How To Fix Holes In HVAC Ductwork

If you notice decrease heating and cooling efficiency and an increase in energy bills, the ductwork could have a hole. Most ductwork is made from thin sheet metal, which can easily get damaged.

A hole in ductwork may also blow dust, suck hot air into the vents, or blow cool air in unwanted spaces. You should be able to fix the hole in sheet metal ductwork yourself following these tips.

Prepare to Fix the Hole

To fix the hole in ductwork, gather:

  • work gloves
  • safety glasses 
  • marker
  • tape measure
  • rags
  • dish soap
  • pliers
  • putty knife
  • scissors or utility knife
  • aluminum tape approved by Underwriter's Laboratory 181
  • silicone caulk and caulk gun 
  • aviation snips
  • self-tapping sheet metal screws 
  • drill and hex-head screw adapter 
  • 26-gauge sheet metal 

If you don't know what ducts have holes, feel around the ductwork for drafts, kinks, and loose connections, pulling back insulation as needed. You may prefer to mark the holes so that you won't forget the location. Turn off the unit, set the thermostat to low, and let it cool.

Fix Holes with Tape

Smaller holes can commonly be repaired with tape, but do not apply duct tape, since it eventually loosens. Aluminum tape comes in several widths available from home and garden stores but choose the width that will cover the hole. Measure the hole to get the correct dimensions. Mix several drops of dish soap with warm water in a bucket or spray bottle. Moisten a rag in the mixture, clean the hole, rinse, then let it dry. 

If seams have loosened, seal them with foil tape. Unwrap about six inches from the aluminum tape spool, remove the wax adhesive, and start pressing tape several inches over the hole. Unwrap another six inches, overlapping it slightly with the first layer, then make a final pass. Use the putty knife to press the tape in place if needed.

Apply a Sheet Metal Patch

For larger holes, measure the diameter, adding an inch to the width and height. Be aware sheet metal patches have sharp edges, so wear thick gloves. Mark the height and width on the patch, making the line straight by using the blades on the combination square, then cut the patch.

Attach the hex-head screw adapter to the drill, and place the patch in position on the hole, then insert the screws on each corner of the patch. Snip the tip of the caulk tube at a 45-degree angle using scissors or a utility knife, then insert the tube into the gun. Apply an even caulk bead around the patch edges, then let it dry.

For more information, contact your local HVAC repair service today.