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Community and Q&A

Foil tape inside duct?

runner9 | Posted in Mechanicals on

I have several heat registers that I can access the duct from the inside only on, a few as far as 2 feet into them. Some just have seems, one has a good 1 inch gap on one side. (I’ll try to hammer that together from the inside.)

Anyway, I’ve read that mastic can dry out on the inside of ducts, but have read conflicting suggestions about foil tape. I have this tape right now, should it work on the seems inside the duct, in the last 2 or so feet before the register?

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  1. BobHr | | #1

    I cant tell from the picture but I dont think that is the tape you want. It looks like a roll I bought and wasnt happy with. I buy a tape that can be used in low temps and has a removable layer. It sticks better and it easier to work with. The tape I buy from a HVAC supply house has a thicker more durable foil and better adhesive. I think I pay $13 or so for a roll.

  2. GBA Editor
    Martin Holladay | | #2

    The best quality foil-faced HVAC tapes are the ones with butyl adhesive. Nasha makes one called Nashua 360-17 FoilMastic butyl rubber tape. Here are two links:

  3. runner9 | | #3

    Thank you both. Sounds like you're saying tape on the inside will work, but you don't like the tape I have. I'll investigate the links.

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