Duct Tape Isn't For Ducts

Anyone who has seen the Red Green show knows handyman Red can do just about anything with a roll of duct tape. In the spirit of TV humor, Red does lots of things with duct tape that make no sense and just shouldn’t be done that way. Using duct tape to seal duct work is one of those.

Big Energy Waster

Air leaking from ductwork can be the biggest energy-waster in a home. That is especially true if the ducts are located in unconditioned spaces such as attics and crawlspaces. Even if ducts are located in a basement or conditioned area of the home, duct leakage can keep heated or cooled air from being distributed to the rooms where you want it.

Seal Ducts During Installation

Older ducts and even brand-new ducts leak if they are not air sealed at the time they are installed. Installing ductwork means joining lots of sheet metal to include the seams between the sections, along the sections, at boots, registers and takeoffs.   Air leaks occur all along the length of the ductwork.

The fix, of course is to stop the leakage.  That much is obvious.  The question is, how to seal the leaks?  The temptation is all too easy to reach for that ubiquitous roll of duct tape.  Everyone seems to have a roll or two around the house.  It is great for all kind of things.

Why Not Duct Tape?

Duct tape is just a temporary fix to seal ductwork.  When it first goes on, if it is applied meticulously and thoroughly, it will seal the leaks.  Then, it will deteriorate over time.  Duct tape does not expand and contract with heat.  As the ductwork expands and contracts with the flow of heat, the duct tape will be repeatedly stretched and relaxed until it literally falls apart.  In the process, the tape and its adhesive will dry out and the tape will lose its air seal.

Mastic is Far Superior 

The material to use for sealing ducts is called mastic.  Mastic comes in tubs, is thick, and is applied to the seams of ductwork with a narrow paint brush or knife.  The mastic is spread in a thick layer (not like paint) and seals the leaks.  It takes about 24 hours to set and once it does, mastic expands and contracts with heat, right along with the duct work itself.  This allows mastic to last for many years and maintain a tight air seal.

By the way, you probably have at least a few hundred feet of ductwork in your home once you add up all the main trunk lines, supply runs and return runs.  How long do you think it would take you to duct tape them?  How long to seal them with mastic?  You would be amazed at how many hours it takes.  If you are doing it with a friend, plan for a two-day weekend.

Sealing ductwork with mastic is a job you do once and it is done forever.  Just don’t tell Red Green.

Contact Dr. Energy Saver today for your free estimate for duct sealing and our other energy saving services such as home insulation and our home energy audit.