Duct Sealing Methods: The Best Ways to Fix Leaky Ducts

Leaky ductwork might not be obvious, but it can silently drive up your energy bills, waste energy, and even impact the air you breathe at home. If some rooms in your home are always too warm or too chilly, or if you’re noticing more dust than usual, your ductwork might be to blame. The upside? Fixing those leaks is a simple way to boost your home’s comfort, cut costs, and breathe a little easier.

This guide breaks down the best ways to seal your ductwork, helping you figure out whether to roll up your sleeves for a DIY project or call in the pros.

1. Mastic Sealant: A Durable, Long-Term Solution

Mastic sealant is a thick, gooey paste made to seal up gaps and cracks in ductwork. Use a brush, a spatula, or even your hands to apply it—just be sure to put on gloves first! Once it sets, it creates a flexible yet tough seal that can handle whatever temperature swings come its way.

Why Mastic Works Well

• Creates a secure, durable seal that lasts 
• Remains flexible to stop cracks before they start 
• Perfect for tackling both small and medium leaks

How to Apply It Properly

• Begin by giving the duct surface a good clean so the sealant sticks properly. 
• Use a brush or spatula to smoothly apply the sealant, ensuring it fills every gap you find.
• If you’re dealing with bigger openings, lay down some fiberglass mesh over the gap first, then seal it up.

Pros & Cons

Pros: Creates a tough, lasting seal and works well on all kinds of leaks. 

Cons: Can get a bit messy during application and needs time to dry. 

For a strong, long-term solution, mastic is hard to beat!

2. Foil Tape: A Simple, Quick Fix for Small Leaks

Got a small leak to fix? Ditch the duct tape—it’s not built to last. Foil tape is the real deal, designed to handle high heat and stick around for the long haul.

Foil Tape vs. Duct Tape: Why Foil Tape Outperforms

Unlike traditional duct tape that dries out and loses its grip over time, foil tape holds strong no matter how much it’s exposed to changing temperatures or airflow.

How to Use It 

• Cut a piece of foil tape a little longer than the gap you want to cover. 
• Apply it firmly to the duct, ensuring you press out any air bubbles along the way for a smooth finish.
• Overlap the edges slightly to keep things sealed tight and leak-free.

Great Ways to Use It 

Foil tape is a go-to for sealing small leaks and strengthening duct seams. It’s a lifesaver for quick fixes and DIY projects when you need something sturdy and reliable. 

Quick Tip: Keep a roll nearby—it’s surprisingly handy for all kinds of household repairs, not just ductwork!

3. Aeroseal: A High-Tech Solution for Hidden Leaks

Got leaks in hard-to-reach places? Aeroseal has you covered. This innovative technique uses a pressurized aerosol sealant to find and seal leaks deep inside your duct system—even in spots you can’t see or get to.

How the Aeroseal Process Works

A technician hooks up a smart machine to your duct system, releasing a fine mist filled with sealant particles. These tiny particles move through the ducts, sticking to any cracks or gaps they find along the way, sealing them from the inside out like magic.

Why Homeowners Choose Aeroseal

• Cuts down duct leakage by as much as 90% 
• Boosts airflow and makes your system run much more efficiently 
• Seals hard-to-reach leaks that other methods just can’t fix

What Does It Cost? 

Aeroseal needs to be installed by a pro, so it’s a bit more expensive than DIY fixes. But here’s the deal—those energy savings can really add up over time, making that upfront cost worth it. If you’re tired of dealing with those sneaky, hard-to-find leaks and want a long-term, no-hassle solution, Aeroseal could be exactly what you need.

4. Duct Insulation: Enhancing Protection and Efficiency

Even with tightly sealed ducts, energy can still slip away if they’re not properly insulated. Adding insulation helps keep the air inside your ducts at the right temperature, cutting down on energy waste and making your home feel cozier and more comfortable.

Why Insulation Matters

• Keeps your home cozy by reducing heat loss and saving energy 
• Maintains a consistent temperature throughout every room 
• Cuts down on noise by muffling sounds traveling through ducts

Top Choices for Insulation

• Fiberglass: Affordable, reliable, and a go-to option for most homes. 
• Reflective Foil Wraps: Perfect for improving thermal resistance without making things too bulky. 

Pairing quality insulation with proper sealing is the secret to keeping your ductwork efficient no matter the season.

5. DIY or Hire a Professional: What’s the Best Choice for You?

When You Can Fix It Yourself

• The leaks are small and easy to spot. 
• You’re handy with tools like mastic sealant or foil tape. 
• Your ductwork is in a spot you can easily reach. 

If the problem is minor and you’ve got access to the ducts, rolling up your sleeves for a DIY fix could save you money and get the job done quickly.

When Should You Call in the Pros? 

• You think there might be leaks in tough-to-reach spots. 
• Your energy bills are still sky-high, even after you’ve tried sealing some leaks on your own. 
• You’re looking for a long-lasting fix that won’t need constant touch-ups. 

Sometimes, DIY just isn’t enough. Professional services like Aeroseal are designed to handle tricky leaks that are hard to tackle yourself. Sure, the upfront cost might be higher, but the long-term energy savings can easily make it worth it. 

Still deciding? Start small with DIY sealing. If the results aren’t meeting your expectations, it might be time to call in the experts to get the job done right.

Keep Your Home Comfortable with Proper Duct Sealing

Leaky ducts don’t have to be an ongoing problem. Whether you opt for mastic sealant, foil tape, Aeroseal, or additional insulation, each method plays a role in improving energy efficiency and maintaining a healthier indoor environment.

Achieving year-round comfort in your home begins with properly sealed and energy-efficient ductwork. At Lakeshore Duct Cleaning, we specialize in expert inspections and sealing services to help you save energy and enjoy a cozier home. Looking to maximize your HVAC's efficiency? Contact us now and book your appointment—let’s get your system running at its best!