If your house feels clammy even with the air conditioner running, the windows fog up on summer mornings, or there’s a musty smell you can’t place, humidity is probably to blame. In Eastern North Carolina it’s a fact of life from late spring into fall, and it doesn’t stay outside.
High indoor humidity does more than make a room feel sticky. It feeds mold and mildew, warps wood floors and trim, and makes a home more inviting to pests that need moisture, like cockroaches, silverfish and termites. Dust mites, a common allergy trigger, also thrive in damp air.
What humidity level should you aim for?
The EPA recommends keeping indoor humidity below 60 percent, and ideally between 30 and 50 percent. It’s hard to manage what you don’t measure, so pick up an inexpensive digital hygrometer and check a few rooms. Readings that sit in the high 50s or above through the summer mean it’s time to act.
Here are six ways to bring it down.
1. Let your air conditioner do its job
Your AC is a dehumidifier as well as a cooler. As warm air passes over the cold coil, moisture condenses and drains away. A few habits help it work better:
- Set the thermostat fan to Auto, not On. When the fan runs nonstop, it blows air across the wet coil between cooling cycles and can put some of that moisture back into the house.
- Change the filter on schedule. A clogged filter cuts airflow and makes the whole system work harder.
- Keep the condensate drain clear. A blocked line can back up and leak.
An oversized unit is another common reason a home stays humid. It cools the house so fast that it shuts off before it has time to pull much moisture out. If your home is cool but still feels damp, have an HVAC contractor take a look.
2. Run a dehumidifier where it’s needed
For a damp room, a portable dehumidifier makes a real difference. Set it around 45 to 50 percent, and if you can, run its hose to a drain so you’re not emptying a bucket every day. Homes that stay humid even with a healthy AC system may do better with a whole-house dehumidifier tied into the ductwork, or one installed in a sealed crawl space.
3. Vent moisture at the source
Cooking, showers and laundry put a surprising amount of water into the air. Run the bathroom fan during every shower and keep it going until the room clears. Use the range hood when you cook, especially when you’re boiling water. Make sure the dryer vents outside and the vent line isn’t crushed, clogged or disconnected.
It’s also worth confirming your bath fans actually reach the outdoors. A fan that ends in the attic just moves wet air somewhere you can’t see it.
4. Dry out the crawl space
In homes built over a crawl space, a lot of moisture can come from underneath the floor. Bare soil, a torn vapor barrier and standing water after storms can keep crawl space air damp all year, and some of that air makes its way up into the house.
Warning signs include a musty smell indoors, cupping hardwood floors, sweating ductwork and wood that feels damp. A damp crawl space is also prime territory for termites. If that sounds familiar, our moisture control service can help, and a termite inspection is free.
5. Keep rainwater away from the foundation
Water that pools against the house finds its way into crawl spaces and walls. Clean your gutters, add extensions so downspouts empty several feet from the house, and fill low spots so the soil slopes away from the foundation. Our post on how to improve drainage covers this in more depth.
6. Cut down on everyday moisture
Small sources add up. Fix dripping faucets and running toilets. Hang wet laundry outside instead of on a rack in the house. Put lids on pots while you cook. Keep firewood outdoors, and go easy on houseplants in a room that’s already damp. A big aquarium adds moisture too.
One more tip that surprises people. Opening the windows doesn’t always help. On a hot, muggy day, outdoor air often carries more moisture than the air inside, so open windows can actually raise humidity. Save the fresh air for cooler, drier days.
When humidity points to a bigger problem
If you’ve tried the basics and the house still feels damp, something else may be going on, like a hidden plumbing leak, a crawl space that takes on water after storms or ductwork leaking in the attic. An inspection with moisture readings and infrared scanning can help narrow it down. Keeping humidity in check is also one of the best ways to prevent mold growth and keep pests from settling in.
