Best Way To Insulate 2x8 Cathedral Ceiling

Insulating an unvented cathedral ceiling.

Best way to insulate 2x8 cathedral ceiling.

Soffit vents and ridge vent are available. 16 gap at the peak 6 gap down near the wall top plate intersection. Ted what is the best way to insulate a cathedral ceiling with 6 16 of space between the drywall and roof sheathing. In fact as far back as 1975 ncima standard n 301 75 stated.

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. Although many view this as a new method as stated previously many contractors have been doing this for years. An unvented assembly can perform well but it s important to get the details right to avoid sheathing rot. One of the best options would be spray foam insulation here s why.

Bernice from midland ontario wants to know how to get more insulation into her vaulted or cathedral ceiling the common problem with structures like this that we call compact roofs is that there is not usually enough space for a lot of insulation and a lot of ventilation. Place the insulation between the rafters or below them. Utilizing cellulose insulation contractors blow the cathedral ceiling cavity completely full and do away with the need for outside ventilation. Use closed cell spray foam closed cell foam board extruded polystyrene such as dow styrofoam or foil faced iso board.

A cathedral ceiling is a sloping and pointed ceiling which is usually high and open. 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. 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. A cathedral ceiling is often difficult to insulate as they leave very little room for ventilation which is needed to keep the insulation dry.

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. It provides an open airy look and feel to the room and they are often in demand among home buyers.