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Community and Q&A

Is it permissible to apply mastic OVER old joint tape?

bHqUcamKme | Posted in Mechanicals on

I have a home with late 1940’s construction. The ducts in the basement ceiling are all sealed with a white tape that is becoming frayed and in poor condition. I’m sure the lack of proper sealing has compromised the system.

I have had varying opinions on whether or not the tape may contain asbestos. I have not had it tested because I’m not sure how I’d go about that.

I’m wondering if I could just coat the tape with mastic, serving both to seal the leaky seams and encapsulating the existing tape if it does contain asbestos.

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  1. Paul McGovern | | #1

    if ducts are leaky & u tape over asbestos tape, where do you think the particles from the continued degradation of the tape might go??? Into conitioned space?
    Why take a chance??/ remove & mastic

  2. davidmeiland | | #2

    It's very easy to get material tested for asbestos, and fairly cheap. Find a lab near you and ask how they want the sample taken and sent. If I recall the last time I did this I paid $45 to have a chunk of old floor tile checked. If it turns out you have something you can decide how to deal with it. Ideally you remove the tape (safely!), clean the metal, apply mesh and mastic.

  3. Anonymous | | #3

    Test it. We had asbestos tape for our cold air return. Easy one days work and they removed it all.

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