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  1. #1
    Join Date
    Aug 2009
    Posts
    3

    Default My plaster walls are growing!!

    Plaster on the chimney(vents the steam boiler and hot water heater 2 floors below) keeps growing a white powdery substance. House is 150 years old walls had always been covered with wall paper, we striped and painted this 2nd floor bedroom about 3 years ago and have had problems ever since. Steps we have taken: bleach, muraitic acid, bulls eye, coated with drywall compound, waterproofing paint... nothing has worked. Things we have changed: repointed chimney above roof and capped chimney. Growth of white powder still forming and is starting on the wall and ceiling on the first floor. Anyone had a similar problem or solution? HELP

  2. #2
    Join Date
    Mar 2009
    Posts
    1,387

    Default Re: My plaster walls are growing!!

    Sounds like you are having moisture in the plaster. have you had a hose test doen to determine if the roofing is leaking around the chimney?

  3. #3
    Join Date
    Aug 2009
    Posts
    3

    Default Re: My plaster walls are growing!!

    We put a new roof on- metal standing seam- with ice guard up 4' as we have built in gutters. Chimney is well flashed and there is no evidence of leaking or moisture around chimney in attic

  4. #4
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,836

    Default Re: My plaster walls are growing!!

    Your chimney was no doubt built for wood or coal and is very large. As the flue gas from the boiler and/or water heater rise they do not produce enoug draft to clear the top of the chiney and it cools and condenses on the chimney wall. Proper sized flues (2) liner for the boiler and water heater should be installed and the rest of the chimney capped.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  5. #5
    Join Date
    Aug 2009
    Location
    Ladson,SC
    Posts
    192

    Default Re: My plaster walls are growing!!

    JLMCDANIEL is correct the boiler venting is the problem.
    The moisture from the boiler is causing the chloride's (SALT) to migrate to the wall surface which will cause plaster failure also the mortar will fail in the structure.

  6. #6
    Join Date
    Aug 2009
    Posts
    3

    Default Re: My plaster walls are growing!!

    Thanks, and 1 correction we did not cap this chimney as it is still be used we did but a cover over it to keep moisture from going down the chimney. It sets about 10" above the chimne. Could this have affected the draft for the boiler? I am meeting with a heating guy this week to discuss a side wall power vent for the boiler.

  7. #7
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,836

    Default Re: My plaster walls are growing!!

    No, the cap is not the problem. Your boiler probably has a flue pipe that is between 3" and 8" in diameter, depending on its age, and you are dumping it into a chimney that is 4 sq. ft. or larger.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

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