New insulation installed over existing - vapor barrier question

[delphiprog]

Hi and thanks for your help.

I live in Ohio, and this past weekend I installed fiberglass insulation over top of some (about 2-3 inches) of blown in insulation. The mistake I made was not removing the paper backing vapor barrier. Well, actually the first mistake I made was not reading about how to do it prior to actually doing it; but that's another issue. Anyway, damage done. My question: is it sufficient to simply go back and cut some holes in the back of the strips (each strip was 24" X 48") of insulation, or do I need to completely remove the paper backing?

Thanks Doug

[No]

Which way is the paper facing? Either way I would probably say just go have a beer and get on with your life. No worries.

[delphiprog]

It's facing down. It would take some time to correct, but that time is worth it now if it's going to cause moisture buildup in my attic in the future. Sounds like you don't think it really matters much. It certainly isn't an air tight seal so I guess it may be OK...

[Bob]

Persanally, I'd remove it. The potential for damage is too high. Expecially if the previous insulation has no vapor barrier. Slashing it repeatedly might do the job, but is probably as much work as removing the barrier. The risk is condensation getting the old insulation wet, rotting the wood beneath or causing ceiling problems or mold.

Bob

[delphiprog]

There is no existing barrier. If there was I'd probably not worry about it as much. Thanks for the advice.

[Stormin Mormon]

The vapor barrier should be on the heated side. I doubt the paper foil will remove very easily. So, if the foil is on the heated side, it should be OK. If the foil is on the cold side, then the insulation can get cold, and condense the moisture from the indoor air.

[Bob]

If the vapor barrier will have insulation below it, I would strongly disagree.

I sharp thin bladed long knife will quickly strip the barrier off. I would use an old butcher knife and hit it with a steel frequently.

Bob

[Carl]

an old butcher knife and hit it with a

I don't see the original post. there is an exception to the rule . "So, if the foil is on the heated side, it should be OK." In a basement, where the walls are cool but not freezing, I recommend vapor barrier on the cool side.

Basement walls weep moisture. You can have a mildew and mold buildup in the wall if the basement is finished and IF THE VAPOR BARRIER IS ON THE WARMSIDE.

That wall has to breath... it can't if the vapor barrier is on the warmside of the insulation to the concrete wall.

[Bob]

use an old butcher knife and hit it with a steel frequently.

O.P. wanted to add insulation over old insulation in the attic.

Bob

[delphiprog]

It's actually not foil backing; it appears to be some sort of paper/plastic type deal. I have already completed part of the job by simply pulling the paper off. It seems to separate quite easily, although not always without a small bit of insulation coming with it. A negligible amount really. I have not encountered any condensation yet, but it hasn't gotten extremely cold either.

Again, thanks for all the responses.