7 Signs Your Air Ducts Need Cleaning

cleaning air ducts through floor vent

Annual inspection of your air duct system to ensure it’s running smoothly? A must. Yearly air duct cleaning, though? Not a must. According to the Environmental Protection Agency (EPA) and the National Air Duct Cleaners Association (NADCA), the majority of homeowners need only clean their air ducts as needed. A few signs your air ducts need cleaning include visible mold growth, excess amounts of dust, and pest infestations, to name a few.

But First, What Are Air Ducts?

Simply put, air ducts are the channels through which your home’s air is filtered, heated or cooled, and then sent back out into your living spaces. This ductwork, which is a crucial component of your HVAC system, can be located inside your home’s walls, ceilings, and/or flooring and is typically made of:

  • sheet metal
  • fiberglass
  • steel wrapped in flexible plastic

Return ducts are the ones responsible for recycling the air in your home. They draw in the “used” air, send it through an air filter, and run it through the heating or cooling system. Supply ducts then take that recycled air and distribute it back out through vents all over your house.

7 Signs Your Air Ducts Need Cleaning

1. There is Visible Mold Growth

Ceiling mold close to air duct
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Mold is never something to play with, and if it’s forming in your duct system, that means a whole lot of mold spores are being disseminated throughout your home. Breathing in these contaminants, especially over a long period of time, can cause health problems because mold and mildew produce allergens, and sometimes, mycotoxins (naturally occurring poisonous substances). This less-than-optimal indoor air quality can result in sneezing, hay fever, itchy/watery eyes, runny nose, asthma attacks, and more. 

2. You Have a Vermin Infestation

Rodents and other pests wreaking havoc in an air duct system isn’t just the stuff of movies. Whether through cracks in unsealed ductwork or by chewing open their own access holes, everything from rats, mice, roaches, and snakes can sneak into your home’s ductwork and potentially other areas of your house.

Not only can this be a danger for you and your family if any of these vermin physically enter your living spaces, but your health can also be compromised by inhaling bacteria and viruses that may be present in the pests’ droppings, for example.

Look out for gnaw marks, shed skin, eggs, droppings, animal sounds, and musty odor — all telltale signs of a pest problem.

3. Your Energy Bills Are Suddenly Higher

It’s normal for homeowners to see small fluctuations in their energy bills — sometimes energy costs go up slightly with each new season due to increased usage of air conditioning or heating.

But, if you notice an abrupt, drastic elevation in your utility bills, this could signal dirty air ducts. Dirty ducts, meaning there’s an excessive amount of dust buildup, can potentially hinder airflow, energy efficiency, and overall function of your HVAC unit.

4. There’s Been Recent Construction

If you’ve ever watched a home improvement show, you know that building a new home or renovating an existing one brings on all types of debris — we’re talking particulate matter from drywall, wood, asphalt, and the like.

Soon after construction is complete, be sure to schedule a thorough cleaning of your ducts to clear out all that gunk.

5. Your Home’s Air Smells Musty

We’re all familiar with that brief but “odd” smell that flows from our vents any time we switch over from our cooling system to our heating system (and vice versa) for the first time in months. But a musty smell that’s ongoing? Yeah, that’s not normal — and it could indicate a pest infestation, mold growth, or mildew, meaning you need air duct cleaning.

6. There is Excess Dust in Your Ducts

dirty air duct return
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A little dust won’t hurt you — most of it sticks to the air duct’s walls, anyway. The same is true for any dust and other particulate matter you may occasionally encounter on your air vents and vent covers. With a quick wipe or run of the vacuum, they’ll be clean once again.

On the flip side, an extreme buildup of dust and dirt can obstruct airflow, compromise ducts’ air filters, and trigger allergic reactions, which brings us to our next point.

7. Your Allergies Have Gotten Worse

It could be a good idea to have an inspection and air duct cleaning if you or other members of your family’s allergies, asthma, and/or other health problems have become exacerbated. High amounts of pollutants like pet dander, pollen, dust, and dirt can increase sneezing, itchy/watery eyes, and other allergy symptoms.

FAQ About Air Duct Cleaning

How often should I clean my air ducts?

There is no set schedule on how often homeowners should clean air ducts. The National Air Duct Cleaners Association (NADCA) and the Environmental Protection Agency (EPA) advise people to only clean their air ducts as necessary. 

That being said, every household has its own needs, and if you or those you live with already suffer from allergies or asthma, for example, you may learn you need air duct cleaning services more often than the general population.

Note: Air ducts should be inspected every year.

Does air duct cleaning prevent health problems?

Dust and other allergens in air ducts have never been proven to pose a threat to human health. Additionally, there is no proof that expert duct cleaners can make indoor air quality better, since pollutants enter homes more frequently through clothing/footwear worn outside, smokers in the home, and cleaning chemicals.

Besides air ducts, what are the other parts of an HVAC system?

Heating, ventilation, and air conditioning units (HVAC units) are what keep homes temperature-controlled and comfy, no matter the season. In addition to air ducts, HVACs are comprised of the following: 

  • air conditioner
  • thermostat
  • heat pump/furnace
  • air handler

When to Hire a Professional

Unless there are extenuating conditions (obvious mold, thick layers of dust and grime, or pest infestations, etc.), you won’t need to have your air ducts cleaned. If you do find yourself in need of a professional duct cleaning company near you, be sure to research them well. Here’s how to know you’ve found the right fit:

  • The company has good reviews.
  • They are licensed and insured.
  • They belong to the NADCA.
  • They promise to inspect your ducts first.
  • They don’t offer steep “whole-house” discounts.

Once you’ve hired a duct-cleaning pro, they’ll evaluate your air duct system, cover your flooring and furniture, vacuum the ducts, fix any damage they discover, and provide you with a report of everything they did for your records.

Note: If there is visible mold, you must first engage a mold removal professional in your area to take care of that issue. Experts in mold removal are not the same as air duct cleaners.

Main Photo Credit: Kubrak78 / Canva Pro / License

Andréa Butler

Andréa Butler is a writer and editor. And while she hasn't been blessed with DIY skills herself, she is adept at writing and enjoys sharing home improvement tips and pool care guides for the true DIYers out there.