My attic is insulated with wool. Not having any idea just how good that performs I had a mind to augment it with the pink stuff. But I'm wondering if I can just roll it on top of the wool, or should I remove the wool first. If I do, removing it will be a job I'd just as soon not do - I'd rather pay higher bills than do something like that. The other issue for me is that they covered up all the wires with the wool, so I don't have a clue where they are and that makes my job of re-wiring just a bit more difficult - as normally I would just clip the old stuff and run the new Romex through the hole left by the bad stuff as it dropped into the wall. But that adds a different question - in the attic, is wiring exposed/insulation cut around it like is done in a wall, or does the insulation cover it?
Insulation on top of wool insulation
Jul 27, 2007
9 Replies
eigen,
I can't think of any reason not to just roll out the fiberglass over the "wool". Try to get fiberglass without a vapor barrier since the wool should be lying on a vapor barrier already.
Dave M.
just have cellulose blown on top. forget fiberglass.
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Well unfortunately there isn't a vapor barrier under the wool, just the sheetrock.
Does wool even provide decent R values or what. I've heard rumors that it works relatively well - we're talking 4 to 5 inches of the stuff in the attic.
EV-
Your blow-in rock wool is about comparable to fiberglass roll (per inch basis)
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you've got about R12 to R15
what is recommended for your area?
Even SoCal attics now get R30......Twenty five years ago I did R30 & I thought it was overkill, now its city code.
JMHO blow-in is easy & cheap compared to fiberglass batts or rolls BUT if you ever have to work in the atttic.......blow-in sucks
Blow-in cellulose is comparable to blown rock wool & fiber glass batts; fiberglass blown is lower
cheers Bob
except if the ceiling 'rock is 1/2", then fiberglass may be the better option because it weighs less and is less likely to crack the 'rock. Yeah, fiberglass isn't as good an insulation as cellulose, but the ceiling weight issue is definitely something to consider.
Well I hadn't even considered what my area wants for an R value - in Seattle is a little under R-40, probably overkill given the mild winters, but that's what it said.
the stuff don't weigh any significant amount more.
I just covered the blown-in insulation with unfaced fiberglas batts. The batts are nice when you need to work up there, for wiring, etc, because you can move them aside easily and then replace them.
Do not insulate knob and tube wiring, if that's what you have. I replaced all that in my attic before insulating. It could be wirth investigating your wiring before adding insulation.
Bob
That was the situation in my house too. The first owner put in the fiberglass. I assume that since there is both.
That's a lot more than I hda, but that in no way answers your question.
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