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7 Reasons Why Duct Tape Should NEVER Be Used on Ducts

It might have “duct” in the name, but duct tape isn’t code-approved for ducting. HVAC tape uses industrial-strength material designed to withstand heat, pressure, and moisture. Duct tape is not. It is, at most, a temporary “fix”, but it won’t be code-compliant and might cost you extra money.

Duct tape should never be used on ducts because:
  • The heat breaks down the adhesive
  • The cold breaks down the adhesive
  • Condensation can loosen the tape
  • It becomes tedious and expensive to keep replacing the tape
  • You cause more damage with constant duct tape replacement
  • Continued air leaks increase utility bills
  • It is against the building code

1. Heat Breaks Down the Adhesive

Whether your ducting changes temperature because of the surrounding air or as a result of the air going through them, the temperature change negatively impacts the effectiveness of duct tape.

This is not ideal since you are likely trying to correct a problem to prevent the vents from leaking.

Furnace and dryer ductwork gets hot. If the tape is exposed to heated surfaces that are hitting the 140 ℉ range, you will have trouble as the adhesive on the tape begins to soften.

Duct Tape on Dryer Duct | Is It Safe? (What to Use Instead)

The bond to the surface weakens when the glue softens, and the connection becomes less secure. The tape is then unable to hold securely to the ductwork and can start lifting, peeling, and slipping off.

Adhesive on the duct tape softens, the bond to the surface weakens when the glue softens, and the connection becomes less secure

It is also not rated for use on heated surfaces, so you might end up with the tape burning. Tape listed for use on HVAC ducts has a higher temperature rating than duct tape to prevent this.

Another point to note regarding the potential ignition of duct tape under these circumstances is that it can cause the release of toxic chemicals, inhalation of which can cause health problems.

2. Cold Breaks Down the Adhesive

If the ductwork is exposed to very cold temperatures, especially near freezing, this also compromises how well the tape holds.

While the air in your ducts is not likely to be reaching near-freezing temperatures, the ducts often travel through uninsulated regions of the house, which can experience these conditions, making this something that you need to consider.

The glue hardens in this case, losing its stickiness and ability to stay attached to the ducting. Thus, you will find the tape lifting and slipping.

3. Condensation Can Make the Tape Come Loose

Duct tape is water resistant, which helps make it versatile and good for various fixing jobs. However, it is not fully waterproof, and the adhesive is not designed to be in constant contact with moisture.

Duct tape won’t stick properly unless the surface is clean, dry, and even. Water lubricates the adhesive on the tape, causing it to slip as the glue cannot grip the surface firmly.

Where water is present, and the tape comes into constant contact with the moisture, the adhesive will break down. So, if you use duct tape on ducting where condensation forms, the tape will end up peeling off.

On the other hand, if the connection is dry and stays dry, the glue works well.

Causes of Condensation/Sweating

Condensation can form where you need to fix a duct, i.e., where there is a crack or an improperly sealed join. This allows conditioned and unconditioned air (at different temperatures) to mix, resulting in condensation at the opening.

Leaking duct pipe with duct tape on it

Sealing it won’t necessarily be enough to eliminate condensation resulting from the air intermingling. There might still be a slight leak if you can’t cover the whole break or as the tape lifts with heat or cold exposure.

There might also be an insulation problem since duct tape is not the same grade as HVAC materials. Meaning that there might not be sufficient temperature insulation within the ducting.

If the temperature inside the duct is, thus, being influenced by the unconditioned air, it allows condensation to form on the ducts and will result in the tape coming off.

4. Expensive/Tedious to Keep Replacing the Tape

If you are thinking about using duct tape to fix your ductwork in an effort to avoid the cost of expensive repairs, replacements, or call-outs, you should reconsider.

Duct tape can only ever be a temporary solution because it is not designed to work on ducts.

This tape is not registered with the appropriate organizations for use on HVAC ducting since it cannot handle the temperature, moisture, and durability requirements necessary for vents.

That means that any duct tape you use will eventually fail and will keep failing. So, you will have to keep replacing it.

The money you pay to replace the tape and for the energy consumed by damaged and leaking ducts can add up.

Fixing the Duct

It is more economical to pay to repair the duct run properly, with rated materials and even a professional’s help if needed, than to spend months or years attempting to “fix” the ducts regularly.

Plumber inspecting the duct

5. You Can Cause More Damage

You are also risking extra damage to the duct line and your home with the constant repairs.

The more often you must access the vent line, the higher the risk of damaging your ceiling or walls where the line is located or the ducts.

Continuously working on the ducts can also damage them as it increases the likelihood of something getting bent, broken, or disconnected.

6. Continued Air Leaks Increase Utility Bills

Cost of Wasted Energy

The energy you consume and have to pay for increases if you have leaking air ducts.

The reason is that you are paying for energy to condition the air in your home. When your ducts are leaking, some of this conditioned air is escaping and not being channeled to the appropriate rooms and appliances.

Your HVAC system has to work more than it normally would to condition or treat extra air to properly supply your home because of the leakage.

“Duct Tape” Isn’t for Ducts

Despite the name, duct tape is not a solution. It might temporarily stop the air leak, but it will wear down with time or will lift and fall off because of the above reasons. That will leave us back at square one with a leaking duct.

To repair the leak correctly and permanently, you need to use professional-grade materials or may need to replace the duct. You can also hire a professional to achieve a lasting fix, whatever that may be.

7. It Is Against the Building Code (Illegal)

It is pretty confusing that duct tape is not suitable for ducts. It got its name because it was frequently used for repairing and sealing ducts when it was first distributed to the public after World War II. However, that is no longer the case.

Not Approved By IRC

Not only is duct tape not suitable for your ductwork, but using it in your HVAC system is illegal, according to Section M1601.4.1 of the International Residential Code (IRC).

Using DUCT TAPE in your HVAC system is ILLEGAL

The code requires any tape you use on the HVAC ducts to have a specific UL (Underwriters Laboratories) rating, which duct tape doesn’t. This means that duct tape is not approved for this use by the IRC and is not code-compliant.

If you are not code compliant, you can have issues with fines from home inspectors or with insurance claims, and you can have issues when it comes to selling or renting a home out.

In addition, you are extending the problem’s longevity since duct tape won’t fix your duct.

UL Rating

UL is a safety organization that provides safety standards and testing for various household appliances and materials. This includes tapes that you can use to repair and seal ductwork.

The IRC approves of the standards that this company upholds, so they approve of the usage of rated materials provided they have a listing code that matches the purpose you use them for.

HVAC ducting tape must have a listing code of UL 181A.


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