Sierra Club Green Home » Blog Archive » Dehumidifiers

Air dehumidifier mainly used for swimming pool...

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Sierra Club Green Home » Blog Archive » Dehumidifiers.

via Sierra Club Green Home » Blog Archive » Dehumidifiers.

via Sierra Club Green Home » Blog Archive » Dehumidifiers.

How to deal with dampness

High humidity in the summer can be uncomfortable, and musty odors in a bathroom or basement are annoying. But humidity should be kept in check for more serious reasons, too. First, there’s your health: excess moisture encourages the growth of mold and dust mites, which are known to trigger asthma attacks and cause nasal irritation, sneezing, and other respiratory discomfort. Humidity can also lead to structural problems in your home, including warped and rotten wood. It also encourages unwanted guests: rats, mice, and wood-devouring carpenter ants and termites thrive in dampness. High humidity can even boost your utility bill in summer, for the simple reason that humidity makes you feel warmer, encouraging you to crank up the air conditioner.


The higher the humidity in your house, the harder it is for water to evaporate from your skin. That’s why humidity makes you feel warm in the summer. Water vapor can also make your basement or crawl spaces musty. Since it’s a lot cooler down there, a lot more water will condense because the cool air won’t hold as much water.

The ideal humidity inside your home is around 45%. Over 50% seriously encourages growth of molds and bacteria. If any part of your home is significantly higher than 45%, you should take the steps below and, if you still have a problem, consider a dehumidifier. On the other hand, letting humidity drop below 30% in living areas can cause other problems. For more about this, see our article on humidifiers.

Top Tips

At home
Many problems with excess humidity can be eliminated or greatly reduced by taking the following simple steps to stop moisture at the source.

  • Seal cracks in basement walls and foundations. Cracks obviously admit moisture. Look for them and seal them with a high-quality concrete sealer. Where there is general dampness rather than leaks, the application of a waterproof coating on the concrete may help.
  • Check plumbing. Look for leaks, but also wrap any cold-water and drainage pipes where you see condensation forming. Also look for openings where pipes come through walls and floors and seal them with a good caulk.
  • Clean and seal gutters and downspouts. Much of the moisture in basements comes from water that soaks into the ground close to the building. The first line of defense is to make sure there are no leaks or clogs in the gutters and downspouts. Once the water reaches ground level, it should be routed at least three feet away from the house.
  • Add underground drains? Serious drainage problems may require installation of underground drainpipes close to the foundation. If you already have such a drainage system, run water through it periodically to make sure it isn’t plugged. If the water backs up, you need to unclog the system.
  • Use a properly sized fan in your bathroom.
  • Use a range hood fan in your kitchen when cooking

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