Preventing Mold in Air Ducts- The Moisture Connection you need to know

Being a homeowner is one of the most exciting times of many Americans lives. While you might get to hang your picture-frames without losing a security deposit, you also become solely responsible for high-ticket issues, one of the most expensive to fix or replace being your HVAC.

Excess moisture on or within your air ducts can lead to complications such as mold, and the rapid decline of your system as a whole. Understanding the conditions and why moisture accumulates can help you prevent a hefty monthly bill. If you are already concerned about moisture buildup, it’s not too late! There are many options to prevent and treat existing concerns.

A relatively common mold type, Aspergillus, is present as air-borne spores in the natural world. In healthy individuals, our lungs are designed to expel this as we breathe. What you don’t want is mold inside of your home. It can quickly become serious and potentially costly to remove. For something that can wreck such havoc, it is surprising that mold only needs a few ingredients to begin its plight.

  • Damp and dark environments.
  • Organic food sources like cardboard, wood, and some cotton materials.


Mold can appear in a variety of colors and have a distinct fuzzy appearance. When you are inside, constantly breathing in spores, health concerns can become the first symptom. You very well could not see the mold before your body begins to react! Acute, or new, allergy-type symptoms, respiratory concerns, and damp, musty odors should be considered as an indication for mold inside of your home.

Under the right circumstances, mold will take hold, and what better way for it to spread than through the ductwork that flows throughout your home? Moisture plays a key role in cultivating the right environment for spore growth. This is why it’s imperative for homeowners to stay on top of routine air duct maintenance and be prompt with repairs for water leaks. Even after successfully drying up excess water, mold can live in dry environments for variable amounts of time.

What causes Moisture in your Air Ducts?

It can be puzzling to figure out why you have excess moisture. You may have a pipe burst, or perhaps unusual rain amounts cause a minor flood in your home. However, the issue is often less easy to identify.

Moisture is introduced into the environment through condensation. When you have cool, conditioned air meeting with hot air, it causes the water vapors to settle on or inside your air ducts. Believe it or not, the environment you live in plays a major role in how hard your HVAC system has to work! Notoriously humid areas, such as the southeast, have extremely high dew points.


  • In laymen’s terms, dew point is the measurement of water vapor in the air.
  • You should aim to keep your home’s humidity level between 40-60%.
  • This will prevent your system from working overtime to dissipate moisture.

High Indoor Humidity Levels might look like:

  • Condensation on your windows.
  • A damp, moist and sometimes cold feel to the air.
  • Your AC unit turns on and off multiple times an hour.

Can you Prevent Moisture inside of your Home?

Fortunately, there are many options to bulk up your battle against high indoor humidity rates! You want to keep warm outside air, outside, so check your crawl spaces, attics, and spaces surrounding your HVAC.

  • Proper and sufficient insulation will be one of the first steps in preventing moisture.
  • Correctly sealed air ducts will have a lower risk of developing condensation.
  • Hot air can’t get inside if there are no access points!
  • Making sure that your thermostat is set on auto will help your system run when it actually needs to be running.

Replacing air filters on a routine basis will prevent debris build up.


Investing in a dehumidifier can help draw excess moisture out of the air.

Zero in on the Process

Your ductwork plays a vital role in distributing and filtering the air within your home. When moisture accumulates, it might drip, causing:

Air Duct Cleaning Columbia - Before
air duct after
  • Leaks into your ceiling and floors.
  • Corrosion of structural pieces of your home.
  • Wet insulation that will no longer function properly. Even after it dries!

Constant run-times, hiking up both your energy consumption and your monthly bill.
Your HVAC has a greater chance of failure when it’s put through long-term, continuous strain.
Remember, mold thrives in damp environments. It only takes 48 hours for the moisture in your air ducts to turn into mold. Once present, the small spores take flight throughout the ductwork in your home. As your AC unit turns on, it will begin to spread mold through the vents in your floors and ceilings.

I think I have mold! What can I do?

The Environmental Protection Agency (EPA) recommends hiring professionals for mold sources greater than 10 square feet in size. Regardless, routine air duct maintenance will actively prevent build up and corrosion. This is recommended to be done every 3-5 years. When you hire a professional air duct technician, they will check for leaks, broken parts, and ventilation issues from blocked vents.

Most air duct cleaning companies also offer mold remediation services. Not all mold concerns are condemnable if caught early enough! Your air duct professional will help eradicate the mold from its source. More importantly, they will investigate the functions of your air ducts to prevent potential new moisture zones.

Finally, check your homeowner’s insurance policy. Mold can be expensive to treat, especially with the added costs of having to replace parts within your air ducts. According to a recent report from U.S.News, “A standard insurance policy should cover a mold claim…caused by a covered peril that is sudden or accidental in nature.”

A Not-So-Perfect Combination

Moisture is one of the few components in creating the right environment for mold growth. It is imperative to have your air ducts routinely inspected and keep your dew point levels low to help prevent moisture. Not only is moisture the basis for mold, but it can also cause leaks and create wet insulation. When your air ducts are compromised, your HVAC system has to work overtime. Take care to change your filters regularly and check for drips, broken seals, and blocked vents. Your home deserves to breathe, and you deserve to enjoy being a homeowner!

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Here at Air Duct Charleston, we’re always ready to assist you for your Air Duct and Dryer Vent Cleaning Service in Charleston, SC. We can help you with any Air Duct and Dryer Vent Cleaning Service, please call us at (843) 608-8042 or get a Free Online FREE Estimate