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?
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.
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.
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.