The choice of the venting approach is up to the designer.
Finishing an unvented attic.
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.
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.
Unvented attic system pros and cons.
The attic space becomes indirectly conditioned as a result of the air leakage heat transfer and vapor diffusion through the ceiling.
Closed cell is a vapor retarder meaning water from a leak could be trapped against the roof sheathing.
Adding unvented attic insulation like spray foam seals the building envelope and stops airflow.
Unventilated attics can help to mitigate energy loss through leaky ducts or ceiling fittings.
As a result you can reduce the temperature in your attic by a lot anywhere from 120 degrees to around 95 during peak summer.
During the spring summer and fall relative humidity rh in a spray.
The irc has permitted unvented conditioned attics since 2006 with certain requirements.
But in many spray foamed attics it can be hard to manage humidity.
The unvented attic system or conditioned attic is the new way to make your attic energy efficient.
Code requirements vary across the country.
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.
The energy savings touted by unvented attics can be as high as 20.
However the designs need to be climate sensitive.
Both vented and unvented attic roof designs can be used in all hygro thermal regions.
Once an unvented roof is finished it s awfully damn difficult to notice roof leaks.
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.
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.
The roof deck in an unvented attic must be exceptionally airtight.
I have a shop in my attic for some of my hobbies and it get s very hot in the summer.
Control of ice dams moisture accumulation and heat gain can be successfully addressed by both vented and unvented attic or roof design.
This air seal will help to make your home more energy efficient.
I have large attic with ridge vents and screened vents at either end of the attic to maintain air flow.
