What You Need to Know About Duct Leakage

happy cat lying on floor in front of the furnace register

This may well be the first time you’ve thought about your home’s air ducts since you moved in. Why should you? They’re there, they do their thing, and that’s it.

Or is it?

If you are experiencing any kind of issue with your home heating or cooling equipment, and you’re not considering your ductwork, you could be missing the crux of the issue.

Let’s start at the beginning.

What is Ductwork?

According to the Department of Energy, your duct system is a “branching network of tubes in walls, floors, and ceilings. Made of sheet metal, fiberglass, or other materials, ducts carry air from your home’s furnace and central air conditioner to each room.” 

And, if there are any cracks, holes, or gaps in your duct system, this can result in leaks that cause a variety of issues in your home HVAC. Leaks occur most commonly in the attic, crawlspaces, basements, and garages – places where the ducts themselves are exposed.

Let’s look at some of the problems caused by leaky ductwork.

Illustration of airflow before Aeroseal installation
Health Concerns and Indoor Air Quality

Cartoon icon of dust and allergens

Besides just the loss of conditioned air, leaky ducts can result in negative air pressure, which actually pulls in the dust, allergens, and other airborne contaminants from the attic, basement, or crawl space, and spews it into your main living areas. This can also lead to clogged air filters, which can also worsen the air quality problems in your home. So, if your allergies are flaring up, this could be part of the reason. In addition, poorly-maintained ducts are a literal breeding ground for mold, mildew, and other fungi that can cause breathing problems, aggravate asthma, or cause other illnesses.

Hot and Cold Spots

Fix hot and cold spots

Leaky ductwork can also contribute to uneven temperatures, which you’ll notice in the way of hot and cold spots throughout your house. Repairing your duct leaks or sealing all your ducts can help eliminate this problem by improving the airflow in your home and making every room comfortable.

High Energy Bills and Shorter System Life

Cartoon illustration of paper money bills

When the air from your forced air heating or air conditioning isn’t going where it’s supposed to, that means your system has to work harder. If you notice your system is running constantly, it’s a good indication that you have leaky ducts somewhere. A harder working system is a less efficient system. This means, not only are you not getting the efficiency you paid for and running a less green home, but you’re likely also paying MORE in the way of higher energy bills.

Energy Conservation

Two leaves representing environmentally green

When you have a leaky duct system, you may be losing as much as 40% of the air moving through your home. This equates approximately to 20% of the energy you’re paying for each month. This means you’re using 20% more energy than you need to be. This clearly goes against conservation standards and means you’re not living as green as you could be. Having your ducts sealed can save that 40% of airflow and 20 % of energy. Your home will be more efficient, meaning you are doing the right things for your home, your family, and for the planet.


Cartooon illustration of air flowing out of a register

One thing many people are unaware of is that appliances in your home – the stove, the dryer, the water heater, the furnace – give off combustion gases as they run. These gases enter your home’s duct system through their individual ventilation processes. If your ducts have leaks or gaps, those gases – including carbon monoxide, which can be deadly – enter the air in your living spaces through those gaps, and poison the air you and your family breathe. This is known as “backdrafting.” While you may have a carbon monoxide detector in your home to warn you when backdrafting occurs and these gases reach dangerous levels, it’s a better idea to prevent this buildup at the source. Sealing your ducts helps prevent these backdrafts, creating higher indoor air quality, and helping keep your family safe.

What Can You Do?

Here are some things to consider for making sure your home’s ductwork is in working order.

  • Have a contractor inspect your entire system, including those ducts and vents in, to, and from places that aren’t conditioned, like basements, crawl spaces, and attics.
  • Ask your contractor if your system’s supply and return air balance is adequate. It’s common for systems to have air return ducts that are too small for the square footage of the home.
  • Straighten out any kinks, tangles, or crushed areas in your ductwork, and repair any damaged or disconnected ducts.
  • Seal leaks and connection gaps with duct tape – yes, that duct tape – mastic or metal tape, or with an aerosol-based sealant like Aeroseal. Aeroseal Duct Sealing from the inside can reduce a home’s energy leaks by up to 40%.
  • Ensure that all registers and grills are sealed flush and tightly to the ducts.
  • Insulate the ducts in the previously-mentioned unconditioned areas with duct insulation that is rated R-value of 6 or higher.
Illustration of home air flow after Aeroseal installation

  • Change your filter any time you upgrade your duct system – and every 3 months, as well. Higher-quality filters can create higher efficiencies in your home’s energy use.
  • Make sure your contractor evaluates the home’s airflow AFTER the work is completed. They should also test for back-drafting with a combustion safety test.

Call All American Heating if we can answer any questions or offer assistance in reducing duct leakage in your home.


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