“My dad is a builder, and he says the crawlspace vents have to stay open…the space needs to breathe.”

We hear this almost every week in Atlanta during our crawlspace inspections. One of the first questions I’ll ask a customer is “Do you know why your home has those foundation vents?” Most people will giggle and say they have no clue why they are there, what they do, or whether to open or close them. It’s an honest answer.

Let’s talk a bit about whether or not you should open or close those crawlspace vents.

First of all, the vents are present because at the time your home was built, the code required them to provide ventilation to the crawlspace. That is exactly what they do . . . but is this a good thing or not? To better understand it, consider that there is dry air and there is wet air. Of course, we want dry air under our house. In Georgia (and the entire Southeast), predominantly we have wet or humid air outside most of the year. By leaving your vents open, you’re constantly introducing wet air under your home. Moreover, this is done in the name of “drying out the crawlspace.”

When you introduce wet, humid air into your crawlspace, you’re actually making the problem worse.


Wet air makes things more wet, not less wet. We can get into Dew Point Temperature, Relative Humidity, and other things, but the easy way to understand this is pretty basic: if you introduce wet air into the crawlspace, you’ll create a damp crawlspace. Damp crawlspaces breed mold, create unpleasant odors, and provide a home for insects. . . all of the things you’re trying to avoid, and most likely the very issue you’re trying to solve.

In short, if you’re trying to create a clean and dry space under the house, you’ve got to keep those vents closed!

It’s part of what we call an Encapsulated Crawlspace. If you find yourself stumped about why your house has those vents in the first place, the most direct answer is the code was written by some well-intentioned folks who just didn’t understand what they were doing. But don’t worry, we can fix it!

You’ll also have to be on guard against the Pest Control Industry in this category. Ask around, and you’ll find the pest guy wanting to sell you more vents so there will be more ventilation under the house. He’s right in that there will be more ventilation, but with it will come more wetness.

Give ACS a call today for a no-nonsense scientific approach toward solving your moisture issue.

Contact ACS

Please Call Us Anytime if You Have a Question About Your Basement, Crawlspace or Foundation

Call Us

(678) 871-7890