What Causes Condensation in Crawlspaces and Basements?

In many parts of the country during the spring, summer and fall months, warm, moist air enters the vented crawlspace from the outside and condenses on the cooler surfaces of the walls, floor and ductwork. These cooler surfaces are created within the crawlspace or basement by it being partially or entirely underground and shaded – much like a cave!

DP_condensation_arrows• If the Dew Point (DP) temperature is ABOVE the surface temperature,
condensation will occur.
• If the Dew Point (DP) temperature is BELOW the surface temperature,
there will be no condensation.

SF_condensation_infographCondensation Contributes To:

  • High Humidity
  • Pest Infestations
  • Poor Indoor Air Quality
  • Mold Growth
  • Musty Odors
  • Damage to Property

How do I prevent condensation?

Santa_Fe_Advance2-1Santa Fe offers a full line of dehumidifiers to help prevent condensation in these spaces. Several of the units feature dual exhaust to provide optimal airflow. This airflow helps prevent spot condensate, and in combination with the dehumidification, protects crawlspaces and basements.

Crawlspace Encapsulation Overview


Homes that are properly encapsulated, continuously monitored and treated with a Santa Fe dehumidifier are protected from both the humid outside air and the ground’s natural moisture. An added bonus is that this strategy minimizes fungi and mildew growth, guaranteeing a more structurally sound and healthier home.
Crawlspace Facts
  • According to a study by Advanced Energy, homeowners can expect to reduce their energy bills by 15-18% by sealing off their crawlspace. They also determined that homes with vented crawlspaces were 19 times more likely to experience relative humidity levels in excess of 70% than homes with encapsulated crawlspaces.
  • As much as 50% of the air in a home’s living space originates from the crawlspace.
  • Most pests are attracted to moist environments; as a result, moisture control is an important part of any fully integrated pest management system.


Moisture is the Mother of Most Biological Evils

There are many sources that can cause moisture in your home, including:

  • Plumbing, flashing, and roof leaks
  • Damp basements and crawl spaces
  • Cooking, showering, and indoor line drying of clothes
  • Humidifiers
  • Improperly vented combustion appliances and clothes dryers
  • Flooding and sewer backups
  • Poorly maintained gutters, downspouts and drains
  • Landscaping and plants that block crawl space vents and drainage systems

stack effect imagesWhile some signs of excess moisture maybe obvious, like condensation on windows, often times they are hidden in the crawl spaces and basements of the home.  This polluted air below the house will eventually move to the rest of the house, often times carrying odors, contributing to poor indoor air quality and causing uncomfortably high humidity levels.  Studies show that as much as 50 percent of the air in a home comes from these below-grade areas.

Moisture is also the fuel that feeds the fire for mold.  Mold needs water to grow – without it mold cannot grow. Mold also needs a food source and a temperature between 40 degrees and 100 degrees F.

Effects of Moisture on Your Home

wood-rotExcess moisture in your basement or crawl space can cause mold to grow. Mold can grow in or on almost anything in your home, including furniture, carpet, wood, dry wall, and insulation. Too much moisture can also cause wood to buckle, split and even rot, which may weaken the structure of your home. It can even cause peeling, chipping or cracking of paint.

Effects of Moisture on Your Health

dustmitesMold, bacteria, cockroaches, and dust mites have been linked to triggering allergies and asthma attacks and may even cause children who do not have allergies or asthma to develop either condition. Exposure can cause coughing, sneezing, wheezing, upper respiratory irritation and asthma symptoms.

The Environmental Protection Agency’s offers A Brief Guide to Mold, Moisture, and Your Home.

Santa Fe Impact – Most Energy Efficient Dehumidifier in the World

The Santa Fe Impact is specifically designed to dramatically impact the moisture in your crawlspace/basement, your energy bills and the environment.

It is the most energy efficient dehumidifier on the market – exceeding Energy Star® standards by 50 percent. The Santa Fe Impact removes up to 105 pints of water a day while using an unprecedented 4.9 amps (8.8 pints per Kilowatt hour). It effectively dehumidifies up to 2,500 square feet and is the ideal free-standing dehumidifier for meeting aggressive energy use targets. The unit is engineered for extreme quiet operation and is optimized for low heat load. Optional condensate pump and ducting kits provide the installation flexibility necessary for the most challenging applications.

How to Dry-Out After the Flood Waters Recede

Knowing how to safely and effectively dry your home and belongings after a hurricane is imperative in the prevention of costly and damaging mold growth, especially in low-lying areas such as basements and basements.

It is important to dry out the water-damaged areas as quickly as possible. Relative humidity levels rising above 60 percent stimulate the growth of mold, mildew, bacteria and other biological allergens, which can potentially create dangerous living conditions.

The first step is to remove all of the remaining floodwater as quickly as possible either by using sump pumps or calling a local restoration professional. After you are sure the basement is safe to enter, follow these steps provided by the Center of Disease Control and Prevention:

  • Remove and discard items that cannot be washed and disinfected (such as, mattresses, carpeting, carpet padding, rugs, upholstered furniture, cosmetics, stuffed animals, baby toys, pillows, foam-rubber items, books, wall coverings, and most paper products).
  • Remove and discard drywall and insulation that has been contaminated with sewage or flood waters.
  • Thoroughly clean all hard surfaces (such as flooring, concrete, molding, wood and metal furniture, countertops, appliances, sinks, and other plumbing fixtures) with hot water and laundry or dish detergent.
  • Help the drying process by using fans, air conditioning units, and dehumidifiers.

Drying rates are greatly improved by lowering relative humidity, adding heat and increasing air movement; all functions of a high powered dehumidifier. Experts recommend using dehumidifiers with a regenerative heat exchanger and high capacity fan, like the units offered by Santa Fe. These features are necessary for fast and effective drying.

Not All Dehumidifiers are Created Equal
Santa Fe dehumidifiers feature a large moisture removal coil, regenerative heat exchanger and high-capacity fan, which allow the units to remove 2-3 times more moisture per kilowatt of electricity than a conventional dehumidifier. In addition, Santa-Fe dehumidifiers allow for high efficiency air filtration. These freestanding residential units are built with the same components as the company’s commercial units and as a result are able to remove up to four times more water than the units available at home improvement stores.

Santa Fe high capacity dehumidifiers are the most energy efficient on the market and are designed to effectively and quickly remove excess moisture due to flooding. The units can help maintain the structural integrity of your home, minimize mold growth, and improve the indoor air quality of the overall home by removing odor-causing moisture.

If you are unsure about how to clean an item you may wish to consult a specialist. Specialists in furniture repair, restoration, painting, art restoration, carpet and rug cleaning, and water damage are commonly listed in phone books. Be sure to ask for and check references and look for specialists who are affiliated with professional organizations.

Santa Fe Compact2 Dehumidifier – Little Design that Delivers a Lot of Punch

The Santa Fe Compact2 was specifically designed to fit into tight, low-clearance spaces, such as crawlspaces.  But don’t let its’ small design fool you – the unit removes up to 70 pints of water a day and can treat spaces up to 1,800 square feet.  No other conventional dehumidifier can perform as efficiently and effectively in crawlspaces and basements as the Santa Fe Compact2 Dehumidifier.

Crawlspace Before and After Pictures

Sealing off a crawlspace and removing excess moisture will help control pests, improve overall indoor air quality, protect your home against structural damage caused
by moisture, and reduce your energy bills.  There are several options when it comes to treating your crawlspace based on what region of the country you live in and the local building codes.

The crawlspace featured in these photos is in Charlotte, South Carolina and was encapsulated.  Meaning all opening were sealed, including vents and doors leading from the exterior, also the foundation and the floor were lined with a premium grade vapor barrier to prevent moisture from seeping into the crawlspace.


Inferior vapor barrier

Opossum feces and urine


Proper installation of a premium grade vapor barrier is essential to controlling moisture, and as a result, minimizes the pests and mold that thrive in a damp crawlspace.

Also installed was a Santa-Fe Dehumidifier that is specifically designed to operate in crawlspaces.

The Santa Fe Advance Dehumidifier will help reduce excess humidity, making the crawlspace inhospitable for fungi, dust mites, wood destroying insects, and other pests.

What are the Recommended Relative Humidity (RH) Levels for my Basement and Crawlspace?

Studies have shown that as much as 50% of the air in a home comes up from the basement or crawlspace.  This air is often higher in moisture content, and carries with it various allergens and musty odors. The Environmental Protection Agency, American Lung Association, and American Medical Association all recommend maintaining RH in the 30% – 50% range.

When conditions linger above 60% RH for extended periods of time; mold, mildew, and bacteria grow.

A commercial grade Santa Fe high efficiency dehumidifier is designed to consistently maintain 50% or less RH in crawlspaces and basements.

Potential Issues for Homes with Crawlspaces

Nearly 19 million homes in the United States have crawlspaces. The trouble with crawlspace construction is it can potentially affect the living space above it and have more wood rot problems than other types of construction.

It has been proven that warm, humid outdoor air brought into the crawlspace through foundation vents in the summer can lead to increased moisture levels in the crawlspace and eventually into the home. The air introduced through the vents into the crawlspace does not always move side to side but instead will move upwards, which is called the “Stack Effect.” This Stack Effect draws air inward from every crawlspace vent and up into the living space, resulting in increased humidity levels and musty smells throughout the entire home.

Wood Rot

Wood rot only occurs when the moisture content is above the fiber saturation point, about 27% to 28% wood moisture content. In order to keep this in perspective, consider the following:

  • Fresh-cut wood is typically around 200% moisture
  • Kiln-dried wood has seven to 10% wood moisture content
  • Air-dried wood has a typical moisture content of 19%, but that varies with the relative humidity (RH).

The 28% wood moisture content necessary for rot to occur doesn’t come about from just high humidity. Water has to make contact with the wood before the wood rots. Any time the relative humidity is over 70%, you can get spot condensate because temperatures vary throughout a crawlspace.

A solution to this problem is the new Santa Fe Force dehumidifier that features dual exhaust and is specifically designed to provide the optimal amount of airflow in crawlspaces and basements. This airflow helps prevents spot condensate, and in combination with the dehumidification, protects the crawlspace and living space.