how to insulate a cathedral ceiling with no attic
I need insulation. In 14' x 24' Living Room, with a/c running - 78 in-82 degrees in lower area and 107-112 at peak of ceiling on the inside! I have 16' high vaulted ceilings with 5 1/2" H x 4"W exposed old growth redwood beams with a main beam made up of 3 redwood 2x10's nailed together and faced at the bottom end with a thin layer of redwood. Looks like when they built the house in 1957, they installed the sheetrock on the top of the beams (maybe between given the 5 1/2'" dimension- rest of house has old wood dimensions) and then lattice and wood shingles. The wood shingles were removed and replaced with plywood 4 x 8's, tar paper and shingles. They were shooting 3 1/2" nails through the sheetrock when they installed the plywood, so I know there isn't any space up there. The redwood is the only WOW factor in the house, don't want to loose them and am afraid of putting too much additional weight on the support of the house. Need something lightweight and inexpensive. Any ideas?