Should I Close My Foundation Vents or Should I Keep Them Opened?

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Should I Close My Foundation Vents or Should I Keep Them Opened?

Should I Close My Foundation Vents or Should I Keep Them Opened?
Aug 01, 2019

We get asked this question a lot.

The answer?

It depends…


Foundation vents are base vents located in the crawl space of your home. Typically, they’re built open, but they can be closed using custom blocks should a homeowner want to close them.

Why are foundation vents designed open, and if they are designed open why would anyone want to close them?

Open Foundation Vents

The idea behind building “open” vents is simple.

The foundation of your house is made of soil, and soil contains moisture. This moisture can leach into your crawl space from the soil and eventually throughout your house. Moisture inside a house is bad: it can weaken cement supports, rot wood and cause mold growth. Therefore, it must be displaced. That’s where foundation vents help. When open, they allow moisture in the crawlspace to escape back into free air and thus prevent its buildup.

Open Foundations Vents in Winter

In winter, however, when you have your home HVAC on the heating mode, keeping your foundation vents opened can be a problem.

The heat produced by your HVAC unit will eventually travel to your crawl space. If your foundation vents are open, the hot air will escape through them. This will create an energy drain on your house and significantly increase your energy bill.

Surely, you don’t want to be paying a high energy bill?

To Close or Not to Close

So, to summarize:

You should keep your foundation vents open in summer to allow for crawl space ventilation, and you should block them up in winter to keep your house warm and cozy.

It’s must be mentioned here, that in some climates, especially in the South, it’s better to keep your foundation vents closed all the time. That’s because the humidity in these areas is usually high, and as such if your foundation vents are open, it can invite the warmer, more humid air into your crawl space, which isn’t really what you want.

How would I then ventilate my crawl space, you ask?

You can use a dehumidifier or an crawl space exhaust fan to provide ventilation in your closed crawl space.

 Foundation Vents

Here, at Crawl Space Door Store, we sell high performance crawl space dehumidifiers and crawl space ventilation solutions at affordable prices. Visit our online store to learn more.

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Why buy a crawl space door, flood vent,
air vent, or portable fan system?

  • Save Money

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    Use our crawl space air vents and doors to ventilate your crawl space with natural air flow or forced air with our energy efficient exhaust and portable fans.

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    Save The Environment

    Reducing the moisture in your crawl space reduces mold that releases airborne mold spores into the environment.

  • Green Crawl Space

    Green Crawl Space

    Ventilate your crawl space with natural air flow with our crawl space air vents, louvers, and exhaust fans.

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