Unvented Attic Space

In cold climates attic ventilation is a common method to remove humid air.

Unvented attic space. The unvented attic is indirectly conditioned space since heat and moisture transfer occurs through the top floor ceiling particularly if the ceiling is not airtight. Building america research has demonstrated unvented conditioned attics can substantially improve energy performance while allowing home builders to continue locating hvac systems in the attic space. Air does not flow into the soffits and does not flow out of ridge or gable vents. The entire attic becomes conditioned space eliminating drafts and temperature fluctuations.

Unvented attic roof designs have the advantage of providing conditioned spaces for ductwork and air handlers. An unvented attics is one where the air vapor and thermal controls are installed at the roof deck. Modifying the attic to create an indirectly conditioned attic space with icynene can significantly reduce energy consumption. The unvented attic space is completely contained within the building thermal envelope.

However they require different approaches in different climate locations. Unventilated attics can help to mitigate energy loss through leaky ducts or ceiling fittings. The unvented attic space is completely contained within the building thermal envelope 2. No interior class i vapor retarders are installed on the ceiling side attic floor of the unvented attic assembly or on the ceiling side of the unvented enclosed rafter assembly.

Section 1203 3 says unvented attics where ceilings are applied directly to the underside of the roof framing members are permitted when all of the following conditions are met. No interior class i vapor retarders are installed on the ceiling side attic. In hot climates unvented attics are ideal where hvac equipment and ductwork are located in the attic. The energy savings touted by unvented attics can be as high as 20.

This system can help you avoid. Adding unvented attic insulation like spray foam seals the building envelope and stops airflow. No interior vapor retarders are installed on the ceiling side attic floor of the unvented attic assembly 2009 irc. The unvented attic space is completely within the building thermal envelope.

Making the attic a conditioned space means the space will be the same temperature as the rest of your home.