Attic Insulation - what's best?

pacific_flightsJuly 10, 2013

I'm sure this has been asked and answered, so please forgive me for asking again, but I've read through some threads and I am still confused.

I'm having my 1930 house re-roofed next week and thought it would be a good time to do the blown in insulation (while some or all of the roof is off). I currently have about 4 inches of something that looks like loose cellulose. Another section of the house has what looks like vermiculite. I had planned to add about 10 more inches of blown in cellulose (I live in Northern Nevada near the Sierras, so we get snow in the winter and summers can reach 100 deg.)
When I called HD this morning to inquire about renting the machine, the guy told me that blown in fiberglass is much better, and that he wasn't even sure whether they still had the machine to do the cellulose. Does this sound right? It caught me by surprised because I thought the cellulose was the way to go. For some reason I'm not too keen on the idea of doing fiberglass. What do you guys think?
Thanks! Jenny

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There were "concerns" about the insect-proofing used on cellulose. Nothing actually proven, but the OMGTOXINS!! crowd started a big uproar about all the possible chemicals and potential carcinogens on the recycled newsprint (it's 50%+ post-consumer content) and many retailers decided to stop carrying it. Fiberglass requires no fireproofing and has no printing ink.

Before you start blowing insulation:

Are you planning any ductwork, wiring and can lights? If so, postpone the insulation until they are done and inspected. The insulation blower and raker should be the last person in the attic.

Make sure you have the baffles (the nail to the rafters) so you can pile insulation along the outside walls without blocking air flow up through the soffit vents. (if you have them)

Blowing fiberglass (it's in small chunks) is a PITA, but with a painter's disposable paper overall, a hood and a mask it's not hazardous. Do it in early morning, and shimmy out of the overall so it turns inside out with the fiberglass on the inside. Then take a shower and wash your hair.

    Bookmark   July 11, 2013 at 9:35AM
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If I had the chance I would insulate the rafters and seal the attic.

    Bookmark   July 11, 2013 at 9:40AM
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Not planning any ductwork, can lights, or wiring. I don't have soffit vents, but the roofer is going to put some in for me. The current insulation is packed all the way to the edges so I'll have to move it out of the way and install the baffles. Still thinking I'll try to use the cellulose if it's an option...fiberglass sounds miserable! :)

    Bookmark   July 11, 2013 at 4:38PM
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Cellulose is just as miserable to install. it's dustier and just as itchy.

    Bookmark   July 11, 2013 at 10:33PM
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Circus Peanut

I DIY'ed the cellulose and have one recommendation: don't rent the machine from the big box store. Go to a real tool rental place -- the difference is rather marked. In our case, the one from Lowes did not have the remote stop on the blower, which we quickly discovered is pretty vital when you're on the job. You do need an on-site helper who can shout to you to stop when they need to fill up the hopper, etc. We didn't find the cellulose to be itchy, just very dusty. Wear the appropriate masks, clothing, etc, and prepare for a lot of vacuum clean-up afterwards.

Another good tip someone gave me is to get a large sponge and slit a hole in it -- poke the end of the blower pipe through it and you can eliminate a lot of blowback. (This applies to doing walls with 4" blowholes; may or may not apply to attic filling.)

Good luck! We did our walls and enjoyed a major improvement in furnace efficiency and sound insulation.

    Bookmark   July 12, 2013 at 11:16AM
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I have to say...I hate cellulose.
the fine 'dust' finds its way into the house via
every small gap/crack/hole.

the few clients of mine who have cellulose complain
of 'dust' which is actuall small pieces of newspaper
treated with borate, and allergies..the latter from
breathing in borate treated particles.
once we air seal between attic & living space
below...insulation stays in attic rather than
circulating through the house.

leaky supply boxes & returns are great for sucking
particles into the house/system.

I put batts in my attic. one layer in joist bay
second unfaced layer run the opposite way to cover
all faces of ceiling joists. if I ever need to do any
work like is easy to move insulation.

prior to any type of insulation...air seal.
else air leakage filters through insulation
prior to entering the house.

best of luck.

    Bookmark   July 12, 2013 at 5:32PM
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Circus Peanut

leaky supply boxes & returns are great for sucking
particles into the house/system.

Ahh, I hadn't considered regional differences. Up here in Maine, there is nothing in the attic but last year's Christmas ornaments and Junior's broken sled. We put our ducting in the basement, where it belongs. ;-)

    Bookmark   July 14, 2013 at 9:52PM
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what you going to do when you live in an area
with a high water table??

most folks opt to put equipment & ducts in attic..
or if the house is raised on the crawlspace.
some of us put ours inside the living me..
but design of house determines if this is doable.

    Bookmark   July 15, 2013 at 7:46AM
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Thanks for the tips circuspeanut. I'll call the local tool rental place today.

Also, my ductwork is in the basement, so dust in the house shouldn't be a concern.

    Bookmark   July 15, 2013 at 12:05PM
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