Adding Blown Insulation Over Existing Attic Batts

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Jennifer asks:
Can I install cellulose blown in insulation over batt insulation with tears in the vapor barrier? I was air sealing my attic and had to tear the vapor insulation to reach some of the bypassing. Do I have to remove all of the batted insulation or can I just lay the insulation on top?


If the vapor retarder is correctly positioned, that is under the insulation directly against the ceiling, you can blow insulation over the batts.  In fact, the batt and blow approach is a recommended and common technique for overcoming the endemic problems of batt installation. The fact that you had to cut the batt facing (vapor barrier you mentioned) suggests to us the batts may have been installed with the facing up.  If so, blowing insulation over the batts would compound an incorrect installation by sandwiching a low perm layer between two layers of insulation. If the batts are correctly positioned with the facing down and are in good condition, blowing insulation on top of the existing insulation is a good idea.

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