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Excess Humidity: Causes & Solutions

August 1, 2015

In Tennessee, the humidity can be unbearable at times, making air-conditioning a necessity.  Air-conditioning removes the excess humidity and thus makes us feel more comfortable. But signs your home suffers from excess humidity include: mold, mildew, dust mites, bacteria, rotting or warping wood inside your home (cabinets, wall beams, floors, furniture), or peeling paint; plus, the moisture attracts pests (even snakes!).  What can be done? Perhaps you’ve contemplated getting a dehumidifier, but even the best dehumidifier may not work effectively if too much outside moisture is seeping into your home.

Humidity Checklist

Before making an expensive dehumidifier purchase, be sure you have investigated these issues:

  • Check that gutters aren’t clogged and that downspouts are directing rainwater at least 3 feet away from the house. Grade your property so that rainwater flows away from the foundation.
  • Keep the duct for your clothes dryer properly vented to the outside, making sure that it isn’t clogged or leaking.
  • Run an exhaust fan when showering, and squeegee or wipe down shower walls afterward.
  • When cooking, use a range hood or exhaust fan that vents outdoors.
  • Use ceiling fans and room fans to keep the air circulated. This will help your air-conditioner be more efficient.
  • Look for leaks in your existing ductwork that need to be repaired. Leaks let cool air escape into the attic or crawl space. That air loss creates negative pressure inside, causing it to suck in humid air through cracks. See about getting your ducts tested and sealed.
  • Check your plumbing for leaks and condensation, especially in the basement, and insulate pipes.
  • If you have extensive water or drainage problems, it may require a sump pump and installing drains outside.

Basements & Crawlspaces are the Most Problematic

Most HVAC systems naturally pull air from the lower areas of your home upwards throughout the living space; thus a damp basement or crawlspace can affect your whole house. Crawlspaces, while they may have fewer cubic feet due to the lower ceiling height are actually harder to dehumidify because they require more airflow (air pressure) to circulate air.  This is why a good crawlspace dehumidifier costs more than an average home dehumidifier. Waterproof your crawlspace and basement, and ensure it is properly insulated.  Fill holes and cracks in concrete block with hydraulic cement and paint the concrete block with a water-proof coating like Dry-Lok. If your crawlspace has a dirt floor, create a vapor barrier to reduce the continual evaporation of moisture from the ground.

Is your HVAC to Blame?

Lastly, your HVAC system itself may be to blame for your excessive moisture problem! If you over-sized your system thinking it would make you cooler and not run as hard in the summer, think again! Air conditioners only dehumidify when they are running, and an oversized unit may not be running long enough to remove the moisture from the air (it cycles off too quickly). Check out a previous post we did on right-sizing your system entitled “Think Bigger is Better? Not When it Comes to Cooling!”

After you’ve addressed these causes of excess humidity, then you can see if a dehumidifier is needed. We did a post recently about central dehumidifiers, so check that out, too!