So, you’ve found a leak in your air ducts and being a responsible homeowner; you immediately consider sealing it. Unfortunately, if your first instinct is to reach for a roll of duct tape, you are making a common mistake. Although the name suggests it would be suitable, duct tape is actually one of the most ineffective products to use.
Why Is It Called Duct Tape?
Since you will find rolls of it in home improvement aisles, it is easy to assume that this sticky tape is the right product for sealing a leaky air duct. Unfortunately, the name is quite misleading. According to a report published by Forbes, the tape was developed during the second World War and was originally green and called “duck tape”, The reason behind this name is that the military used the tape to prevent moisture entering ammunition cases. It was quickly discovered that the tape was also very useful for quick repairs. When the housing market boom occurred after the war, the tape became widely available. Some manufacturers changed the product color to silver and marketed it as a method of connecting ducts, changing the name in the process to “duct tape”.
So, Why is Using Duct Tape a Bad Idea?
According to a testing conducted at the Lawrence Berkeley National Laboratory, duct tape was the only product tested that reliably failed. The LBNL experiment was a three month study conducted in 1998 and involved testing over thirty sealant products under typical air duct conditions.
In order to simulate typical conditions, the team forced air at 167ºF and 53.6ºF through several air ducts. Each type of sealant was tested under both hot and cold conditions to see how effective it was at keeping the air contained inside the ductwork. The team also simulated attic heat conditions using a “bake test” where the sample duct joints were baked at up to 187ºF.
The results showed that duct tape allowed either an excessive amount of air to escape, or it would just fall off after only a few weeks. According to Iain Walker, a researcher on the project, the reason for this is that warm temperatures degraded the glue on the tape.
What Product Should You Use?
Instead of using duct tape, the LBNL team recommended sealing ducts with a mastic product. Mastics are sticky sealants that can be painted on and will harden as they dry. While duct tape will initially provide an easy to use short term option, mastics will offer a more long term solution. It is still worth keeping a roll of duct tape in your garage, as it can be an excellent solution for holding two things together. Unfortunately, if you need to seal an air duct, you are not likely to enjoy optimum energy efficiency or comfort if you try to use duct tape.
If you are in doubt about sealing a leaking air duct, it is a good idea to call in an HVAC professional. This will ensure that the duct is properly sealed, and your system will continue to operate at optimum energy efficiency.