• Repairing Leaky HVAC Ducts


    According to the US Department of Energy, the average house loses 20 to 30 percent of treated air through leaks and holes in the ductwork and ducts that don’t fit tightly together.
    This causes you to pay significantly higher heating and air conditioning bills than necessary.
    The good news is that there are ways to better seal those ducts to prevent the loss of heating and cooled air, conserving energy and cutting your costs too.
    The temperature throughout your home will be more balanced too, increasing indoor comfort. Some of the work might by DIY for handy homeowners, and an HVAC contractor can handle what you don’t want to do on your own.
    Depending on the extent of the problem, repairs could take a few hours to several days.

    HVAC Duct Sealing Troubleshooting and Repair 

    It’s our goal in this repair guide to help you decide whether the duct repairs are a DIY project or you’d be better off hiring a pro for the work.
    We’ll also discuss duct repair costs for DIY and professional projects. A section on tips gives an overview of what you’ll run into on the project, so you’ll know what to expect.
    Tips for saving money on leaky ductwork repair are included.
    Finally, there are links below to online resources that will help you understand the scope of the issue and what can be done to rectify it.

    These tips will help you do the job yourself or know what a professional HVAC contractor should be doing. We provide a supplies and tools list below too. Knowing where leaks are occurring is the first thing you need to discover.

    • One method for finding leaks is to tape off all heat registers, turn on the blower motor and listen for leaks and feel for air coming out
    • Another safe method is to brush the duct seams and joints with a small soft duster to see if escaping air causing the bristles of the duster to move
    • On sheet metal ducts, look for dust streaks caused by air escaping out of a duct joint
    • All fabric-backed duct tape should be removed from duct joints and replaced with mastic  backed tape or foil duct tape
    • Every joint where two duct pieces come together should be sealed with mastic or foil tape
    • Also check the fit of ductwork to every register and, where possible, seal gaps with mastic or caulk or tape the connection to prevent the loss of treated air
    • If removing the drywall in a home, use the opportunity to take down ductwork normally hidden in the walls, seal all joints with mastic and return it to the wall cavity
    • In new construction projects, seal the joints in the ductwork before the ducts are installed
    • Wear sturdy gloves when working with sheet metal because corners can be sharp
    • Wear eye protection from dust and metal shavings in ductwork
    • Tearing off drywall for the sole purpose of sealing ducts is NOT a cost-effective repair

    HVAC Duct Sealing Costs

    This really can be a DIY job if you have time, a good ladder, safety equipment and basic skills.

    DIY Duct Sealing Costs: Watch a video or two online to get the hang of what you’ll be doing. It’s quite easy. Here is a list of what you’ll need and the approximate costs involved.

    • Mastic: $20 to $25 for a gallon bucket
    • Cheap brush for applying mastic: $1 to $5
    • Tube of mastic caulk: $4 to $6
    • Caulk gun: $8 to $12
    • Mastic tape-10-foot roll: $15 to $20
    • Foil tape – 50-yard roll: $6 to $8
    • Safety eyewear: $4 to $20
    • Safety gloves: $5 t0 15
    • Sturdy 6-foot ladder: $20-40, depending on quality

    Professional Duct Sealing Costs: To hire a professional to apply mastic and foil tape to exposed ducts in your basement and attic, your cost will include the materials and the time it takes.

    • 1,000-1,200 sq. ft. home: 2-3 hours
    • 1,200 – 1,500 sq. ft. home: 3-4 hours
    • 1,500 – 2,000 sq. ft. home, 4-6 hours

    Most HVAC companies are going to price the labor for the job at $60 to $100 per hour, possibly more in areas with a high cost of living.

    Saving Money on Leaky Duct Repair

    The best way to lower your costs, of course, is to do it yourself. Most of the work isn’t difficult to do. If you choose to hire an HVAC company to do the work, be sure to get several estimates so you can get the best deal. Let each contractor know that you’re getting multiple estimates, and they’ll give you their most competitive bid for the job.

    Resources for Repairing Leaky Ducts

    These links take you to pages where you’ll find helpful resources for this house repair project.

    Advantage Home Performance – Here’s a comprehensive article on duct leakage and what can be done about it.

    EnergyStar – This Energy Star page discusses the importance of properly sealing your home’s ducts to prevent energy loss and higher utility bills.

    Bodine Scott Air Conditioning – On this page, you’ll discover five signs your ducts could be leaking including rooms that are cold and poor indoor air quality.

    Mitchell Mechanical – Did you know that leaky ductwork might cause higher HVAC system repair bills? This site shows you how.


Comments are closed.
Back to Top