Ridge Vent . . . and Nothing But the Ridge

Can anyone convince me that this picture shows anything other than the fact that the ventilation provided here is effective only in the first five inches down from the ridge? And yes, there is continuous soffit venting that is baffled and open to the outside.

Views: 13023

Comment

You need to be a member of Home Energy Pros to add comments!

Join Home Energy Pros

Comment by Bob Mariani on December 29, 2011 at 3:30pm

Still more natural air flow should persist.  I believe the soffit venting is insufficient.  The air movement should be equal between the ridge and the soffit vents.

Comment by Ed Voytovich on December 29, 2011 at 2:55pm

Bob . . . I'll refer to the black snot as "mildew" in hopes of assuaging to the extent possible the anxiety of the homeowners and the desire of their lawyers for a new Mercedes.   

Thanks for pointing out the fact that the cut-out is somewhere around an inch or less on each side instead of the manufacturers' recommended inch and a half.  Still, could another 3/4" on each side make that great a difference?

There are no gable end vents, and the same pattern of mildew extends the entire length of the ridge.

I suspect that this condition is more typical than not of ridge vents.  When the wind blows across the roof  and the ever-popular Bernoulli's Law (http://scienceworld.wolfram.com/physics/BernoulliEffect.html) comes into play, the downwind side of the vent sucks air out of the attic.  I suspect that it is most likely to take the makeup air from the nearest source (which is the other side of the ridge) than from either gable vents or vents in the soffit.  My thinking is that the high-moisture conditions in this particular house created an interesting experiment, but I am grateful for other thoughts and possibilities.

Comment by Bob Mariani on December 29, 2011 at 1:52pm

Ed, is that mold on the discolored section of the sheathing?  The vent opening should have been larger.  Only a small air flow is occurring.  Also be sure no gable vents are still opened that will short circuit the soffit to ridge vent airflow.

Videos

  • Add Videos
  • View All

Twitter

Latest Activity

Kelly replied to Colin Genge's discussion What is the value of using a pressure pan to test outlets?
"Hi Colin, I like using the pressure pans at outlets to guide my inspections once I'm in the…"
12 hours ago
Leo Klisch commented on Home Energy Magazine's blog post Natural Gas is Becoming Less Attractive
"It seems a bit wasteful to use NG for such a low temperature application as space heat. If a heat…"
13 hours ago
HomeWiz posted photos
14 hours ago
Kobus Niemand commented on Jim Gunshinan's blog post A Healthy Home and a Healthy Bottom Line
"Thanks for the download! Great paper,  Homes receiving EE can experience increases in radon…"
14 hours ago
Jan Green replied to Rob Madden's discussion DOE Home Energy Score
"Agreed Sandy on all counts!   HES and HERS will be confusing to everyone that doesn't…"
15 hours ago
Steven Lefler replied to David Eakin's discussion A Growing American Problem In Search Of Valid Answers
"Modular Lifestyles has developed proven Net Zero factory built as a modular or his HUD code…"
15 hours ago
Joshua Fletcher posted a blog post

Are low-E glass windows good to install on desert homes?

Energy Efficient Windows That Lower Energy BillsThe technology used in windows continues to deliver…See More
15 hours ago
tedkidd commented on Home Energy Magazine's blog post Natural Gas is Becoming Less Attractive
"We are taking people off of natural gas. It is making sense financially, and has unpriced health,…"
16 hours ago

© 2016   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service