Vaulted Ceiling Insulation Rigid Foam

We re roofed our house this summer and found a lot of damage over our family room with a vaulted ceiling.

Vaulted ceiling insulation rigid foam.

The roof rafters are 2 x 6 i was planning to do 2 inch rigid polyiso super tuff r back to back in the rafter bays with foil facing the interior. Most local building codes require that rigid foam boards made from polyurethane or polystyrene be covered with a 15 minute fire rated thermal covering if they are used on the inside of the house. Polyiso provides one of the highest r values per inch of any rigid insulation r 6 at 1 inch. We are planning to use r30c insulation which is denser for cathedral ceilings.

Rigid foam on roof sheathing with air permeable insulation between the rafters. Attics and cathedral vaulted ceilings. While it is possible to use a permeable insulation open cell foam fiberglass or cellulose in an unvented cathedral ceiling it is risky. Closed cell foam ceiling insulation in a vaulted ceiling offers substantial advantages over open cell.

Vaulted ceilings require venting as well as insulation. The terms refer to whether the foam bubbles burst during curing making the foam soft like a sponge or remain intact and firm like those in the rigid foam panels at home centers. Johns manville aptm foil faced insulation sheathing board is an excellent choice for insulating attics and cathedral vaulted ceilings. When applied to the.

Seal the insulation or the ceiling surface below against air leakage. In this case the rigid foam can be thinner than when it s used alone. Insulating a vaulted ceiling is similar to insulating exterior walls with one notable difference. Place the insulation between the rafters or below them.

We replaced the plywood and are now redoing the underside. The roof has a roof ridge vent and ventilation holes in the soffits. Do no use a vapor barrier under the. You don t want moist air leaking into the roof cavity.

About the only time you are likely to add rigid insulation to a ceiling is in a retrofit of a cathedral ceiling. I bought an old ranch on long island climate zone 4 with no insulation and i vaulted the living room and den ceiling they are next to each other. How to attach rigid insulation to ceilings. Code specifies the minimum r value of the rigid foam layer.

Use closed cell spray foam closed cell foam board extruded polystyrene such as dow styrofoam or foil faced iso board. I have a dilemma. Thin metal or rigid foam the baffles. Rigid foam also can be installed above the roof sheathing in tandem with air permeable insulation between the rafters.

Rigid foam boards used in ceiling insulation are often made of either cellulose fiber fiberglass polystyrene or polyurethanes. Regular ceilings are likely to be under.