Jeff writes from Stanhope, New Jersey: "I want to reinsulate my attic which already contains R30 blown insulation. I do not want to use blown insulation I would like to use R25/R30 rolled insulation. Which insulation would work best for this installment, faced, unfaced, plastic wrapped?"

Answer: The recommendation when adding attic insulation is always to use "unfaced" insulation. You will be putting the new insulation on top of existing insulation and you don't want a second vapor barrier in the middle of your insulation.

If there was no insulation in the attic you could install insulation with a vapor retarder and place it toward the warm side in heating climates - in your case on the bottom of the insulation in the attic. Since you have insulation in the attic, there is presumably already a vapor barrier in place under the insulation and a second one is not needed. If the ventilation is sufficient - such as with a vented soffit and full ridge vent - some counties do not require a vapor barrier under insulation in the attic if the floor is flat, i.e. not over a vaulted or cathedral ceiling.