Unvented Attic Problems

Heat and moisture buildup in an attic cause predictable but different problems in hot and cold climates.

Unvented attic problems.

Unvented attics do not experience such problems. Attic ventilation myths that are off the charts 1. Heat is thus less likely to escape into an unvented attic from hvac equipment and if it does it will remain within the conditioned space. Here is a sampling.

When it s hot outside the sun beating down on the roof can increase the temperature in the attic. Among the early promoters of conditioned attics was joe lstiburek a principal of the building science corporation. Lots of gba readers have posted reports of this type of problem. Just like properly sizing your furnace and air conditioning unit you want precisely.

Unventilated attics can help to mitigate energy loss through leaky ducts or ceiling fittings. Roof vents are for warmer climates. Too many people believe the importance of roof ventilation is to increase energy. Areas with hot summers and cold winters can suffer the effects of both.

The intent of this brief is to provide code related information about controlling moisture in unvented attics by installing a vapor diffusion port vent that would convey water vapor from an unvented attic to the outside when air permeable insulation materials are installed and can be verified as being in compliance with the related codes and standards for residential construction. An unvented attic is conditioned space and won t be subject to the extremes of temperature common to vented attics. Unvented conditioned attics were quite rare before the 1980s.