Unvented Attic Problems

Too many people believe the importance of roof ventilation is to increase energy.

Unvented attic problems.

More attic ventilation is good. 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. Here is a sampling. The energy savings touted by unvented attics can be as high as 20.

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. Among the early promoters of conditioned attics was joe lstiburek a principal of the building science corporation.

Unvented conditioned attics were quite rare before the 1980s. Areas with hot summers and cold winters can suffer the effects of both. When it s hot outside the sun beating down on the roof can increase the temperature in the attic. Lots of gba readers have posted reports of this type of problem.

Unvented attics do not experience such problems. However if moisture is able to enter the unvented attic space it may lead to roofing panel issues. 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.