Insulating A Vented Attic

Install insulation along the underside of the roof deck of an unvented attic rather than on the ceiling deck of a vented attic for either of two reasons.

Insulating a vented attic.

The attic space becomes indirectly conditioned as a result of the air leakage heat transfer and. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. Square footage of your attic. One huge benefit of the spray foam insulated attic is that conditioned air leakage from the ac furnace duct system is contained and used to condition the attic.

Type and material of your insulation. The recommended ventilation ratio to provide for vented attic assemblies when an air barrier is present is the 1 300 ratio as specified by most building codes. However in a traditionally insulated attic insulation on the ceiling the attic is vented. Hot air exhaust vents located at the peak of the roof allow hot air to escape.

If you don t want to use sips or nailbase read this article tolearn the four basic approaches to insulating unvented roof assemblies. 1 300 ventilation ratio recommended. Insulation is used in an attic for cross ventilation to minimize potential for moisture accumulation and condensation to help energy savings and moisture control. When we seal the attic with spray foam it s as tight as a butter tub.

Contractor or insulation installer s fee. Attic fans are intended to cool hot attics by drawing in cooler outside air from attic vents. When hvac equipment is in the attic insulation and an air barrier at the roof line brings that equipment within the conditioned enclosure envelope thereby allowing it to operate in more favorable temperature and humidity conditions without air leakage and heat loss gain directly to the exterior. Roof insulation thermal resistance at roof perimeter should be equal or greater to thermal resistance of exterior wall.

About attic ventilation natural attic ventilation. In an unvented attic assembly air impermeable insulation is applied directly to the underside of the structural roof deck and is tied into the insulation located in the walls so that the roof system becomes part of the insulated building enclosure. Intake vents located at the lowest part of the roof under the eaves allow cool air to enter the attic. According to home advisor insulating your attic can cost between 1700 to 2100.

To provide an unvented conditioned space for locating hvac equipment in the attic and or to provide a continuous thermal barrier for designs that have complex coffered ceiling planes and or numerous penetrations for lights speakers vents soffits etc which make it difficult to achieve an airtight ceiling plane. Unvented roof assemblies should be insulated either with air impermeable insulation rigid foam or spray polyurethane foam or with a combination of foam and air permeable insulation.