For years the waterproofing industry endorsed venting a crawlspace as the best practice but research is showing that it may not be the best way. We are taking a hard look at sealed crawlspaces vs dirt floor crawlspaces and the science behind them. Learn the pros and cons of each and why a sealed crawlspace may be the best solution for your home.
Dirt Floor Crawlspaces – The Traditional Method
The traditional method of industry-standard venting of dirt floor crawlspaces was thought to be the best prevention of condensation and the growth of mold, mildew, and bacteria. Now science is finding that may not be the best solution. In fact, venting dirt floor crawlspaces is shown to be the inferior method when it comes to optimum humidity levels, energy efficiency, and preventing mold, mildew, and fungus growth.
Sealed Crawlspaces
With more and more homes turning to sealed crawlspaces through crawlspace encapsulation, the data is showing it is the most method to reduce humidity and condensation, prevent musty odors, protect your floor joists, pipes, and HVAC system, and improve energy efficiency in the home. Sealing out all outside air and creating a sealed system under your home is the best way to control conditions with optimal results.

Condensation and Humidity with Dirt Floor Crawlspaces vs Sealed Crawlspaces
During the warmer months of spring and summer, warm air from outside flows through the vents and comes in contact with the cool dirt floor. When warm, humid air and cold ground meet, the temperature of the air lowers and the water vapor in the air condenses. This means that condensation is going to happen. Where do these water droplets land? The dirt floor, floor joists, pipes and electrical, and anywhere and everywhere else in your crawlspace.
Condensation in your crawlspace is never a good thing. It can lead to the degradation of your floor joists, (which affects floors, windows, and doors above), corrosion of pipes and any home systems that are housed in your crawlspace, and encourages mold, mildew, and fungi growth in your crawlspace.
A 2005 study by Advanced Energy in North Carolina found that homes with sealed crawlspaces were much drier than those with dirt crawlspaces and had an average humidity level below 60%. A similar 2009 study in Baton Rouge, LA found that humidity levels in sealed crawlspaces hovered at 60% (an optimum level) while dirt floor crawlspace humidity levels were at 80%.
When a crawlspace is sealed, there is no chance for the warmer air to meet the cool ground and condense creating a locked air space. The temperature varies only slightly making the chances of damage from condensation negligible. The humidity level is controlled at healthy levels due to the sealing of the space under your home and only varies slightly over the seasons.
Energy Efficiency with Dirt Floor Crawlspaces vs Sealed Crawlspaces
During the cooler months of autumn and winter, venting allows the cooler air from outside in and since 40% of the air inside your home comes from your crawlspace, that cooler air steals heat from indoors. Heat that you are paying for with your energy bill. A similar air exchange happens in the warmer months as the hot air seeps into your cooler air-conditioned air upstairs. This is known as the chimney effect.
Again, the sealed crawlspace prevents this air exchange from ever happening ensuring that your energy efficiency is at its peak. Studies show that sealing your crawlspace can save you 15% or more on your energy bill each month! When your crawlspace is sealed, you can rest assured that you are not paying for conditioned air that is going to waste!
Air Quality in Sealed Crawlspaces is Best
When crawlspaces are sealed, the humidity level is controlled and therefore condensation is also controlled. Mold, mildew, and fungi thrive in dark, warm, and moist environments. Dirt crawlspaces, even when vented, can become a breeding ground for these harmful growths. As mentioned above, 40% of the air inside your home comes from the crawl space. When you or your family are exposed to this unclean air, it can be detrimental to your health. Effects of exposure to mold, mildew, and fungi include headaches, fatigue, sinus problems, coughing, sore throats, and irritated eyes.
Sealed crawlspaces do not allow for the growth of mildew, mold, fungi, or any other bacteria. Any musty or bad smells are eliminated. The air is the best quality and therefore you are breathing clean air on a daily basis. Our homes are our havens so it only makes sense that we prioritize our air quality and health in our own homes.
Ready to Seal Your Crawlspace?
Sealed crawlspaces dramatically outperform traditional dirt floor crawlspaces. If you are ready to lower your energy bills, protect your home’s foundation, and improve the quality of the air you breathe through crawlspace encapsulation, contact Aqua-Guard Waterproofing. Our team of professionals can get the job done quickly and get the job done right. We off a “Life of the Structure” guarantee on all of our work also. This means you can trust that we stand behind the quality of our work. Contact us today for a free estimate.