Although not part of the living or occupied area, a crawlspace is one of the more important areas of a building, yet one of the most neglected and misunderstood areas. Actually, it has a profound impact on the air quality in the occupied area of the building because of the stack effect. As air warms within the building envelope, it moves upward; that is the stack effect. The air within a crawlspace travels upward, infiltrating the living area through the ductwork, gaps in the flooring, through and around holes from wiring, conduit, and plumbing. If there are indoor air quality issues in the crawlspace, they will impact the living areas in the floor above. Up to 40% of the air on the first floor in a home originates from the crawl space or basement.
Crawlspace encapsulation is a term referring to the process of eliminating unhealthy conditions by sealing and insulating the entire crawlspace for improved energy efficiency and indoor air quality throughout the home. Other terms sometimes used to describe the crawlspace encapsulation are closed crawlspace, sealed crawlspace, and conditioned crawlspaces.
The method entirely isolates the crawl space from the ground and outside air by lining the foundation walls and crawlspace floor with an extra-heavy reinforced vapor barrier and maybe installing either a conditioning system or a dehumidifier. By sealing the crawlspace with a combination of poly wrap and insulation, air infiltration and moisture infiltration are reduced, ensuring a healthier and safer home with less risk of mold and reduced energy bills.
The reason the vented crawl spaces have higher humidity is actually pretty simple. Warmer air can hold more moisture, so in the summertime, the outdoor air can bring a lot of extra water vapor with it when it comes into a crawl space through the vents. When that warm, humid air comes into the crawlspace and cools off, the relative humidity can go even higher.
The process of crawlspace encapsulation begins by surveying the house with energy diagnostic tools, including an infrared thermal imaging camera and a blower door to identify rates of air leakage and areas where insulation is missing or compromised, and where cracks and gaps in the building envelope are leading to air leakage. The next step is to address these areas using air sealing materials which may include a combination of insulation, caulk, weather-stripping, poly wrap, spray foam, and any other appropriate materials. At the end of the project, your crawlspace is brought inside the building envelope, which leads to a variety of benefits such as:
A more comfortable home: in summer the house won’t be muggy; during winter floors won’t be cold.
Breathe easier: highly improved indoor air quality.
Reduce the chances of costly floor repairs. Moisture rots wood and causes hardwood floors to buckle.
No more critters: A damp and humid crawl space is just inviting for any bug, such as termites.
An encapsulated crawl space is an attractive selling feature. Potential buyers comparing two similar houses will find the one with an encapsulated crawl space more appealing.
Reduced moisture problems: Water and moisture are equally devastating to your home. Water keeps a moisture problem alive as well as delivering a punishing blow to your foundation. Even if you get a standing water problem under control you may not be done with the moisture problem. When the temperature of the air is warmer than the temperature of the surfaces in your crawl space you have condensation, which means trouble for your home.
Reduced risk of mold, mildew and fungus problems: Dry Rot is a fungus and so is Mold and Mildew. All three are living plants and need food, water, and carbon dioxide, among other things, to live. The food fungus eat is our house. So its food source can’t be removed, either the carbon dioxide. Therefore, to prevent the fungus temperature and moisture must be controlled.
Reduced cooling costs: Water runs out of your air conditioner when it is running; this is a byproduct of cooling the air before it goes into your home. The cooling coils that cool the air also cause condensation by drawing the moisture out of the air. The warm moisture in the air, when it comes in contact with the cold coils, warms the cooling coils making your air conditioner work harder to keep the coils cold. This problem with the moisture will make your air conditioner run longer. The more moisture, the harder it has to work. The harder your air conditioner has to work the more expensive it is to cool your home. Eliminate the moisture, eliminate this cycle.
Reduced energy bills: Crawl space encapsulation can reduce energy bills by up to 20%.
Make your heating & cooling equipment and ducts last longer: An air handler and ducts in a vented crawlspace will not last as long as equipment in a conditioned crawlspace.
Qualify for rebates and tax incentives. Some utilities offer rebates. The federal government has tax incentives for home performance improvements. Some state and local governments offer incentives as well.
Crawlspace encapsulation is becoming a very popular home improvement. The crawlspace is no longer neglected and instead is treated as a part of the home like a basement. By transforming your crawlspace into an encapsulated crawlspace you are creating a space you can control. The goal is to completely eliminate outside air and ground moisture from entering the building envelope. The list of benefits, as you see, goes far beyond just saving on the energy bills and cleaner air.