Return to the Home Repair Forum | Post a Follow-Up

Upside down attic insulation

Posted by bfg9k (My Page) on
Tue, Sep 7, 10 at 11:40

Our 1500 sq ft ranch's attic is very under-insulated. During last summer's moving-in renovations all of the 55 year old windows were replaced, all cracks caulked, etc., making it pretty free of drafts. However the heating bills were still $400/month with the thermostat at 66F (oil heat - 30 year old furnace). The attic has a double layer of 4" fiberglass batts in place. The bottom batt is kraft-paper down, then the top batt is kraft-paper up. There's no vapor barrier, but during the renovations we used copious quantities of BIN shellac primer on the ceilings (to seal in cigarette smoke residue, ick) and I understand that makes a fairly decent moisture barrier.

If I were to go and add a whole bunch of blown in cellulose insulation to bring the R value up to around 40, should I either remove the top layer of batts, flip them over, or leave them alone?

Follow-Up Postings:

RE: Upside down attic insulation

How is the attic ventilated, what is the attic used for, are there any HVAC ducts in the attic, what is the slope of the roof and how high is the ridge above the attic floor?

The purpose of kraft paper facing is to form a vapor retarder if it is stapled to framing at its edges. the purpose of attic ventilation is to allow moisture to escape from the attic space.

RE: Upside down attic insulation

The attic has a full ridge vent and gable end vents,the, don't know offhand. Let me guess - 14 degrees with a 5' high center and 40 foot width house. There are no HVAC vents anywhere in the attic (or the rest of the house). The batts are not stapled to anything, as I found when I installed a whole house fan earlier this year.

RE: Upside down attic insulation

A rodge vent needs soffit vents to work properly. Gable end vents will only allow half of each end of the attic to vent.

Adding/clearing passages for soffit vents will increase the attic air flow and heat transfer tremendously.

RE: Upside down attic insulation

can't have two vapor barriers within a bldg assembly.
condensation forms between the two vb's when attic dewpoint is reached.
remove paper backing off top batt and install blown
might be easier just to remove top batt and blow insulation

best of luck

RE: Upside down attic insulation

Go up there with a utility knife and slit the upper most paper or take it off, what ever is easier.

RE: Upside down attic insulation

You do not need any implement to remove the kraft paper, simply peel it off.

RE: Upside down attic insulation

Before you add any more insulation I would be meticulous and go through and seal any penetrations in the ceilings, every wire hole, plumbing chase, electrical box, etc. Make sure the access door has insulation/sealing equal to the ceilings. The R-value assumes no air movement between the areas. Insulation is all about the details. If you miss 1% of the area, you lose alot more than 1% of the insulating value. Its like having a 1% hole in your bucket, you lose more than 1% of the water.

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Home Repair Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here