Should I Open Or Close The Air Register For Hvac In Crawl Space

Crawl space vents are a common fixture in many Virginia Beach, VA, homes. For many years, they've been fronted as a way of promoting air circulation in the crawl space. Homeowners would open their vents to allow fresh outside air to circulate the crawl space and cool their homes.

Local codes and conventional wisdom requires crawl spaces to be ventilated from the outside to control moisture buildup and reduce damage within the space. But are crawl space vents really a good idea? We shall find answers to this question so you can decide what's best for you.

What Do Local Codes Say?

First of all, building codes say leaving the vents open is good. But they also say you could close them. So, they're giving the homeowner or builders a choice whether to create an encapsulated system or an open system. However, in both cases, you still have to fulfill or meet certain conditions. We strongly recommend you close the vents as there's no way to control humidity when the crawl space is open.

Are Crawl Space Vents Effective?

Imagine you're living in a home, where the outside temperatures can hit 90 degrees. You have your HVAC running and it's brought down the internal temperature to 65 degrees. Then you open the windows and warmer air rushes in. What happens? Warmer air will instigate condensation while raising the internal temperatures. That's exactly what happens you have a vented crawl space.

Although crawl space vents are mandatory in many areas and the intention behind them good, the logic behind vented crawl spaces is faulty. In fact, venting does the exact opposite. Your home would be safer and healthier if you cover the vents.

Sealing and controlling ventilation is the way to go. With this approach, you're still ventilating but controlling the humidity with a dehumidifier.

Disadvantages of an Open Crawl Space

Various studies have shown that ventilated crawl spaces do more harm than good to your home. Vents let in excess moisture during humid and wet weather conditions. And this can raise humidity levels and foster various problems. Even if you install vapor barriers, they won't keep the crawl space dry enough to stop mold growth.

Your biggest worry should be condensation, a phenomenon that occurs when warm outside air comes into contact with cooler crawl space air. Condensation can trigger mold growth, which can range from light spotting to heavy staining as well as wood rot, decay, and rust. Over time, condensation can cause water puddles to form on the crawl space floor.

The passive intrusion of humid air via vents can also contribute to a weaker support structure. Decaying and rotting wood won't be able to support the home above. This can lead to potentially expensive repairs.

More than 50% of the indoor air comes from the crawl space. A crawl space measuring 1,000 square feet can produce up to 10 gallons of moisture in a day, rising into your home and causing a number of issues besides forcing your HVAC to work even harder.

Another concern is that venting can affect the quality of indoor air in the home. Upward moving air can carry with it mold spores, dust, pollutants, and allergens. All these can make the indoor air unbreathable. Anyone with breathing problems like asthma will be affected greatly. And that could mean more hospital visits and coughing.

Not only does outside air bump up moisture levels, but it also increases home heating costs. Upward moving air creates a stack effect. You'll find yourself running the air conditioner for longer to harmonize the conditions in your living space and the crawl space.

Close Vents for a Healthier Home

U.S. homes with closed crawl spaces outperform their vented crawl counterparts with regards to structural health, air quality, mold-resistance, and energy efficiency. Closed crawl spaces stay significantly drier than the wall vented crawl spaces with relative humidity levels staying below 60% for most of the hot and humid summer months.

Want to keep crawl space moisture in check and create a healthy space? Seal all the vents and condition your crawl space. JES Foundation Repair professionals are experts in crawl space encapsulation and dehumidification. They can suggest a long-term and effective solution to control crawl space moisture while providing fresh air exchange. Kick start your project with a free crawl space inspection and quote.

Free Homeowner's Guide to Crawl Space Repair

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