How Long Does Ductwork Last?

Were you told during a recent AC tune-up that your ductwork may need repair or replacement?

It’s a common recommendation from HVAC technicians, but not always easy for homeowners to evaluate.

Ducts are out of sight, and unlike your AC unit, they don’t have a clear “failure point.” They can work reasonably well for years while insulation breaks down and leaks or airflow restrictions develop.

So how long is ductwork actually supposed to last, and when does replacement start to make sense?

How to Tell What Type of Ductwork You Have

There are three types of ductwork common in Dallas–Fort Worth homes, and you can usually identify them with a quick visual check.

Flexible duct (flex duct) is the most common in homes built from the 1990s to today. It looks like a round, bendable tube with a plastic outer jacket and insulation wrapped around it. You’ll often see it draped between rafters or suspended with straps.

Sheet metal ducts are rigid, smooth-sided ducts, typically silver or gray. They’re more common in older homes or certain custom installations. They may be wrapped in insulation or have insulation installed separately.

Duct board or fiberglass-lined ducts are boxy, rectangular ducts made from compressed fiberglass panels. They’re less common in newer homes but were used more frequently in past decades.

Many homes use a combination of materials, with a sheet metal trunk line and flexible duct branching off to individual rooms. Older homes may also have a mix of materials depending on past upgrades.

Average Lifespan of Different Types of Ductwork

Ductwork doesn’t have a fixed expiration date, but each material has a general lifespan range under typical conditions.

• Flexible duct typically lasts around 10 to 20 years. In hot attics like those in DFW, the outer jacket and insulation can degrade faster, especially if the duct is poorly supported or kinked.
• Sheet metal ducts often last 20 to 30 years or longer. The metal itself is durable, but joints, seals and insulation can still fail over time.
• Duct board / fiberglass ducts usually fall somewhere in the 15 to 25-year range. They can deteriorate if exposed to moisture or physical damage.

In many cases, ducts don’t “fail” all at once. Performance declines gradually as leaks develop, airflow becomes restricted or insulation breaks down.

What Causes Ductwork to Wear Out Faster

Several factors can shorten the lifespan of ductwork, especially in North Texas homes.

• Extreme attic heat: Attic temperatures regularly exceed 120°F in the summer, which can break down insulation and outer materials over time.
• Poor installation: Kinks, sharp bends or long unsupported runs in flex duct can restrict airflow and lead to early failure.
• Air leaks at joints and connections: Over time, seals can loosen or degrade, allowing conditioned air to escape into the attic.
• Physical damage: Rodents, foot traffic in the attic or other work being done near ducts can crush or tear sections.
• Aging insulation: Even if the duct itself is intact, worn insulation reduces efficiency and can impact comfort.

Signs Your Ductwork May Need to Be Replaced

Because duct problems develop gradually, the symptoms aren’t always obvious at first.

• Uneven temperatures between rooms
• Weak airflow from certain vents
• Higher energy bills without a clear cause
• Excessive dust or reduced indoor air quality
• Whistling or air noise from leaks
• Visible damage in the attic, such as crushed or disconnected ducts

These issues are often attributed to the AC system itself, but the ductwork is frequently part of the problem.

Can Ductwork Be Repaired Instead of Replaced

Not every issue requires full replacement. In some cases, targeted repairs can extend the life of your duct system.

• Sealing small leaks at joints or connections
• Replacing isolated damaged sections of flex duct
• Reconnecting loose or disconnected runs
• Adding insulation in certain areas

Repairs become less practical when problems are widespread or the duct system is already near the end of its expected lifespan.

When It Makes Sense to Replace Ductwork

• The ductwork is 15–20+ years old and showing signs of deterioration
• There are widespread leaks, damage or airflow issues
• The system was poorly designed or undersized from the start
• You’re replacing your AC system and want to address efficiency and comfort at the same time
• Repairs would only provide short-term improvements

With proper installation, flex duct can perform optimally for 15–20 years, while sealed metal ductwork can often last 20+ years with little to no maintenance or repairs other than occasional duct cleaning.

Have Your Ductwork Evaluated Before It Causes Bigger Problems

Tom’s Mechanical provides duct inspections, repairs and replacements for homeowners throughout Arlington, Fort Worth and the surrounding DFW area. If you’ve been told your ducts are an issue, call us at 817-277-4493 to schedule an assessment.