JLC ??AUGUST 1991 Cathedral Ceiling Solutions Five contractors describe the sloped ceiling details that work best for them Few components in low-energy homes produce more diverse approaches — and more disagreement — than cathedral ceilings. The reason is simple: Trying to satisfy the insulation and ventilation requirements in such a tight space is a real challenge. It's often impossible to fit the required amount of insulation into the depth provided by a 12- inch rafter. A common solution for an R-40 ceiling is to use fiberglass batts between the rafters and then nail an inch of rigid insulation underneath the rafters. The seams of the foamboard can be taped