Unvented Finished Attic Insulation

This reduces latent air conditioning loads and provides further reductions in energy consumption.

Unvented finished attic insulation. When all of the insulation is tight to the roof deck the unvented enclosed rafter truss assembly or unvented attic is within the building envelope and the attic will be conditioned to have a similar temperature as the interior space. 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. The roof insulation and air barrier must follow the plane of roofing materials rather than diverge figure 2. An unvented attics is one where the air vapor and thermal controls are installed at the roof deck.

Unvented attics sometimes called sealed enclosed or encapsulated attics feature insulation on the underside of the roof decking rather than on the attic floor. This allows you to install your bulkheads above the ceiling plane without the need for spray foam insulation. Insulation approaches for unvented attics vary by climate. An alternate to spray foam insulation in an unvented attic is plenum trusses which allow you create a reverse bulkhead above the ceiling plane that is insulated.

Once you ve decided which type is best for you examine the material options and prices to home in on the right product. Only spray polyurethane foam can be used for this application as batt insulation will end up sagging and blown insulation simply can t adhere to the roof decking. The unvented attic space is completely within the building thermal envelope. Loose fill or batt the common term for blanket insulation.

Where the attic space is finished with drywall or other ceiling materials installed against the underside of the roof rafters while we prefer in floor insulation here we ll have to insulate the roof cavity between the rafters. Both can be added to uninsulated attics or layered over existing material. 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. A fundamental requirement of an unvented attic assembly is the use of air impermeable insulation on the underside of the unvented roof to prevent air infiltration and exclude airborne moisture from the attic.

The insulation extends down the roofline to the rim joists and soffit areas as well as on gable wall ends. 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. Un vented hot roof designs indoors finished attic. For diy attic insulation you ve got two choices.

Fibrous insulation fibrous insulation e g batt or blown in can be installed under the roof deck in the hot dry. An unvented attic is one which is not ventilated and this is important one where the ceiling has complete air vapor and thermal controls in place.