Clearing the air

Proper attic ventilation is a significant part of a quality roof system

Attic ventilation is one of the most widely publicized yet misunderstood concepts in the roofing industry. As a result, many attics fail to have proper ventilation or may not be vented at all. This is unfortunate because attic ventilation, when required, is an important component of a quality roof system. To help roofing professionals understand ventilation issues, I will discuss NRCA recommendations, some industry design guidelines and a sampling of available ventilation products. (For the purposes of this article, it is a given that an attic space should be vented.) I also will provide information about manufacturers and their related products and recommendations as a service to readers. Inclusion of a manufacturer's product or recommendation in this article does not imply endorsement from NRCA nor does NRCA possess or maintain any information about these products' performance records.

Attic ventilation is needed for two primary reasons:

  • To lower attic temperatures: lowering attic temperature reduces air-conditioning energy costs and roof deck temperature, optimizes a roof covering's service life (such as asphalt shingles) and minimizes ice damming.

  • To promote the removal of excess moisture from attic spaces: removing excess moisture reduces corrosion potential, potential damage to building components, and mold and mildew growth.

Moisture from within buildings generally originates from one of two sources: construction processes or building occupancy activities.

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