Upside down attic insulation

bfg9kSeptember 7, 2010

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?

Thank you for reporting this comment. Undo

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.

    Bookmark   September 7, 2010 at 12:06PM
Thank you for reporting this comment. Undo

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.

    Bookmark   September 7, 2010 at 12:14PM
Thank you for reporting this comment. Undo

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.

    Bookmark   September 7, 2010 at 12:23PM
Thank you for reporting this comment. Undo

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

    Bookmark   September 7, 2010 at 3:12PM
Thank you for reporting this comment. Undo

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

    Bookmark   September 7, 2010 at 11:16PM
Thank you for reporting this comment. Undo

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

    Bookmark   September 8, 2010 at 9:12AM
Thank you for reporting this comment. Undo

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.

    Bookmark   September 8, 2010 at 11:05AM
Sign Up to comment
More Discussions
Help With Siding Repair
I have a problem which is ... this: That is a slat...
home ventilation system (EZ Breathe)
Hello! Has anyone out there had the EZ Breathe Ventilation...
adjusting stop on lazy susan
Hi all, I have recently moved into an older home with...
what type of contractor needed for this?
What type of contractor is needed to replace a rotting...
Heating tool
Picked this for free at an estate sale. Wood burning,...
Sponsored Products
Natural Cedar Wood High-Low Planter
Signature Hardware
simplehuman Vertical Tension Shower Caddy
$129.50 | FRONTGATE
Arteriors Home - Drea Side Table - 6344
Great Furniture Deal
A19 Lighting | Grenada Downlight Wall Sconce
$99.99 | YLighting
"Upside-Down" Glass Leaf Lamp
$394.90 | Horchow
Melampo Floor Lamp by Artemide
$835.00 | Lumens
Crystorama Southport Collection 22" Wide White Ceiling Light
Lamps Plus
Hunter Green Upside Down Suet Feeder
$16.99 | zulily
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™