Replies

1. 
   Dana1 | Sep 29, 2015 09:10am | #1

   In climate zones 5 & 6 you don't need a ceiling vapor barrier. The ceiling needs to be air tight however. Soffit to ridge venting is preferred, with the cross section of the soffit vent area 30-50% larger than the ridge vent area. Larger soffit than ridge vent area keeps the pressure difference between the conditioned & attic spaces at the ceiling plane limited, so as not to drive infiltration through the ceiling leaks with the stack effect of the attic height.

   Attic exhaust fans are a universally BAD idea in reasonably insulated houses, especially in cold climates. Depressurizing the attic draws conditioned space air into the attic through any & all leaks in the ceiling plane, which increases the heating & cooling loads. In hot climates small self-powered attic ventilators can sometimes reduce total energy use in houses with sub-code insulation levels, provided there is sufficient cross section to the soffit or gable vents to limit the amount of depressurization.

2. GBA Editor
   Martin Holladay | Oct 07, 2015 02:27pm | #2

   Chris,
   Dana Dorsett gave you good advice.

   For more information on these issues, see:

   Do I Need a Vapor Retarder?

   All About Attic Venting

   Fans in the Attic: Do They Help or Do They Hurt?