We are purchasing a 1968 A-frame house that has a leaking roof. We will replace it, and we're not sure if we're going to do metal or asphalt shingles. Right now the layers are, from the inside, 6" beams app. 48" OC, 1" pine t&g, tar paper, shingles. Missing from that list is any kind of insulation, and we're hoping to fix that. How do we insulate a timber frame house?