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5 Signs You Need a Portable Dehumidifier

From foggy windows to funky smells, here are five clues you might need a dehumidifier.

Brian Bennett Former Senior writer
Brian Bennett is a former senior writer for the home and outdoor section at CNET.
Megan Wollerton Former Senior Writer/Editor
Brian Bennett
3 min read
A cat looks through a window with condensation

Foggy windows? That's one sign you might need a dehumidifier.

Huseyin Demirci/Anadolu Agency/Getty Images

Overly damp, humid air in your home isn't just uncomfortable, it's unhealthy. If left unchecked, high levels of humidity can damage your home. A dehumidifier can help you avoid the resulting repairs.

Dehumidifiers range in price from $100 to $1,000, depending on how much square footage you need to dehumidify. Choosing the right model for your home depends on your exact needs -- and this guide will help you determine just that.

Here are some signs you need a dehumidifier:

  • A damp basement
  • Condensation on walls and windows
  • Musty odors
  • Mold or mildew growth

A damp basement

In many homes, it's often the basement that suffers from high humidity. Does your basement feel damp or consistently have a higher relative humidity than other areas of your home? If so -- and you haven't noticed leaks or other evidence of water intrusion -- a dehumidifier can help.

This can be the case even if your house is equipped with a central air conditioner, or HVAC. During hot and humid summer months, your HVAC may have trouble recirculating cool, dry (AC treated) air to the basement, especially if your home lacks a basement return vent.

During the fall and spring seasons, when the HVAC usually won't be running, damp air can also build up inside basements. Unless your basement is superbly insulated, it's natural for moisture to seep into basement air through the foundation.

Stubbornly high humidity

According to the Environmental Protection Agency, the optimal indoor humidity range is between 35 and 50%. A relative humidity above 60% is generally considered too high. These conditions aren't merely uncomfortable, though they'll either be cold and clammy or hot and sticky. They also promote the growth of mold, which is a known health risk.

Consistently high humidity throughout the entire house is another warning sign, which can be determined with smart thermostats that can read humidity levels. Ecobee and Nest can both read humidity. Or you can buy an inexpensive humidity meter (which should cost between $10 and $50) to take readings.

Prolonged exposure to high humidity can cause wood to rot and the breakdown of other building materials such as gypsum board, paints, varnishes and metal wiring. The presence of moisture can pave the way for destructive pests too, including termites and carpenter ants.


A portable dehumidifier in the right spot can pull unwanted moisture from the air.

Chris Monroe/CNET


Condensation on windows and walls is a tell-tale indicator that your home is too humid. This moisture build-up occurs during the cold winter months when outside temperatures plummet compared with significantly higher indoor temperatures. Cold surfaces, including window glass and poorly-insulated walls, cause water within warm and humid indoor air to condense. If you see this often, chances are good you have an indoor humidity problem.

Poor ventilation or drafts

Environmental conditions can play a big role in your home's indoor humidity. For instance, maybe the climate where you live tends to be wet year-round. This reality, combined with a house that lets too much outside air inside, will create elevated moisture levels indoors. Drafty windows and doors are another likely culprit.

Poorly ventilated homes can create similar problems, but for a different reason. If your house is well insulated, it will hold onto excess moisture. Steamy showers in bathrooms without exhaust fans, unventilated kitchens (with no vented hood system) and laundry rooms filled with wet clothes are other sources of humidity issues.

Musty smells or visible mold: The worst-case scenario

Humid environments encourage mold and mildew to form, which can result in mold-related health issues. Actively growing mold indoors releases spores and other toxins, which often smell musty or foul. These airborne contaminants may trigger allergic reactions and attacks for asthmatic individuals. They can also act as irritants to the eyes, nose and throats of otherwise healthy individuals.

If you find mold spots on walls, floors, or other locations within the home, you've got moisture problems. The EPA advises you to act quickly in this situation by addressing the root cause. A dehumidifier probably won't cure your water condition, which may be a leaky pipe or poor rainwater drainage. Still, a dehumidifier could help halt further damage while you find a permanent fix.

For more information, check out our portable dehumidifier buying guide.

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