Replacing Duct Tape Used on HVAC Ducts

yarrick19

Hello,

I moved into a new house about a year ago that has an unfinished basement. Since the area is unfinished, I can see all the HVAC duct work and I noticed that standard duct tape was used to connect some of the duct work together. I realize this is not the proper tape to use as over time it will not provide an adequate seal and I would like to replace it with the appropriate tape or mastic. I have a few questions about doing this:

1 - Most of the existing duct tape is still sticking fine. Can I just go over the top of it with mastic to seal the joints? Or, do I need to try and remove all the duct tape and then seal with the mastic and or metal tape?

2 - Is mastic enough to seal the joints or do I also need to use metal tape? If its best to use both, do you tape first and then apply mastic over the top or the other way around?

I plan on finishing the basement in the near future so I'd like to get everything nice and sealed before I close it up!

Thanks in advance for all the help.
Paul

JJboy

Yes, do it....

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yarrick19

Thanks for the response... but can someone help answer my specific questions?

Thanks!

TarheelTerp

Mastic is perfect all by itself.

To the largest extent reasonably possible... remove the clothbacked duct tape.
Then put a few extra screws into the joints to stiffen and support.
Then coat everything with mastic. Two coats.

beenthere

Seal all joints you see, both return and supply. then check to see if your air flow decreased. if so. Your return duct is undersized, and the leaks were providing the additional air the system needed. So you'll need to add a return or 2 in that case.

yarrick19

Thanks for the input!