Mine has begun to crack so I want to give it another once over coat and also silver coat it - is the stuff they use Karnak 19 Flashing Cement or something else?

Chimney flashing

  • Another coat might bring the place down. Looks like a thousand pounds on there already. I'd consider stripping it at some point and starting fresh. Eventually it's so big and unwieldy that you can't reliably reseal it due to thermal expansion.
    – isherwood
    Commented Aug 9, 2023 at 15:02
  • I seriously doubt that the entire city uses the same product. Looks like some sort of tar coating. Which, precisely, is unknowable without some sort of forensic science analysis that's not cost effective.
    – Ecnerwal
    Commented Aug 9, 2023 at 18:46
  • every roof I've ever been on in New York City seems to have chimneys with what looks to be same coating - so it seems to be a common practice - not sure how many varieties of coatings there are that all look like this. Commented Aug 9, 2023 at 19:43
  • It would seem you should be asking this of the people who's NYC roofs you have been on.
    – RMDman
    Commented Aug 10, 2023 at 0:50
  • @RMDman not possible since they don't know (most people rent) Commented Aug 10, 2023 at 11:51


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