Moisture Management

A very significant part of keeping a healthy home involves managing moisture. The relative humidity of an environment can either contribute to or prevent respiratory illness as well as variety of other health effects. Excess moisture also creates an environment conducive to the growth of dust mites, mold, bacteria, insects, and wood rot.

One of the major problems associated with moisture is mold growth. Mold produce chemicals known as mycotoxins, some of which are known to be harmful. The difficulty in dealing with mold is that it is capable of growing on almost any surface as long as there is oxygen and moisture present. Being that oxygen will always be present, the only factor that you can account for is the moisture content in the air. Though impossible to eliminate mold entirely in an indoor environment, it can be controlled with relative ease.

In order to maintain the structural integrity, durability, and value of the house, it is important to keep moisture under control.


Relative humidity (RH) is an import concept in measuring moisture. When RH is at 100%, water vapor in the air changes to its liquid form and thus, condensation forms. This condensation is absolutely damaging for a home environment. It is very easy to measure RH using a moisture or humidity meter. These are available at hardware stores for anywhere from $10 – $50. The ideal range is for RH to fall between 30 – 50%.

If visible mold growth is present, there is no need to test or sample the growth. There are no EPA or federal standards for mold growth. If there is visible mold growth, it is usually necessary to take steps to reduce the moisture content your home.


Maintaining a RH of below 50% prevents the mold and mildew growth and inhibits bacteria growth as well dust mite infestations.

Preventive Measures

  • Clean up water leaks/spills as soon as possible.
  • Clean/repair roof gutters regularly.
  • Keep indoor humidity low.
  • Use air conditioners and/or de-humidifiers to reduce humidity.
  • Open windows/use exhaust fans.

If you see any condensation in the home, wipe it away immediately to reduce moisture content.

  • To reduce condensation, reducing humidity is a major step.
  • Increase ventilation through open doors/ windows and use fans as needed.
  • Increase air temperature.
  • Adding insulation on cold surfaces will decrease condensation. Contact a professional contractor to install.

In the event that: Heating/ventilation system/air conditioning (HVAC) system is contaminated with mold due to moisture problems…

The EPA does not recommend routine cleaning of air ducts. The most effective measure is to prevent moisture problems.

If substantial visible mold is present in the air ducts, contact a professional for cleaning. To be sure, send a sample of mold to a microbiology laboratory to determine whether the substance is actually mold and a similar substance. This can be done for approximately $50.

If cleaning is necessary:

  • Do not hire duct cleaners who claim health benefits to duct cleaning as that is still unsubstantiated.
  • Do not allow chemical biocides/treatments unless you fully understand the potential risks.
  • Contact local county/city office or the Better Business Bureau (BBB) to find if there have been any complaints.
  • Make sure they comply with NADCA’s air duct cleaning standards.

The most effective method to deal with moisture problems is to simply make sure that RH levels are never beyond the recommended 30 – 50% level. Contact a professional contractor for moisture control.

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Cambridge, MA 02142