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.

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.

Dust Mites Linked to 80 Percent of Asthma & Hay Fever

dustmitesResearch out of the UK finds common household dust mites may be a factor in as many as 80 percent of asthmas, hay fevers and other allergic ailments. Along with respiratory symptoms, high levels of dust mite allergens have also been correlated with atopic dermatitis (AD), characterized by itchy, irritated skin.

Dust mite allergens are considered one of the most potent allergens in household dust. Their body parts and fecal excreta are initially 10 to 50 mm in diameter but break down into smaller fragments that become airborne when dust is disturbed. According to one study, more than half the weight of mite allergens within a home was found to be less than 5 mm in length. Because of their small size, fecal material is the primary health concern due to the fact that they can be inhaled into the lower airways of the lungs.

Dust mites are microscopic hardy creatures that live and multiply easily in warm, humid places. They thrive at temperatures at or above 70 degrees with a relative humidity of 75 percent to 80 percent. They die when the humidity falls below 50 percent. According to the American Academy of Allergy, Asthma and Immunology (AAAAI), to reduce dust mites, it is important to keep humidity below 50 percent throughout the home.

It has been proven that there is a dramatic reduction in dust mite population when humidity is controlled in the home, but many people struggle with finding a dehumidifier that can accomplish this.  The most effective and efficient solution is to use a quality, high capacity dehumidifier that controls humidity levels throughout the entire home.

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. All units come with at least a MERV 8 filter, and most come standard with MERV 11 filtration capabilities. Santa Fe 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. All Santa Fe dehumidifiers are ENERGY STAR® rated.

AAAAI also recommends these solutions to control dust mites:

  • Removing wall-to-wall carpeting
  • Encasing mattresses, box springs and pillows
  • Wash bedding weekly in hot water (130°F)
  • Use a HEPA filter-equipped vacuum


  • The National Survey of Lead and Allergens in Housing, an NIEHS study, discovered that 84.2 percent of U.S. homes had detectable dust mite allergen in their beds.
  • The American College of Allergy, Asthma, and Immunology estimates that as many as 90 percent of people with allergic asthma are sensitive to dust mites, and at least 45 percent of young people with asthma are allergic to dust mites