High Humidity Unvented Conditioned Attics

Identify the sources of moisture in unvented conditioned attics with elevated indoor humidity levels.

High humidity unvented conditioned attics.

In the early 1990s construction of unvented attics became popular especially for structures in warmer climates. Still got high humidity. Recommend remedies to reduce the chance of sheathing rot in unvented attics with high moisture levels. A dehumidifier can remove it.

If you convert your vented unconditioned attic to an unvented conditioned attic by installing open cell spray foam on the underside of your roof sheathing you may be surprised to discover. High humidity in unvented conditioned attics. Most of these attics stayed dry. You can do that by directly conditioning the attic with supply air by blowing conditioned air from the house into the attic by exhausting air from the attic to outdoors or by using a dehumidifier.

Decide whether open cell spray foam or closed cell spray foam is preferable when creating an unvented conditioned attic. Wood roofing panels endorsed by the apa usually contain an in service water content of between 4 and 16. The typical construction scenario involved the use of low density open cell spray foam insulation for the thermal barrier at roof deck and duct work installed in the unvented attic space. After from sealing things up and fixing your pressure balance this is usually the best solution to high humidity in a spray foamed attic.

In theory if you install a small exhaust fan in the gable wall of an unvented attic along with a passive duct or grille that allows conditioned air from the floor below to enter the attic as makeup air the humid air in the attic will be exhausted and will be replaced with less humid air from the home. It wouldn t solve the problem of high humidity in the attic though. If you don t do that you ve got to reduce the amount of water vapor in the attic. Put a dehumidifier up there plug it in set it between 50 and 60 rh and forget about it.