Unvented Attic Foam Insulation

With it the orientation and type of insulation applied to the top of the building enclosure has changed from the traditional way and so temperature and moisture conditions experienced by various assembly elements will be impacted.

Unvented attic foam insulation.

The foam insulation used for unvented attics stops air movement and with it the transport of moisture. The insulation extends down the roofline to the rim joists and soffit areas as well as on gable wall ends. To some unvented attic construction using spray foam insulation is a fairly new approach in home building. Any hvac equip ment located in the attic is within the conditioned shell of the house which also cuts energy losses.

Spray foam in unvented attics intended for regular use helps. This is done by using what is referred to as air impermeable insulation such as rigid foam board or spray foam. Unvented attics sometimes called sealed enclosed or encapsulated attics feature insulation on the underside of the roof decking rather than on the attic floor. Two acceptable methods for insulating an unvented attic assembly in all climates are as follows.

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. Air impermeable insulation typically spray foam installed to the underside of the roof sheathing. Using spray foam insulation in an unvented attic application both low density open cell and medium density closed cell spray foam can be used in an unvented attic to provide the needed thermal resistance and airtightness.