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: 12560

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

George Matthews replied to George Matthews's discussion Shortridge 8400 Flowhood for A/C airflow testing in the group Energy Auditing Equipment for Sale, Trade or to Purchase
"Here are the pics of the flowhood and airdata manometer"
yesterday
Sarah Holloway posted a photo
yesterday
Joe Urycki added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase
Thumbnail

TEC blower door and UEI combustion analyzer for sale

For sale is one used TEC Minneapolis blower door system: Includes model 3 fan with rings A and B,…See More
yesterday
John Nicholas replied to Kevin Emerson's discussion Studies re: radon mitigation and energy efficiency
"The Nay side is well represented with the links already posted. I presented a neutral side, with…"
yesterday
Ray Lehman replied to Kevin Emerson's discussion Studies re: radon mitigation and energy efficiency
"Hey John, Thanks for the information.  Very good empirical data. While I agree that running…"
Friday
John Nicholas replied to Kevin Emerson's discussion Studies re: radon mitigation and energy efficiency
"I have no links, just some anecdotal evidence. I had several Blower Door Tests done on my own home.…"
Friday
Chris Laumer-Giddens commented on Chris Laumer-Giddens's blog post Raising the BARrier in North Carolina Mountain Home, Air Tight Ceiling
"@Joe Nagan, We have found this technique to be WAY simpler and A LOT less labor than making a…"
Thursday
Judy Rachel replied to Blake Shurtz's discussion Testing spillage on induced draft furnace?
"I hope the attached picture is clear enough for you to see.  As the caption on the picture…"
Thursday

© 2016   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service