Reinsulating Attic

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  #1  
Old 04-02-07, 12:56 PM
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Reinsulating Attic

I have a mid-80s house that has very poor attic ventilation. I have mold on the sheathing (north side mostly, some on the west side) that is being cleaned and encapsulated by a mold company. The existing fiberglass batt insulation is being removed and will be replaced with new. I have a ridge vent being installed as well which when combined with the existing soffit vents should give me proper ventilation. For the new insulation should I install faced batts or unfaced with a poly barrier? I am very nervous about moisture in the attic given the mold problem I have so I was tending toward the poly barrier and unfaced batts. But in fixing the ventilation issues is the poly really overkill? It certainly will be more work to install.
And secondly I use the attic for storage. Is there any issue in using R30 in the non-floored areas and R19 in the areas I plan on installing the floor? I have 2x6 joists on the attic floor. Thanks.
 
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Old 04-02-07, 01:21 PM
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forgot to include:

soffit vents are continuous around the house.
roof is hip - north side is one of the short sides of the roof.
attic is about 1100 sq ft.
there is a powered attic fan in the roof but is only temp controlled. no humidistat.
 
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Old 04-02-07, 02:30 PM
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On a rework like this and all the insulation is out. first but the foam vents in the rafters at the plate . So air from the overhang can get in to the attic. Id put down a R13 paper side down to the ceiling. Then come in with a blow of cellulose for a tot of a R 30. Yes you can do some R 30 and some R19 its up to you
 
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Old 04-02-07, 03:58 PM
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Seal all gaps where warm, moist air can enter from below. If using faced batt insulation, facing goes down toward heated area below. The facing is the vapor retarder. Check with local building code office to determine the recommended minimum R rating for insulation in your area. Note: that's the minimum.
 
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Old 04-03-07, 07:49 PM
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Ed has the right idea. The cellulose will also fill up any gaps between the ceiling and the attic air space. You may not even need a vapor barrier between the ceiling and attic. Check with your codes.
 
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Old 04-03-07, 07:54 PM
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Ed is always on target with his advice, and please heed it, especially keeping soffit vents clear. Just wanted to add that it is important to seal any gaps that will allow warm, moist air from below to enter attic area. Make sure you do the proper calculations to assure that you have the recommended ventilation/SF of attic space. Again, your local building code office can be a great help to you. Their insulation recommendations are the minimum.
 
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