Mike writes from Punxsutawney, Pennsylvania: "I am renovating an attic to make more living space. The newly created room will share an area where the existing roof and new ceiling connect. I put high density foam (cut to fit between the rafters) then supplemented the rest of the rafter space with rolled insulation to increase the total r value. A rafter vent was also installed on the roof sheathing between the rafters to insure air flow.

My question is - Is a plastic vapor barrier still needed prior to the drywall? Or does the high density insulation act as a barrier? I am concerned about making a moisture trap."

Answer: High density fiberglass insulation is not a vapor retarder. I am not sure what type of "high density foam" you have installed? Is it an Owens Corning product such as FOAMULAR® Extruded Polystyrene Insulation? If not, you may want to check with the manufacturer of that product.