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strouddljs 11-08-2009 08:12 PM

adding attic insulation to existing insulation
 
We are trying to add batt insulation to our existing 5.5" cellulose insulation. My husband got R19 faced insulation. We understand that the vapor barrier may promote moisture. Will that be a problem if we install the insulation with the vapor barrier facing up. Please advise:confused1::help:

Bob Mariani 11-09-2009 04:27 AM

then you will have a vapor barrier at top of the insulated space and one at the bottom. Sooo... moisture will be trapped... insulation ruined.,.. mold grows.... If you cannot buy the unfaced insulation that you should be using, then cut slots in the paper face to allow the insulation to breathe.

strouddljs 11-09-2009 06:30 AM

attic insulation to existing insulation
 
Thank you. I will cut slats in the vapor barrier than exchange the rest of the insulation for unfaced.

Lesley

Gary in WA 11-09-2009 01:59 PM

"I will cut slats in the vapor barrier" ---- as Bob said, slots ----- actually remove some of the facing, 3" down the middle. Not just slits with a knife which wouldn't do much as the moisture laden air is not forced through, but slowly rises from below. After the new install the slits would close all but the 1/16" hole from the blade, not nearly as effective as removing v.b. material to let the warm, moist air rise. I would pull all the paper facing off or paint the ceiling below with a vapor retarding paint (oil), especially over a bathroom, laundry, or kitchen (water source).
Be safe, Gary

strouddljs 11-09-2009 05:06 PM

adding insulation to existing insulation
 
Thank you.


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