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  1. #1
    Join Date
    Apr 2011
    Posts
    2

    Exclamation Horsehair plaster on chimney -safe?

    I am planning to have a wood stove installed into an old chimney. It will have a new insulated flue liner, backer board behind the stove, etc. but I removed the panelling that covers the chimney now because I was going to remove the panels to leave the chimney exposed and discovered that it is covered with ugly old horsehair plaster. I don't know if the chimney was operated like this or how long it has been there. What I want to know, before I build a hearth for the stove, is if this will be safe in terms of fire resistance and possible fumes? Thank you.

  2. #2
    Join Date
    Aug 2009
    Location
    Ladson,SC
    Posts
    192

    Default Re: Horsehair plaster on chimney -safe?

    As for fire rating the plaster will not burn and would be rated the same as the substrate it is applied to.
    As for Fumes there would be none from the plaster.
    In high heat the lime will return to a powder, sand will melt and the hair will burn.
    If this plaster has any Gypsum content it may have some rating?

  3. #3
    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    975

    Default Re: Horsehair plaster on chimney -safe?

    I have seen such plastered chimneys survive house fires intact. The quantity of animal hair used in lime plaster scratchcoat/browncoat is inconsequential in terms of incurring a fire hazard.
    Nor does plaster give off fumes of any kind. It is a sanitary material, unlike drywall or wood.
    Casey
    Remove not the ancient landmark, which your fathers have set.

  4. #4
    Join Date
    Sep 2009
    Location
    florida
    Posts
    598

    Default Re: Horsehair plaster on chimney -safe?

    Hmmm....Ive never heard of Horse Hair plaster so I googled it. It looks like some of it has Asbestos mixed in with it.

    You might want to research it some.....

    Good Luck
    Gizmo

    Cut it 3 times & it's still to short.
    Inventor of the Miter Master Plus.

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  5. #5
    Join Date
    Apr 2011
    Posts
    2

    Default Re: Horsehair plaster on chimney -safe?

    Thank you very much for the insight. I think I will remove the "Wood" panels and install cement board and tiles over the chimney just for aesthetic reasons and in an abundance of caution.

  6. #6
    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    975

    Default Re: Horsehair plaster on chimney -safe?

    Only three things must be in lime plaster: hydrated lime, sand, and water; animal fibers were added to minimize drying cracks and help the lath keys stay strong; anything else added, like asbestos, was just an adulteration/unnecessary.
    Casey
    Remove not the ancient landmark, which your fathers have set.

  7. #7
    Join Date
    Apr 2011
    Posts
    1

    Default Re: Horsehair plaster on chimney -safe?

    On this same note, I'm in Va. where historical homes sometimes have plastered fireboxes in the fireplaces, to protect the bricks before the days of special firebrick, I understand. Anybody know when this practice was discontinued and how common it was? My old house is from 1860 and I'm considering the same idea. At this point, there is no evidence that the fireboxes were plastered originally. In This Old House, I'd like to see more articles on restoration, instead of renovation.

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