Best Way To Insulate 2x8 Cathedral Ceiling

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Best way to insulate 2x8 cathedral ceiling.

Air permeable insulation such as fiberglass batts dense packed cellulose or blown in fiberglass can t be used alone for an unvented assembly since these types of insulation can allow moist indoor air to reach the cold roof sheathing leading to condensation or moisture accumulation. Although many view this as a new method as stated previously many contractors have been doing this for years. One of the best options would be spray foam insulation here s why. In fact as far back as 1975 ncima standard n 301 75 stated.

A cathedral ceiling is often difficult to insulate as they leave very little room for ventilation which is needed to keep the insulation dry. Soffit vents and ridge vent are available. In fact when the only space you have is that left by a 2x8 or even a 2x10 you really can t do a perfect job of both. Use closed cell spray foam closed cell foam board extruded polystyrene such as dow styrofoam or foil faced iso board.

Ted what is the best way to insulate a cathedral ceiling with 6 16 of space between the drywall and roof sheathing. A cathedral ceiling is a sloping and pointed ceiling which is usually high and open. Insulating an unvented cathedral ceiling. Utilizing cellulose insulation contractors blow the cathedral ceiling cavity completely full and do away with the need for outside ventilation.

Although the gba website already contains many articles on the topic we continue to receive frequent questions about the best way to insulate a cathedral ceiling. Cathedral ceilings are a feature in many homes that add to value to the house because the high ceiling tends to make rooms look larger. Seal the insulation or the ceiling surface below against air leakage. It s therefore time to pull together as much information on the topic as possible and publish it in one place to clarify the building science issues and code requirements.

An unvented assembly can perform well but it s important to get the details right to avoid sheathing rot. Place the insulation between the rafters or below them.