Kathy writes from Canandaigua, New York: "I have an old house with a cedar shingle roof. All is well except the area over the open porch where the ceiling is leaking but the roof shingles don't seem to be wet. There is tons of insulation over the porch roof which seems to be purposeless. Is there any advantage to insulating a roof over an open porch and could this be condensation coming from the warmed up insulation in a cold roof?"

Answer: It is common to insulate under the roof if the porch is heated or air-conditioned. The Federal Housing Administration (FHA) calls for a minimum one inch of ventilation space under a roof deck (with soffit to ridge vents). The purpose of the venting is to draw out moisture like you have described.