Why You Shouldn't Use Duct Tape for Ducts

Don’t be fooled by the name. “Duct tape” is great for fixing busted broom handles, patching holes, and holding random things together around the house—it's just not ideal to use on actual ducts. While this multi-purpose tape can do many things, sealing your ducts properly is not one of them. 

Also known as gaffer’s tape, duct tape is incredibly strong and a great binding agent. It originally came to the US during World War II, when the military stocked up on this miraculous tape for emergency repairs on the battlefield.

However, when it comes to the best tape to seal ductwork, duct tape isn’t it. While this may be a sticky subject for many duct tape users, the proof is in the testing. Keep reading to learn why you shouldn’t use duct tape to seal ducts and for advice on better alternatives. 

Duct Tape Isn’t Designed for High Temperatures 

Back in 1998, Berkeley lab tested 19 different sealants, including several types of duct tape, in an accelerated aging test. They alternated air flow between 54 degrees and 167 degrees every five minutes for three months to mimic the changes seen from summer to winter. Of the 19 sealants tested, duct tape was the only product that failed. The extreme temperature changes degraded the adhesive, causing the tape to fail within days, which is not ideal when you consider the temperature extremes that ducts located in your attic or basement are subjected to throughout the summer and winter.

When selecting a tape for sealing ducts, you want one that can withstand temperature changes, especially high temperatures. Duct tape doesn’t cut it.

Duct Tape Doesn’t Seal Properly

The whole purpose of using tape for sealing ducts is to cut back on air leaks, which are notorious for raising your energy bills. If you use duct tape on ducts, the savings will be short-lived because duct tape will eventually fail, and you’ll be dealing with the same leaky ducts. 

When duct tape is consistently exposed to temperatures that are too hot or cold, the adhesive will fail. Once the tape fails, it no longer seals properly, leaving your system vulnerable to more holes and reduced efficiency.

Duct Tape Can Be a Fire Hazard

Duct tape is made of three layers—a top layer of polythene, a middle layer of fabric, and a bottom layer of adhesive. While the polyethylene top layer and the bottom adhesive layer are not flammable, the mesh fabric in the middle layer is.

If something happens to wear away either outer layer, you are left with an exposed middle layer—the flammable material. This creates a fire hazard, and since ducts may be subjected to extreme temperatures, you’ll want to avoid sealing them with anything that might be a fire hazard.

Duct Tape Doesn’t Last Long

If you need to close boxes, fix a broom handle, or temporarily patch a hole, duct tape is great in a pinch. However, it’s not known for its durability.

Since duct tape is vulnerable to extreme temperatures and doesn’t always seal correctly, it should be considered a short-term fix. When it comes to finding tape for sealing ducts, duct tape is not the answer. Instead, you’ll want to use something that will withstand extreme temperatures and last for the long run. 

Duct Tape Can Trap Moisture

For air to flow freely through a duct, it needs to be clear of any debris or blockage. This includes condensation.

While some condensation is okay, a lot will cause issues. Using duct tape to seal ductwork increases the chances of moisture buildup in your ducts. Not only will that keep your ducts from working properly, but it also provides a breeding ground for mold, mildew, and bacteria. Not exactly the types of things you want in your ductwork and distributed throughout your home.

What To Use Instead of Duct Tape

Even though duct tape isn’t the best tape for ducts, you still have a lot of options for properly sealing your ductwork.

Instead of using duct tape for ducts, here are some better options to consider: 

• Duct mastic: Mastic is a gooey material applied with a disposable paintbrush or putty knife. If the gap you are trying to seal in your ductwork is large (greater than a few inches), cover it with fiberglass mesh tape first, then paint over with duct mastic.
• Foil-backed tape: Its ability to withstand extreme temperature changes (especially heat) without shrinking and failing, like cloth-backed duct tape, makes it the best to use when sealing leaks or gaps in heating ducts. The large amount of acrylic and butyl in the adhesive keeps it from drying out and becoming brittle. The foil backing enables it to withstand temperature changes without shrinking and failing like duct tape. Foil-backed tape also allows you to seal gaps without the messiness that comes with using mastic.
• Injected aerosol sealant: Developed at Berkeley Lab’s Environmental Energy Technologies Division, aerosol sealant is a sticky vinyl polymer. It’s ideal for sealing leaks because when it’s pumped into the ducts, it automatically seeks out leaks, spans the hole, and dries, which permanently seals the leak in the process. This product has been extensively tested over a two-year period under various conditions, with no noticeable change in its effectiveness. 

Protect Your Ductwork With Proper Sealing and Repairs!

Duct tape is a wonderful, multi-purpose adhesive that can be useful in every home. However, it does have its limits. Regarding sealing leaks in your ducts, duct tape is not the answer. 

If you suspect an air leak in your ductwork, don’t use duct tape to seal it; call in the pros! The experts at your local Mr. Handyman® have the skills and knowledge to track down duct leaks and repair them properly.

When you need to find a local handyman to help assist with your ductwork repairs and other home maintenance issues, call Mr. Handyman. All of our work is backed by the Neighborly Done Right Promise^™, which means your satisfaction is guaranteed! To learn more or to get started, request service today!