Duct tape seems like one of those things that can be applied universally. However, this isn’t the case, and it is important to know where not to use duct tape. Having this knowledge can save you from increased and unexpected costs and from having a false sense of security about a fix you’ve made.
Duct tape should never be used for:
- HVAC ducts
- Dryer ducts
- Packages for shipping
- Electrical wiring
- Long-term plumbing repairs
- Closing off HVAC vents
- Painted surfaces
- Boat repairs
1. HVAC Ducts
Duct tape should not be used on HVAC ducts because it isn’t code compliant, and even if it were, the tape would not work effectively.
Duct tape doesn’t work well in hot/cold conditions or places where moisture might accumulate. Such conditions break down the adhesive part of the tape and would cause it to not stick where it was placed.
Constant exposure to these conditions could also cause the tape’s structural integrity to be compromised. This would create rips and tears in the tape, as well as overall weakness that reduces the tape’s functionality and/or effectiveness.
HVAC ducts experience such conditions and are, therefore, not a place where duct tape should be used (again, remember that to do so would also be a code violation).
One wouldn’t want tape used on HVAC ducts to fail because leaks in the system could lead to energy loss and poor functioning, which in turn, leads to increased costs.
Additionally, repair failure would be difficult to notice and fix because these ducts are concealed.
2. Dryer Ducts
Dryer ducts and duct tape also don’t mix. This is because it is a code violation to use duct tape on dryer ducts and because of the heat and moisture that could be present on such ducts.
Duct tape that is constantly exposed to heat can have its adhesive dry out. When this happens, the duct tape will no longer stick to the surface to which it was applied.
Moisture further reduces the adhesive’s effectiveness by getting in between the adhesive and the surface it sticks to.
If the tape is exposed to constant or hot enough temperatures, it could also catch fire. This is because the dried tape acts somewhat like kindling.
Tape that fails on a dryer duct will allow air to escape into areas it isn’t meant to be in, which can pose health risks.
This would be especially dangerous if the dryer is a gas dryer because carbon monoxide may be released, which can be fatal if inhaled.
Similar to the HVAC ducts, it would also be difficult to identify and fix tape that has failed if used on dryer ducts.
3. Packages You Are Going to Ship
One reason for this prohibition is that duct tape is too sensitive to water. While it is water-resistant, the adhesive still loses its stickiness if exposed to moisture. If used on a package, and that package gets wet, the package may become unsecured as the tape fails.
Another reason is that the tape has too strong of an adhesive (when functioning properly) for the surface of the cardboard. Any movement of the box can cause the tape to peel off with the topmost layer of cardboard, and the box would be open.
Duct tape also has a difficult time sticking to certain types of cardboard (like corrugated cardboard) in the first place. If the tape is used with a cardboard that it doesn’t adhere well to, then there is another risk of the tape coming unstuck and no longer securing the package.
If you are not going to ship the packages, you will have to weigh the pros and cons to decide if you want to use it for, say, your moving boxes.
4. Electrical Wires
Duct tape shouldn’t be used on electrical wires for a few different reasons.
The first is that the cloth fibers of the duct tape make the fire risk too great.
The cloth fibers are flammable, and when used with electrical wires, which inherently present a risk of fire, that risk is made more relevant and more possible.
Duct tape is also not an easy tape to work with for electrical wiring. From my experience (I remodeled my grandmother’s basement with an uncle after a pipe had burst, which included doing wiring work), working with electrical wiring, there can be a lot of revisions to the work that was done.
This is to say that tape that is applied could very well need to be removed in order to adjust the wire or the location of the tape. Duct tape wouldn’t be good for this because it is difficult to work with once applied, and when removed, it leaves a residue that can ruin the wiring.
Some gas stations carry duct tape for emergency car repairs. However, the stations that carry duct tape should also carry electrical tape because duct tape is not appropriate for fixing any wiring issues you have with your car.
5. Long-Term Plumbing Repairs
Plumbing repairs should never include the use of duct tape. This is because of its closeness to moisture and water. As explained above, moisture and duct tape do not work well together.
Using duct tape for a long-term plumbing repair is essentially guaranteed to fail, which would cause more problems than it had staved off. Using duct tape would just create a false sense of security that pushes the problem later down the road.
This false sense of security brought about by duct tape could also be problematic because the duct tape may have small failures that allow for little leaks that go unnoticed but which, after time, cause serious problems.
The larger the fix, the worse it would be to use duct tape. This is because the problem will resurface and might catch you off guard because you had thought the duct tape would hold and alleviate the problem.
For very short-term plumbing fixes, duct tape could work. But only if, when used, one is aware that the duct tape will not last as a final solution.
Weatherproofing homes by sealing cracks in window frames with duct tape should not be done. This is because the fix would only be temporary, and the tape would struggle with the temperatures and the moisture it would encounter.
If the tape fails, the weather that is trying to be prevented from entering the home will most likely still be able to get in.
This may be another instance of a false sense of security because one might still see the tape where they placed it, but they don’t realize that the tape isn’t working well and is allowing the weather to seep into the home.
Duct tape also leaves a residue behind after being removed. In the case of weatherproofing, unless the weather that is being considered during the application of the tape is constant, it is likely that the tape will be removed at some point. At the very least, to be replaced.
This leftover residue can be difficult to clean off and is very noticeable if the replacement tape doesn’t cover exactly where the prior tape was.
7. Closing off HVAC Vents
First, you shouldn’t even be closing off your vents. This is because closed supply vents increase the amount of air in the ducts, which leads to higher pressure and greater resistance to airflow. The HVAC would then need to work harder to move air.
Closed return vents lower the air volume, which makes it harder for the HVAC to take air to other rooms.
Duct tape used to close the HVAC vents would simply not be effective either. The adhesive would be broken down by the air in the ducts. This would then make the seal no longer effective, and air would still pass through, even if the tape appears to still be on.
If the tape were ever removed, the leftover residue would also trap dust.
This would make reapplying the tape less effective because the trapped dust would then get attached to the new piece of tape and make its adhesive less effective. It also doesn’t look great.
8. Painted Surfaces
Duct tape should not be used on painted surfaces. Duct tape can peel off the paint beneath it when removed.
Duct tape also could lose its stickiness if painted over, and paint could seep beneath the tape. This is to say that it shouldn’t be used in place of painter’s tape, either.
Duct tape is designed to be a relatively permanent bond, and as such, it is very sticky. This is what gives it the potential to peel paint from whatever it is stuck to.
Depending on the strength of the wall itself, duct tape could actually damage the wall.
Painter’s tape, on the other hand, is meant to be temporary, so its adhesive isn’t as strong, and as such, it won’t peel paint off of the surface it is on.
The sticky residue left by duct tape is another reason why it shouldn’t be used on painted surfaces. The sticky residue will trap dust and other debris, which may not provide an aesthetically pleasing look to whatever the tape had been used on.
9. Boat Repairs
From the above cases, it should be clear that duct tape shouldn’t be used for boat repairs. Boats are guaranteed to experience moisture (unless you’re repairing a boat that won’t be taken out on the water!).
The guarantee of encountering moisture ensures that the repair will eventually fail. The time frame of that failure just depends on where the tape is used on the boat.
If the tape is used on the outside of the boat and on a spot that is below the water level, the tape might as well just be thrown in the trash.
If the tape is used inside the boat, it might last longer. But even the inside of a boat will get wet at some point or be subject to some type of moisture.
The duct tape could also strip the paint from the places it is used on the boat. The leftover residue is another reason not to use duct tape to repair a boat, especially if the repair is inside the boat.