Vaulted Ceiling Insulation Rigid Foam

Vented ceiling across rafters.

Vaulted ceiling insulation rigid foam.

About the only time you are likely to add rigid insulation to a ceiling is in a retrofit of a cathedral ceiling. While it is possible to use a permeable insulation open cell foam fiberglass or cellulose in an unvented cathedral ceiling it is risky. Polyiso provides one of the highest r values per inch of any rigid insulation r 6 at 1 inch. We replaced the plywood and are now redoing the underside.

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. Seal the insulation or the ceiling surface below against air leakage. Use closed cell spray foam closed cell foam board extruded polystyrene such as dow styrofoam or foil faced iso board. Place the insulation between the rafters or below them.

Rigid foam boards used in ceiling insulation are often made of either cellulose fiber fiberglass polystyrene or polyurethanes. In this case the rigid foam can be thinner than when it s used alone. This approach relies on a near perfect air and vapor barrier on the house side of the ceiling cavity to keep moist household air and water vapor out of the roof cavity. When applied to the.

We re roofed our house this summer and found a lot of damage over our family room with a vaulted ceiling. Code specifies the minimum r value of the rigid foam layer. Closed cell foam ceiling insulation in a vaulted ceiling offers substantial advantages over open cell. Regular ceilings are likely to be under.

You don t want moist air leaking into the roof cavity. 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. How to attach rigid insulation to ceilings. Attics and cathedral vaulted ceilings.

Do no use a vapor barrier under the. Vaulted ceilings require venting as well as insulation. We are creating on site baffles with 1 rigid foam boards. I have a dilemma.

Thin metal or rigid foam the baffles. 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. We are planning to use r30c insulation which is denser for cathedral ceilings. Rigid foam also can be installed above the roof sheathing in tandem with air permeable insulation between the rafters.

The roof has a roof ridge vent and ventilation holes in the soffits. Insulating a vaulted ceiling is similar to insulating exterior walls with one notable difference.