# Humidity after new roof & ridge vents added



## justahomeowner (8 mo ago)

Homeowner here who knows nothing about roofing. I just had a new roof put on and they added ridge vents. The roof is steep with a tall attic and currently has continuous soffit vents and 3 gable vents. I questioned the addition of the ridge vents, however all 3 companies that gave us quotes said we needed them. Ridge vents were added at each peak (3 or 4 in total), including over the garage where this is no attic. 

Since the new roof was put on and the ridge vents added 3 weeks ago, we've had problems with outdoor odors coming in and high humidity in the house. It feels like outdoor air is being pulled into the house. I live in VA where it's humid this time of year. It's humid inside on both hot and cool days (we've had temps in the 90's and 60's recently so not an issue only when hot). I had our 2 HVAC systems serviced to see if that was the problem and they are running fine.

Thoughts on if the ridge vents could be causing the humidity problems? The HVAC guy said he's never seen holes cut so big for the ridge vents. He admits to not being a roof/ventilation expert, but said he's been in a lot of attics and never seen holes cut so big. I asked the roofer who did the work to come look at the problem and he's coming tomorrow to do an inspection, however he told me the high humidity would have nothing to do with the ridge vents. 

Note that we didn't have any issues with humidity, ventilation or anything else with the old roof. I thought ridge vents and gable vents weren't both supposed to be used together? That's my guess on the problem, but wanted to see if anyone had any other advice or tips for me to speak with the roofer about?

Thank you!


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## andy (Oct 30, 2011)

Ridge vents should be used in conjunction with continuous soffit vents and not be used with gable vents. Gable vents are a standalone system.


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## Polaskidays (5 mo ago)

I’m not a building or roofing professional but I’ve been doing research on the topic for my own issue and Dr. Joe Lstiburek is a expert in the building science field. He mentions In the video that accompanies the first article that if you have your upper exhaust vents capable of pulling more air volume than your soffit vents can supply, the conditioned air from inside the house will be drawn up through any leaks in your ceiling plane to help make equilibrium. I believe he says if anything you want slightly more soffit supply venting by area than exhaust venting to keep the attic slightly pressurized so you’re not drawing out conditioned air from the house which is then replaced with unconditioned outside air.
Not sure how the gable vents might change the equation though.









Lstiburek’s Rules for Venting Roofs - GreenBuildingAdvisor


Building Science Fundamentals: Roof, Part 1: Ventilation By Dr. Joseph Lstiburek Dr. Joseph Lstiburek talks about the not-so-controversial ways to maximize the efficiency and airflow of your roof and attic. Video Transcript: There’s been so much stuff said about roofs that you sometimes lose...




www.greenbuildingadvisor.com










PA-1101: A Crash Course in Roof Venting


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.




www.buildingscience.com


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## andy (Oct 30, 2011)

Polaskidays said:


> I’m not a building or roofing professional but I’ve been doing research on the topic for my own issue and Dr. Joe Lstiburek is a expert in the building science field. He mentions In the video that accompanies the first article that if you have your upper exhaust vents capable of pulling more air volume than your soffit vents can supply, the conditioned air from inside the house will be drawn up through any leaks in your ceiling plane to help make equilibrium. I believe he says if anything you want slightly more soffit supply venting by area than exhaust venting to keep the attic slightly pressurized so you’re not drawing out conditioned air from the house which is then replaced with unconditioned outside air.
> Not sure how the gable vents might change the equation though.
> 
> 
> ...


Gable with ridge vents end up circulate the air from outside the gable vent into the attic and out the nearest ridge vent creating a small area of air circulation a couple feet from the gable wall. The same air pretty much does a circle in that space.


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