Any Tricks for Repuffing Old Fiberglass Insulation?


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Old 11-05-20, 03:57 PM
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Any Tricks for Repuffing Old Fiberglass Insulation?

Picked up 48 rolls of R-25 from Menards last night to put on top of the R-19 already laid in the 2x6 joists of an attic. Had already paid for it (got a really good deal) and was just getting what was on my pickup ticket. Was very annoyed to find all of their stock was 1.5-2.5 years old. Normally, I would have passed it up, but it was already paid for and I needed it soon.

Got it home and found exactly what I was concerned about: the compressed rolls don't come out anywhere near their intended thickness. Package says 8.5" thick, and they roll out maybe 2-3" thick. Wouldn't even fill a 2x4 wall. Manually fluffing them up maybe gets to a somewhat stable 6-7" and I'm not convinced it'll stay that thick.

Does anyone have any tricks or advice here? Clever ways to get it to recover to full thickness?
I could return it, but I got it at such a great price that I would cringe at buying something else. I'd probably never earn back the cost difference on heating and cooling, and I could double-layer the R-25 much cheaper than I could buy R-30.
 
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Old 11-05-20, 04:06 PM
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All the insulation comes off the factory floor rolled up and sealed or wrapped in a sleeve, compressed to save space. I'm not sure a fresh roll would be any different. We have insulation in our stock that has to be at least 5 to 6 years old next to brand new stock and they all store in the same size roll for any particular R factor. Using a glove I would just try to fluff up the worst of it and not worry about it. I doubt you could notice a fresh 8" high piece vs a 6" or even 3" high piece to be any different in insulating power.
 
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Old 11-05-20, 04:13 PM
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Its all compressed when packed, just lay it and be done.

Better option would have been cellulose, IMO, much easier to install, air seals much better but nothing wrong with what you have!
 
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Old 11-05-20, 04:26 PM
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I usually use cellulose, but won't in this attic because it already has some good fiberglass and I know I'll be up there sometime in the next couple years to do work. I'd rather roll back the fiberglass than wade through cellulose.

I've bought this same R-25 product before and it puffed much more straight out of the roll. I've had several experiences will older fiberglass (some that I've kept for years), and I'm always used to the older stock not wanting to decompress.

Pretty sure thickness is directly correlated to R value. Can't recall which manufacturer said this, but I remember reading that R-19 squished into a 3.5" wall bay will work fine, but will only have an R-13 insulation value.
 
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Old 11-05-20, 05:04 PM
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True thickness is a factor, but in the long haul as your trying use it I doubt you see any significant loos of insulation.
 
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Old 11-05-20, 09:12 PM
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Compressing it does increase the r-value a bit, I don't have the numbers. If this is being installed across the existing fiberglass (perpendicular) as a second layer it will fluff over time.

Wild thought, but exercising those rolls before you open them might encourage them to fluff.

Just be neat and avoid gaps under and between the new batts. Bounce the rolls around a little and see if it helps.

Bud
 
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Old 11-06-20, 04:57 AM
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I try to make that initial compression my advantage. If they need cutting I keep the bundles compressed until right before cutting. The thinner, compressed insulation is much easier to cut. Then the handling of picking it off the floor and putting it in place is often enough to get much of it's fluff back. But, if the insulation you got is bad or defective I would return it.
 
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Old 11-06-20, 05:53 AM
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I would send an email to the manufacturer including photos of the bagged/compressed and the unrolled bats with a yard stick showing the diminished loft. Tell them you don’t want to remove it and figure out how to return it to the retailer. Ask them what to do about it and what the reduced R value is. They might want to make it right. Or at least tell you what the reduced R value is.
 
 

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