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What Causes Air Ducts to Leak?

Atlanta Heating & Air Solutions Mabelton
Frozen cable conditioner Atlanta Heating & Air Solutions

You can expect higher heating and cooling costs if your home has leaky air ducts. According to Energy Star, in fact, approximately 20% of a typical home’s conditioned air is lost through leaky air ducts. It won’t necessarily affect your furnace’s or air conditioning system’s ability to create conditioned air. Nonetheless, leaky air ducts will force these systems to run for longer, resulting in higher heating and cooling costs.

Loose Fittings

Loose fittings can cause air ducts to leak. Fittings are used to connect air ducts. There are elbow fittings, for instance, that connect air ducts around turns, and there are branch fittings that connect a single air duct to two air ducts. Regardless, if a fitting comes loose, it may create a leak that allows conditioned air to escape.


If your home has a pest infestation, you may experience leaky air ducts. Air ducts are insulated, which many common household pests use as bedding material. Mice, squirrels, possums and raccoons may create nests out of air duct insulation. As they tear apart your air ducts, they’ll inevitably create leaks.

High Humidity

High humidity can cause your air ducts to leak. All homes have at least some humidity. Humidity is airborne moisture vapor, and here in the Southeast, there’s always some moisture vapor in the air. But if your home has excessively high humidity, it may cause your air ducts to leak. All of the moisture vapor in the air will saturate your air ducts, which can lead to damage that manifests in the form of a leak.


Closed Air Vents

Another common cause of leaky air ducts is closed air vents. If you close most or all of the air vents in your home, it will increase the ductwork pressure. And too much pressure can cause leaks. Closing a few air vents typically isn’t a concern, but you shouldn’t close too many air vents. Otherwise, the ductwork pressure may increase to the point where it causes a leak.


Sometimes air ducts leak due to age. Most air ducts have a lifespan of about 10 to 15 years. If your air ducts are approaching the one-decade mark, you may want to replace them. Even if they aren’t leaking now, they may begin to leak soon. Buying new air ducts is a smart investment that will minimize the risk of costly leaks.

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