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hippityhoppy

Insulation - remove paper on fiberglass batt in attic install?

hippityhoppy
9 years ago

The fiberglass batts in my rancher-style home's attic were installed with a paper liner facing upwards, towards the attic roof. There is one layer of fiberglass batts, about 4" in height.

Should the paper liner have been lain down facing the attic floor?

If it is incorrectly laid, is it OK to place more fiberglass on top of the current fiberglass batts anyway, either blown-in or laying down more fiberglass batts? I am reluctant to remove the current fiberglass because it is, afterall, insulation.

The current fiberglass' paper could be peeled off if it is a problem. But that's a bothersome task. Would peeling off the paper be necessary or can it remain?

The recommended insulation level for most attics in Maryland is R-49 (or about 15-20 inches, depending on the insulation type). So, adding more seems better unless the way it is added creates another problem, e.g., moisture trapped under the paper causing the fiberglass to get moldy.

Thank you.

Comments (13)

  • mike_home
    9 years ago

    The paper acts a moisture barrier. It should have been installed face down towards the conditioned space. By having the paper on top there is a potential of trapping moisture in the insulation and ruining the insulation.

    I think it would be easier to flip the insulation over rather than ripping off the paper. If you add a second layer it should be without the paper. It would be good if you install the second layer perpendicular to the first.

  • callights
    9 years ago

    The paper should always face the side that is "warmer" for most of the year. In MD, that means the paper should be down. In Florida, for example, the paper should be up.

    Do not sandwich paper in the middle of an insulation stack.

  • hippityhoppy
    Original Author
    9 years ago

    Thank you for your expert advise about the placement of the kraft paper. I understand that the way the kraft paper is currently installed would create the possibility of condensation if it is covered by additional insulation. So, the paper will be peeled off and discarded.

    Upon closer examination, I've found a couple of inches of an older insulation material, (rockwool, probably), under the current fiberglass batts. Perhaps its' presence is why the batts were not installed with the paper down.

    Removing the kraft paper is an unwelcome task. I appreciate your explanation as to why it is important to remove the kraft paper.

    I'm dragging out long-sleeved shirts and gloves for cover.

    What type of face mask protects one from breathing in fiberglass particles? Do eyes and ears need some sort of protection too?

    Thank you.

  • mike_home
    9 years ago

    What could happen is warm moist air from the house will rise up to the attic and create water condensation on the bottom of the paper. This will cause the insulation to become wet and eventually ruin it.

    A simple mask from Home Depot is fine. This is fiber glass, not asbestos. Eye protection is not needed unless you are sensitive to fiberglass. I still think it would be easier to flip the batts over, but that is something for you to decide as you start the project.

  • hippityhoppy
    Original Author
    9 years ago

    Thanks, Mike,
    If there is a couple of inches of rockwool under the fiberglass batts, is it still OK to flip the fiberglass?

    Would that not "trap" the rockwool under the fiberglass paper and allow for any condensation to accumulate and put mold on the rockwool?

    I appreciate your advise. Very helpful.

  • ionized_gw
    9 years ago

    "If there is a couple of inches of rockwool under the fiberglass batts, is it still OK to flip the fiberglass?"

    You need to be certain of the relationship between the condensation plane and the drying side of the vapor barrier. The drying side has to be on the same side of the vapor barrier as the condensation plane.

    In some locations, it can be tough to figure out what to do. It gets reasonably cold all over MD, but you have pretty high dew points in the summer too.

    This post was edited by ionized on Thu, Dec 11, 14 at 14:36

  • energy_rater_la
    9 years ago

    "If there is a couple of inches of rockwool under the fiberglass batts, is it still OK to flip the fiberglass? "

    no. just remove the paper from the batt & leave in place.
    put new unfaced bats on top.
    in my attic I filled the joist bays with batts then
    came back across with another layer of unfaced
    batts. can't see the joists now, and it helps to
    reduce thermal bridging.

    be safe up there & watch where you step.

    best of luck

  • mike_home
    9 years ago

    I agree with Energy Rater. If you are going to leave the rock wool insulation then flipping the fiberglass batts can still trap moisture in the first layer of insulation. Stripping off the paper is the correct way.

    Have figured out what is the total R value of the two layers? You want a minimum of R30. Increasing it is good and fairly inexpensive if you do the work yourself, but what I have found you quickly hit the law of diminishing returns.

  • hippityhoppy
    Original Author
    9 years ago

    Thanks Ionized, Energy_Rater and Mike_Home,

    As there is no compelling reason to remove existing insulation, it seems best to leave what's there in place. But the kraft paper has to be removed.

    These are R-values for the two products: Fiberglass, 2.2 to 2.7 per inch; Rockwool, 3.0 to 3.3 per inch. Using the median number of both, I estimate the current installation's R-value at 16.

    CURRENT INSULATION'S R-VALUE
    Fiberglass: 2.5R x 4" = 10 R
    Rockwool: 3.1R x 2" = 6.2 R

    To get up to 30R, another 14R is needed which is:
    5.6" of Fiberglass or
    4.5" of Rockwool.

    So, laying one batt will get close to 30 R which is adequate as Mike suggested.

    Is it OK to lay Rockwool on top of the current fiberglass (after the paper is stripped off)?

    Below is a link on how to dress for installing insulation. Fiberglass asks for more dress-up than does Rockwool...a different sort of date. ;-)

    This same website provided the R-values in the article on "How to compare f/g and r/w".

    Gosh, you've all been so helpful. I am very grateful. Thank you.

    Here is a link that might be useful: How to Dress for Working With Fiberglass Insulation

  • mike_home
    9 years ago

    The fiberglass insulation you have is probably 3.5 inches thick and rated as R-13. The rating should be printed on the paper.

    I have never used rock wool insulation, but for what I have read it used more for it's sound deadening features. It is more expensive than fiberglass and has about the same R value.

    I would suggest getting the R-19 fiberglass 15 inch wide unfaced rolls. I think it is easier to unroll a roll than having to open and position a folded batt. The batts are available in 23 inch widths so you may find it easier to work with them.

    I am sure you can find a YouTube video on good installation methods and tips. Take your time and remember you don't have to do the project in one day.

  • energy_rater_la
    9 years ago

    just wanted to add...I was in an attic today
    to test a bad bad foam install job.
    (3800 cfm of leakage in "unvented" attic ...LOL!)

    the insulation still on the floor
    was from floor of attic going up...
    2" cellulose
    R-13 batt (kraft paper UP!...never seen that!)
    8" of blown fiberglass.

    foam company didn't move insulation back
    from soffits/eaves, so none of the soffit
    ventilation was sealed off.
    mess of an install...

    but the install & layers of insulations reminded
    me of this thread.
    I had to laugh because I'd
    just posted that I'd never seen fg batts installed
    with paper facing attic space. never say never!

  • hippityhoppy
    Original Author
    9 years ago

    That's oddly coincidental, energy_rater.

    I'm proud to be in the vanguard of the paper-up movement! ,,,, foolish as we are. :-( We are a subset of the make-more-work program.