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m_taggart

attic insulation

m_taggart
11 years ago

We bought our house a few months ago; it was built in the 70's. The insulation in the attic is laughable. It appears to be the original insulation and average thickness is approximately 2 inches. I can see drywall in some spots. I'd like to add insulation at some point this year and am seeking advice.

First off, batts or blown in? I know I could do either myself, as the local hardware stores will provide the blower for free if enough insulation is purchased. We plan to have a new roof put on in the next 5 years or so, and I'm wondering which will pose less of a hassle when the crew installs soffit vents (we have gable vents only). Should I install soffit vent baffles while I'm up there in anticipation of having the soffit vents installed?

Second, cellulose or fiberglass (if we decide on blown in). My concern with the fiberglass is that it has been classified as a suspected carcinogen. Obviously once it is in place in the attic there is little to disturb and the risk is minimized. On the other hand, I've read that the cellulose, while treated with fire retardants, does pose a fire risk. We have aluminum wiring, which does pose an increased risk of fire. I plan to inspect all connections and fixing if there aren't done with co-al approved connectors. The other thing about cellulose is I've heard it settles more than fiberglass, thus decreasing the R value. True?

Third, I would like to have a bit of storage space up there. Is it possible to build a raised platform to provide room for the insulation underneath?

Comments (7)

  • m_taggart
    Original Author
    11 years ago

    Also, is a vapor barrier required with blown in insulation?

  • ionized_gw
    11 years ago

    The question of where you live (or what is your climate like) is very important to answering this question.

    In addition, you should probably read the recent thread about insulation in the HVAC forum.

  • m_taggart
    Original Author
    11 years ago

    I live in the piedmont of North Carolina near Raleigh.

  • energy_rater_la
    11 years ago

    as ionized posted, check out insulation thread
    in hvac forum
    air sealing & duct sealing should be done
    prior to adding insulation.
    fyi..I like batts. second choice would
    be blown fg. cellulose is never a recommendation
    except in walls due to borate/dust issues.

    as for the walkway...
    before any insulation is added
    toenail 2x6's across ceiling joists
    with screws. this will give you 5 1/2"
    more for insulation.
    when insulation is completed screw
    plywood to 2x6's. mark on plywood the
    location of any plumbing, electrical & anything
    that you may need to access in the future.
    a little foresight sure makes a difference.

    best of luck.

  • m_taggart
    Original Author
    11 years ago

    Thanks for the advice.

    Why batts? After doing a little comparison, it seems they're more expensive and take a bit more work to get in to place. Is there something I'm missing?

    Is a vapor barrier required in my area?

  • energy_rater_la
    11 years ago

    batts are my prefrence.

    easy to move when you need to get to
    something rather than having to dig out
    blown insulation.

    cellulose is messy..messy to install
    messy every time you open the attic
    access.
    while I can deal with the mess once,
    I wouldn't want to have to deal with
    it every time I went into the attic.
    just my personal experience.
    I won't work in homes with cellulose.
    messes up my lungs for weeks.

    I'm not sure of vb location for your
    area. check with local codes for specifics.

    best of luck

  • _sophiewheeler
    11 years ago

    I absolutely loathe blown in insulation of any kind if you're going to do any work on the home. Batts are just easier for an homeowner with an older home who is likely to want to add additional lights, or other electrical, or renovate anything at some point. They are much easier to move out of the way, do your project, and then re-use. If you're building new, and have added chases to be able to run stuff from one end of the attic to the other, then blowing in fiberglass would be fine. But if you're gonna be crawling around in the attic, and using it for storage, I'd do batts in a heartbeat.

    You most likely need a vapor barrier in your climate as the first layer, with it facing down. However, the MOST important thing is air sealing to keep hot air away from your conditioned air. My cousin had what he thought was a leak coming though a recessed light. He couldn't figure out why, since there was no plumbing pipe there, and the roof was decent. Upon further investigating, there was quite the air penetration and the hot moist exterior/attic air was coming into contact with the cool air conditioned air of the home and causing condensation to form and drip down.