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Attic Insulation: Batt vs. Loose Fill

luddite20's picture

Attic Insulation: Batt vs. Loose Fill (post #205566)

luddite20 on Mon, 01/02/2012 - 10:37
in

Hi Everyone-

I'm about to install insulation in our Bay area CA home.   Our home is old, and has knob and tube wiring, which I will update prior to insulation.  My question is this, given that I'll probably want access to the attic from time to time to update new circuits and potentially add on to our house or add skylights, should I use Batt insulation?  Everything I've read and everyone I've talked to speaks to the potential to poorly install batt insulation, and that loose fill is much more effective.  This makes sense, but if I plan on adding circuits or accessing this space a few times a year, wouldn't batt, properly installed, make more sense?

Thoughts?  Declarations?  Rants?

 

Chad

-A +A

Proper installation would be (post #205566, reply #1 of 4)

by Hammer1 in reply to luddite20 [original] on Mon, 01/02/2012 - 11:24

Proper installation would be the key to either. Fiberglass itself doesn't insulate, it's the air that is trapped in it that does the work. If there are any gaps or compression, the insulation value is compromised. Here in Maine, batts are the choice in new construction. If an older home has uneven or oddly spaced joists, that can make for a lot of extra work and any slight misfit will lower the insulating value. You want the batts to fill the cavity and be able to expand completely. R38 is the minimum here and that means 12", usually double batts installed perpendicular to each other. Adding a third layer starts to add weight which can compress the first layers. When higher R values are wanted, either or both layers can be thicker than the standard 6" or blown is used on top of a double layer of batts.

Loose blown was used around here on top of batts for a short time during the 90's. It quickly fell out of favor. Completely blown loose isn't something I've seen or lived with. Someone else would have to address whether it gives the same values batts do. If I were doing my own place, I'd choose the new, white, no itch, formaldehyde free batts. If they fit your situation they would be easier to remove and replace when needed and still maintain consistent loft and density.

Beat it to fit / Paint it to match

Install blown cellulose.  If (post #205566, reply #2 of 4)

by DanH in reply to luddite20 [original] on Mon, 01/02/2012 - 12:58

Install blown cellulose.  If you need to install some wiring, just get yourself a child's snow shovel (granted, maybe hard to find in the Bay Area) and dig out the space you need to access.  You may want to wear a dust mask, but the stuff is not itchy to work with and digging through it is not difficult -- much easier than wrestling with batts.

Just be sure to build up a decent height barrier (set back about a foot) around your access holes, so that the stuff doesn't come tumbling out every time you go up there.


We are like tenant farmers chopping down the fence around our house for fuel when we should be using Nature's inexhaustible sources of energy -- sun, wind and tide. ... I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait until oil and coal run out before we tackle that. --Thomas Edison

Agreed (post #205566, reply #3 of 4)

by davidmeiland in reply to DanH [original] on Mon, 01/02/2012 - 14:33

Install cellulose, move it out of the way when you need to add stuff in the attic.

Loose fill always provides (post #205566, reply #4 of 4)

by Clewless1 in reply to luddite20 [original] on Fri, 01/06/2012 - 07:50

Loose fill always provides better coverage to fill odd areas and such ... leaving no voids. Batts simply cannot do that well unless the install is meticulous ... which it will not likely be.

Worst case for loose fill ... get a blower and reverse it and suck out what you need to do work.

I've heard some talk about nob and tube wiring and code issues w/ insulation in contact with it. ... Don't know if there is anything to that. I've done my own old house w/ cellulose and seen others done (doesn't mean it met code, though). A quick call to the BO would answer that question, maybe.

There ain't NO free lunch. Not no how, not no where!