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Community and Q&A

Sealing fireplace

bsawers | Posted in Energy Efficiency and Durability on

We will not use the two fireplaces in our house, but we plan to sell in 10 years and the next owners might. We have used plastic sheeting and double-sided tape to seal the openings, but I am looking for something more permanent, but not entirely irreversible.

Is there any reason not to seal the chimney at the top? I know for certain that the furnace and water heater do NOT vent into the chimney.

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  1. Expert Member
    Michael Maines | | #1

    If you seal the top, it's a good idea (and may be required by codes, I'm not sure) to have some sort of note at the fireplace indicating the situation. Even if sealed at the top, warm, moist indoor air will be drawn up the chimney, so it would be a good idea to use a "flue balloon"--a foil balloon made for this situation--with a note attached to a string hanging from the balloon.

    I'm gearing up to seal my three fireplaces once the weather warms up enough to get on the roof. I'll use EPS foam blocks cut smaller than the flue opening and spray-foam them into place.

  2. nynick | | #2

    An operable chimney cap will seal the flue pretty well, while maintaining the ability to use the fireplace whenever. If you want to add the foil balloon as well as Michael has suggested, no harm done.

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