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  1. #1
    Join Date
    Nov 2011
    Posts
    5

    Default Sump pump pipe sweating/condensation

    I recently insulated the rim joists in the basement which has made the temperature much more mild. Now that the Wisconsin winter has arrived, the pipe from the sump pump that travels outside is sweating so much that condensation is forming and dripping water onto the floor. There is also frost where the pipe is inserted through the header into the outside (the gap around the pipe through the header has been filled with spray foam).

    My question is...will installing tubular pipe foam insulation stop the pipe from sweating or will the water just accumulate inside?

  2. #2
    Join Date
    Dec 2010
    Location
    Houston Texas
    Posts
    3,179

    Default Re: Sump pump pipe sweating/condensation

    Use the really fat, closed cell black pipe insulation. Its the same as we use for our air conditioner lines in the south.

  3. #3
    Join Date
    Nov 2011
    Posts
    5

    Default Re: Sump pump pipe sweating/condensation

    I'll give that a try. Thank you

  4. #4
    Join Date
    Feb 2016
    Posts
    1

    Default Re: Sump pump pipe sweating/condensation

    Quote Originally Posted by reggietnk View Post
    I'll give that a try. Thank you
    I'm having this issue now, same with living in the upper Midwest and having recently done a much more thorough job of band joist insulation.

    Lots of condensation on the pipes from my sump pumps, and I know what that leads to - water damage and mold.

    Did insulating the pipes work for you?

  5. #5
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,890

    Default Re: Sump pump pipe sweating/condensation

    The condensation/frost is from cold air entering the pipe from the outside. The insulation will protect against this condensation by preventing the warm, moist air from inside the basement contacting the cold part of the pipe.

    In this case, you aren't insulating to keep the pipe cold (or the room warm), but to keep the humid air away from the cold pipe.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

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