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View Full Version : soffit vents big enough?



Kerry Adams
05-10-2009, 12:55 PM
Good Afternoon,

I am getting ready to paint exterior. The soffit vents looked smashed, so I take one off to replace and notice that the hole that was cut is quite small-about 2 and a half by eight.Should I make the holes larger?

The house is 15 years old and in South Carolina. I have roof vents and the roof is in good shape. Should I leave well enough alone?

Thanks,
Kerry

Don Bullock
05-10-2009, 1:20 PM
Kerry, check your local building code. Where I live, for example, the vents are supposed to be very small due to the possibility of fires in the area. Most people don't realize that many homes that are lost in wildfires here in Southern California are due to the fire gaining access to the attic area through the soffit vents.

David G Baker
05-10-2009, 2:51 PM
Kerry,
In my opinion the vents are large enough but you need to make sure that the path is clear in your attic to allow the air to pass freely to the attic vents.
I agree with Don about checking with your local code and the number of houses lost due to those vents by wild fires. I covered the California Berkeley Hills fire and listened in on a lot of the press conferences about preventative measures required to help prevent destruction of homes by wild fires. Several homes were spared due to real tile roof and soffits constructed from fire resistant materials. Not sure what was said about the soffit vents. Around 3000 structures were lost in the Berkeley Hills fire.

Brian Effinger
05-10-2009, 11:12 PM
Kerry, I agree with Don & David. Most likely you have enough ventilation, but may be a good idea to check with your local building inspector - he'll know what the local code is.

The IBC residential states: "The total net free ventilation area shall not be less than 1 to 150 of the area of the space being ventilated". This basically means that if your attic space is 100 square feet, then you need 1 square foot of ventilation. There are ways to reduce this ratio, but for here we'll just stick with 1:150. So, if your attic isn't getting excessively hot, and the roof looks good and has no curling shingles, then you're probably ok.