Finishing An Unvented 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.

Finishing an unvented attic.

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. This air seal will help to make your home more energy efficient. The unvented attic system or conditioned attic is the new way to make your attic energy efficient. Unventilated attics can help to mitigate energy loss through leaky ducts or ceiling fittings.

The choice of the venting approach is up to the designer. 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. If you want you can even transform a spray foamed attic into a finished space. Can i put a small swamp cooler or ventless a c unit up there to cool it only to use while i am in my shop maybe an hour or two a couple times a week.

Both vented and unvented attic roof designs can be used in all hygro thermal regions. The irc has permitted unvented conditioned attics since 2006 with certain requirements. Code requirements vary across the country. Closed cell is a vapor retarder meaning water from a leak could be trapped against the roof sheathing.

During the spring summer and fall relative humidity rh in a spray. 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. However if moisture is able to enter the unvented attic space it may lead to roofing panel issues. The attic space becomes indirectly conditioned as a result of the air leakage heat transfer and vapor diffusion through the ceiling.

The roof deck in an unvented attic must be exceptionally airtight. But in many spray foamed attics it can be hard to manage humidity. I have large attic with ridge vents and screened vents at either end of the attic to maintain air flow. Once an unvented roof is finished it s awfully damn difficult to notice roof leaks.

Adding unvented attic insulation like spray foam seals the building envelope and stops airflow. As a result you can reduce the temperature in your attic by a lot anywhere from 120 degrees to around 95 during peak summer. I have a shop in my attic for some of my hobbies and it get s very hot in the summer. However the designs need to be climate sensitive.

The acceptance of unvented conditioned attics continues to grow among builders and building officials.