Over ventilated roof

Here’s a good example of an over ventilated roof. Shingle’s were just replaced and the roofer said the ridge needed to be ventilated, but why?

Existing home built in the 50s with soffit and gable end vents, no evidence in the attic of excessive moisture problems. Adding the ridge vent is causing negative pressure in the attic which in turn draws the snow though the gable end vent. What would you recommend?

over ventilated (2) (Small).JPG


-1101: A Crash Course in Roof Venting

Joseph Lstiburek
August 1, 2011
**Abstract: **

Understand when to vent your roof and when not to, and how to execute each approach successfully. Reprinted with permission from Fine Homebuilding, Aug/Sept 2011, pages 68-72.


Nice link Roy, Joe has published some great building science work.

I don’t understand why roofers always think they need to install ridge vents.

Take a look at this, same roof. They took the time to cut the roof open and install venting but left the chimney flashing in place where a cricket use to be and used peel and stick to flash it… Stupid.

peel and stick (3) (Small).JPG

I would recommend the roofer come back to correct the problems.

Buyer are requesting the sellers to have it fixed so I’m sure they will be back. Sellers are a nice older couple and knew nothing of it.
Pisses me off when I see stuff like this :twisted:

To block the gable vents, now that ridge vents are installed.

Something is not right here. I don’t see a screen on the inside of the gable vent. This would prevent snow and Bats from entering. There is no such thing as over venting. An attic should have as much ventilation possible, as being open to the outside. It is possible that the gable vent is the original one on the home and needs updating with a new one that will have a screen. There should be soffit venting also, if the home has soffits.
I recently rehabbed a 1946 home that had open gable vents without screens. I replaced them with new ones that had screens. So far, no problems.

Because it’s an upsell. Put it back on the roofer.

See item #4 http://www.airvent.com/index.php/ventilation-resources/literature-sales-tools/downloads/43-what-homeowners-should-know-about-attic-ventilation/file



Joe Lstiburek’s opinion on ventilation balancing is in here

Thanks Chuck, I understand ventilation, just don’t understand stupid roofers.

Sorry Bob I disagree and so do most of these web sites .
Please read a few Thanks |Roy


-1101: A Crash Course in Roof Venting

Joseph Lstiburek

I know. I was thinking they may be helpful to your clients may

My client was funny, he said it’s an f-ing new roof, the sellers better get the dam roofer back.

I’m thinking, OH OH ***** is gonna hit the fan :cool:

Hi Bob, screen is on the vent. This is a result of over ventilation and the result is snow is drawn through the vent and melts on the floor. This is an older home that just had a new roof installed and they added the ridge vent which is OK but they should have covered the gable end vents. Me personally I would have left it the way it was and just capped the roof. Why fix something that ain’t broke.

Check out the great links in this thread and learn about roof ventilation, you’ll be surprised.

Also, update your info so we know where your from, it will help understand your perspective.