Cut too big of hole in main duct...

[RyanB]

I screwed up, I am doing a heat run in the basement and cut the hole too big in the main duct. My hole is about 7.5-8" and I need a 7" hole. It is in a hard to reach area that really sucked cutting. What would be the best thing to do here? I was going to put it in anyway and heavily tape around it but a friend mentioned something about cutting a piece of sheet metal to put over it and cutting a 7" hole in that. What do you think? If I did that, what is the best way to attach the sheet metal to the duct? Screws?
Please help, I am a rookie at doing this! Thanks!

[notuboo]

I'd put an oversized piece of sheet metal in place with the hole cut as needed.

I'd run some silicone caulk around the outside edge and secure in place with self tapping tek screws.

Just a thought, which you had already expressed to a certain extent.
Good luck...

[Ed Imeduc]

Like said get a bigger piece of sheet metal to cover the hole about 2" all around. Cut and put in it the new takeoff. put it up on the duct with 1/2"X#8 sheet metal screws. just use the aluminum tape all around. Not just duct tape or caulk

ED ;)