you are left with the space above the ceiling joists that is not insulated. This is especially a problem with 2x4 trusses. With todays codes calling for 15+ inches of insulation it will be higher than any ceiling joist. I agree it doesnt make sense to remove old stuff take that time saved to seal the attic from living space. Recessed lights are often the culprit.

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I agree with removing the old instead of piling on top of it with new. You want the least compressed stuff closest to your ceiling. The opposite would be true if you were to simply through the new stuff on top of the old. That is a waste of money. Also, by simply piling on top of the old you are probably furthering a mould problem too that you wouldn't even notice.

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Why do you need the least compressed insulation closest to the ceiling? Isn't the normal course of affairs to have the upper layers compress the lower layers? –  Niall C. Feb 24 at 3:32

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