Attic ventilation question.

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Old 06-23-16, 04:39 PM
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Attic ventilation question.

According to this site, Calculate Your Roof Ventilation | Owens Corning™ Roofing I need to have more vents than I do. Can I just be lazy for now and take about half of the fins off each soffit vent to help with air flow for now? Just looking for a quick possible fix here in Texas. Attic space is around 2000 square feet.
 
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Old 06-23-16, 05:30 PM
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I'm not sure what you mean by fins on the soffit vents. You need sufficient soffit venting and attic venting. The idea is that, since hot air rises, cool outside air is drawn in via the soffits, rises, and gets expelled via the roof vents (either ridge vent or individual vents). You need enough ventilation at both the soffits and the roof. If one is too small, you can't compensate for it by making the other larger.
 
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Old 06-23-16, 06:38 PM
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I mean.

Each vent has several rows of metal bars that are spaced pretty close together. If i brake some of them off it could allow more air to flow through. Kind of like the high flow vents i that have huge openings for air to get out that i bought for the a/c system inside the house. They seem to let about 50-100 cfm more of air out each vent at times.

Only example I can find.
TruAire 14 in. x 8 in. 3 Way Wall/Ceiling Register-H103M 14X08 - The Home Depot low flow

Breaking off half the slats would help airflow imo.
 
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Old 06-23-16, 06:46 PM
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OK, now I know what you mean. While breaking off some of the fins would increase the allowable airflow through the soffit vents, it won't really help the attic ventilation if you have insufficient airflow through the attic vents. As I mentioned previously, the soffit vents are the air "inlet" and the roof vents are the air "outlet". They need to be reasonably matched in airflow capacity. If you have reason to believe that your soffit vents are not allowing sufficient airflow, then "opening them up" will help, but only to the extent that the roof vents can exhaust the additional airflow.
 
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Old 06-23-16, 06:59 PM
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Last person working on house went overboard i think.. 8 whirlybirlds for 2000 square foot house.
 
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Old 06-24-16, 05:37 AM
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OK, so it sounds like you have plenty of attic ventilation. I see no problem with opening the soffit vents. You may want to make sure that nothing (e.g. birds) can get in through the soffit openings.
 
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Old 06-24-16, 08:05 AM
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The calculator you linked to is using the 1/300 assumption, but that requires a vapor barrier and a well air sealed ceiling/attic floor. How old is your house and have you done any attic air sealing. If not, then your total vent area may have to double.

How many soffit vents of what size do you currently have?

But don't panic, there is a lot of flexibility in the guidelines, so tell us what you have and we can judge is removing vanes will help at all.

Bud
 
 

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