Why You're Losing Money - Repairing Large Ductwork Holes
Repairing Large Holes in Your Ductwork
A quick examination of your ducts may lead to some serious surprises. I was amazed to find holes so large that I could put my hand into the ducts. You may also find spots where ducts are completely disconnected. These are huge opportunities to improve the comfort of your home and save a lot of money.
If you find a hole that was cut out for a duct that was never used or any other large hole that size in your ductwork. You'll need to seal it off with another piece of sheet metal. For smaller holes the size of a quarter or smaller you can use fiberglass mesh tape and mastic. I'll describe how to do both.
Repair a Large Hole with Sheet Metal
Repairing a large hole can be easy or hard depending on where the hole is in your ductwork. If it's on the top of ductwork sandwiched in between the floor joists, you're in for a treat. Make sure you clean the ductwork with soap and water or alcohol to make sure the fiberglass tape and the mastic will stick.
Start off by measuring the hole and pay close attention to any obstructions like joists or other ducts that might get in the way.
- Cut a piece of sheet metal with tin snips large enough to cover the hole plus add an extra 3/4" or more on all sides.
- Smear a generous bead of mastic around the hole so the sheet metal can make an air-tight seal.
- Place the sheet metal over the hole and into position.
- Use self tapping sheet metal screws to secure the sheet metal into position.
I was fortunate enough to have an impact driver to get into the tight space between the floor joists. If you have trouble securing it with screws, move on to the next step.
- Cut pieces of fiberglass mesh tape to cover the seams along the outside edge of the sheet metal plate
- Smear another generous amount of mastic over the entire sheet and the ductwork to make sure it is air-tight.
Repairing a Small Hole with Fiberglass Mesh and Mastic
Fixing a quarter sized hole in your ductwork is an easy project you can do in a few minutes. Make sure you clean the ductwork with soap and water or alcohol to make sure the fiberglass tape and the mastic will stick.
- Cut a piece of fiberglass mesh tape about 4" long.
- Stick the tape over the hole.
- Smear or brush a generous coat of mastic over the mesh tape and onto the ductwork. Nickel-thick is the industry standard.
- Check back later to see if you think it needs another coat.