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Odom Designs builds new homes along the Grand Strand that are on pilings or raised concrete slabs to prevent coastal flooding. First, soil samples are taken from the build site. The samples are sent to a lab for analysis before the final foundation type is selected. These building methods also eliminate the need for crawl space ventilation entirely.

But what about the crawlspace in your current home? To vent or encapsulate?

Why do houses have a crawl space?

The original idea supporting crawl space vents was to allow air to circulate under the home. The fresh air would combat the moisture under the home. Most people close their crawl space vents during the fall to keep their homes warmer. Then, they reopen them in the summer to allow warm air to dry the crawl space. This is a poor option in humid climates like Myrtle Beach. Our high humidity levels may quickly cause mold growth in the crawl space. It can also affect your HVAC system if it is located under the house.

In recent years, we’ve learned that it is most efficient to encapsulate your crawl space. The dirt beneath the house is covered with a plastic membrane or concrete. This barrier protects the crawl space from ground moisture accumulating under the home. The vapor barrier extends up the sides of the foundation walls and is sealed at the floor joist.

How do you reduce moisture levels low in the crawl space?

The most common and cost-effective way to add dry air to the space is with the HVAC system. A new duct line will vent fresh air under your house. This method is dependent on the location and size of your HVAC unit. If your unit is already at capacity, this method is not an option. It also requires the system to run regularly. Unfortunately, it is still possible that humidity could get too high in the crawlspace during mild times of the year when the HVAC system doesn’t operate often.

Another option is to add a small exhaust fan to your crawl space. Per the IRC, that calls for:

Continuously operated mechanical exhaust ventilation at a rate equal to 1 cubic foot per minute (0.47 L/s) for each 50 square feet (4.7m2) of crawlspace floor area, including an air pathway to the common area (such as a duct or transfer grille), and perimeter walls insulated.

That equates to a 40 CFM fan for a 2,000 square foot home. The downside to this option is that you can’t be 100% sure where that makeup air is coming from. While it should be drawing from the inside of your home, it could pull air from a poorly sealed perimeter wall and add moisture to the area. Many believe that using the HVAC system to add air is a better option.

The best, and coincidently, most expensive option, is to add a dehumidifier to the crawl space. This method ensures that your encapsulated crawl space will stay dry. This method is not without its own drawbacks. If the drain fails, you could have a large amount of water in the crawl space to deal with. Furthermore, dehumidifiers require regular maintenance.

Choosing the right contractor.

Whatever method you choose, seek out a licensed and insured contractor to complete the work. Encapsulating and dehumidifying a crawl space is an important task. If done improperly, you could soon have expensive mold and rot problems in your home. If you’d like to know more about crawl space ventilation or home construction, contact us today.