How to Install Fiberglass Insulation in Your Attic

When installing fiberglass insulation in your home, be sure to put the paper or foil vapor barrier facing toward the heated and cooled living area of the home (down in attics, up under floors, in on walls) to prevent condensation from occurring.

If you are applying an additional layer of fiberglass insulation to your attic, use unfaced insulation on top of the existing insulation to keep from trapping moisture between the layers.

Watch this video for more information. 


Further Reading

26 COMMENTS

  1. i have 12″ of insulation in the attic, problem where a contractor put in the stove vent the snow has been melting, i added some insulation but this problem is still there, i could not get to the suffit area to put insulation on top of the pipe and i i did i would be blocking off any venting from there, actually the area they put the outside vent at that location is blocked, can i stuff that 1 section with insulation? i never noticed this until i moved upstairs in the garage and been like this for a long time.
    thanks mike

  2. I just seal coated my driveway. I used a broom like bristle brush. It dried and you can see the streaks. From a distance it looks great. Question? Can I use a paint roller attached to a long handle and go over the driveway again to remove the brush streaking?? Will it work?
    Thanks. Paul

  3. This whole insulation installation is very, very confusing. The video above shows that the fluffy side of the insulation is facing up. When the recommendation is to put the fluffy side down with the paper part facing the ceiling. So why did this guy in the video have the paper side down towards the floor and the fluffy side up. Don’t forget we are homeowners who needs to understand in layman terms. Show us and tell us as if we have no common sense, because we don’t.

    • Hi Cheryl,
      The paper facing on insulation has an asphalt layer which acts as a vapor barrier. You only want one vapor barrier in your attic, and it should be as close to the ceiling as possible to prevent warm, moist air from coming up from the heated house and condensing when it hits the cold air in the attic. So if you’re installing insulation in an attic that doesn’t have any, used faced insulation and put the paper side down toward the ceiling. If you’re installing additional insulation in an attic that’s already insulated, use unfaced insulation that doesn’t have a vapor barrier. You can find out more in our articles on How to Apply a Vapor Barrier to Attic Insulation and Which Way to Face Insulation. Hope that helps!

  4. Can you insulate the interior walls in an attic? I noticed in the above video that the walls are not insulated. My attic is the same.

  5. Hi Kate, It’s not necessary to insulate attic walls because it’s an unheated space. The idea is to keep the temperature inside the attic as close as possible to the outside air temperature. It makes much more sense–and cents–to insulate the attic floor, which in effective is insulating the ceiling of the rooms below. That way, you block heated air (and air-conditioned air) from escaping through the ceilings and leaking into the attic. Hope this helps. Good luck!–Joe T.

    • Hi Adam,
      When your attic doesn’t have any insulation, place the facing down toward the living space. In mild climates a vapor barrier isn’t necessary, while in colder climates it is to prevent condensation from forming in the insulation during the winter.

  6. With a vapor barrier present won’t the moisture collect on the floor boards and create mold? House is in southeast pennsylvania. Summers in the 90s and winter in the teens

  7. What are your thoughts on the Attic Tent and how much does it really help at saving on heating and cooling cost? I live in Louisiana and purchasing a townhouse with attic stairs.

  8. We currently have blown fiberglass insulation in our attic. We want to increase the insulation. Must we use more blown insulation, or can we add rolled insulation on top of what we have.

    • Rolled insulation is fine to use, just make sure you get “UNFACED” insulation. In other words, get the rolls that have no paper backing on them. I would also roll it out so it is perpendicular to the existing ceiling joists.

  9. I only have four inches of insulation in my attic. I am going to put a four foot runway of boards down the middle of the attic so I have a way of getting around. If I add at least 8 inches more of roll or blown insulation how do I put insulation over the boards so I have access later to the attic?

  10. What kind of Insulation did you use in the a crawl space..How is the best way to do it.. I have concrete floors.. Thank you

  11. Thanks for the video but I noticed your guy failed to mention what to do when there’s wiring in the rafter/joist bays where you’re installing the finerglass batts. To his left is knob and tube wiring running along the rafter and behind him is knob and tube running across. What to do? Install the insulation as he suggests regardless?

  12. I have beach cottage 0n cape cod ma,, can I put insulation (attic ) in between roof rafters, to save on my heating bill, If so should the paper be facing the in side of the attic. or use craft paperless or (will I create a sweating /moisture problem??? $$$ can’t afford blow foam $$$

  13. My attic space in the home that I recently moved into is completely open including over the garage space. I just noticed that there is no insulation over the garage. Should I add insulation over the garage? I was thinking if there was a wall in the attic separating it from the garage, it wouldn’t be necessary but since there is no wall, I should do it right? I have been finding conflicting information on this. Thank you for your suggestions!

  14. i live in phx az and i insulated my garage ,now i was told the paper side is top side ,now looking on internet i read paper side is down please help me witch is up

    • The National Electric Code prohibits installing insulation that comes in contact with knob-and-tube wiring, so we don’t recommend this.

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