Tim writes from Gibsonia, Pennsylvania: "I live in the greater Pittsburgh area, and I have R-38 of blown-in insulation in my attic. The blown-in insulation has drifted due to wind coming in the vents. Any suggestions? What would the payback be if I added 6" of blanket on top of blown-in?"

Answer: Attic vents should be placed high enough to keep wind off of the blown-in insulation. If your vents are placed low and cannot be moved, perhaps a small baffle under the vent will direct the air flow away from the insulation. Blocking or baffles should also be used at the eave between the top plate and the vent to keep air currents from disturbing insulation in that area.

Regarding your payback question, there are too many variables and unknowns to precisely quantify the return, but comparing what you have with DOE recommendations for your part of the country suggests that adding insulation will be beneficial.