Mold and HVAC Ductwork image

Clearing the Air: How to Handle Mold Issues in Your HVAC Ducts

Crawlspaces, basement, attic, kitchen, and shower are a few places that come to mind when you think about places you can find mold in your home. Many people tend to forget about their HVAC duct work, which is a very common place for mold to grow. Duct work actually is one of the fastest ways for mold to spread throughout your home or building because it circulates the air throughout your home. The air that passes through the duct work can pick up mold spores and spread them to various rooms in your house.

What causes mold in the duct work?

HVAC duct work is a perfect environment for mold growth: it’s a dark space, there is moisture (from the condensation that tends to develop), and there is food. Dust and other outside debris tend to build up in the duct work which is the perfect food source for mold as it usually is a mix of organic and inorganic material. This creates the ideal conditions for mold to develop, grow and spread.

There are also some factors that can make your system more prone to mold growth:

  • Oversized HVAC unit
  • Setting your AC temperature too low
  • Duct work leaks

What are signs of mold in the HVAC duct work?

Mold, especially in the early stages, can be hard to detect. We recommend calling in a certified mold inspector as they can perform an air test or take a lift tape sample to determine if mold is present in your ducts. Other signs that mold is present in your HVAC duct work are:

  • Musty odor that is stronger when your HVAC system is running
  • Visible mold around your vents or returns
  • Nose, throat or eye irritation when you are in the conditioned space
  • Allergy like symptoms
  • Noticeable leaks around your HVAC system
  • Blocked drip pan

How to remove the mold and clean the duct work?

Hiring a professional duct cleaning company and a certified mold specialist is the best way to guarantee the mold is removed completely and safely. It will be more expensive than attempting to do it yourself, but it will be well worth the investment. Regular home cleaners will not remove all of the mold and will likely leave enough behind for the mold to quickly and easily grow back. Additionally, it is easy to damage your HVAC system or duct work when trying to clean the duct work yourself. Professionals will use the correct equipment to keep the mold and debris that is removed from your ducts from spreading through your house.

How to prevent the mold from growing in your ductwork?

Once the ducts have been cleaned and the mold has been removed it is important to take steps to prevent mold from developing again. Here are somethings you can do the help prevent mold growth in your duct work:

  • Change your air filters regularly
  • Insulate duct work to prevent condensation
  • Clean your drip pan regularly
  • Use a dehumidifier in moist areas
  • Add ventilation, if needed, in rooms with higher humidity
  • Clean your HVAC duct work periodically (at least every 3-5 years)

Unsure if you have mold in your HVAC duct work? Call your local certified mold expert!

1 reply
  1. Eli Richardson
    Eli Richardson says:

    It really helped when you talked about how a musty odor in your home might be a sign of a mold infestation. My wife and I just came back from our vacation. When we arrived home, everything looked normal, but when we turned our HVAC system on, we noticed a weird smell coming from it. That’s why we’re researching what could be the source of it. After reading your piece, we think it’ll be better to get a professional to help us know if we have mold or not. We’re grateful for helping us learn what to do if we find mold in our HVAC system.

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