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Q&A Spotlight

Water Damage in Brick Basement

Seasoned builders and a moisture expert debate whether rising damp or a blocked chimney caused this brick column to crumble.

What's eatin' this brick? Some say it was a salt lick for some subterranean farm animals, but the consensus seems to be efflorescence from rising damp.

In a recent discussion from our Q&A forum, Chris Ermides tries to determine what caused severe deterioration of a brick column in the basement of his Victorian home. Chris knows that his basement could use some moisture remediation, but he is puzzled that none of the nearby brick walls have similar signs of decay. Fortunately, the chimney that the column once supported is long gone, and the load of the adjacent beams rests comfortably on lally columns, but Chris is still determined to solve this mystery.

Michael Maines tells Chris that either basement-dwelling livestock used the efflorescing minerals in the column as a salt lick (JK), or we’re seeing a phenomenon called “rising damp.” The whitewash on the bricks above is actually one way of dealing with it.

Michael Chandler thinks the water that caused the spalling may have entered through the old chimney due to a poorly maintained cap. Michael suggests that the epicenter of the damage may be where the bottom flue tile, or some other obstruction, held the water until it worked its way through the brick.

James Morgan doubts that rising damp would occur so high above the ground (especially since the foundation walls don’t show similar deterioration). He agrees with Michael Chandler that water trapped in the old chimney may have been the culprit — possibly from a blocked ash cleanout that has since been filled in. James goes out on a limb to suggest a third scenario: perhaps someone started to demolish the old chimney base but had second thoughts.

I also pointed Chris to Joe Lstiburek’s recent Building Science podcast on efflorescence.


Green Building Advisor’s Technical Director, Peter Yost, went to the rising damp master, BIll Rose, to try to solve this once…

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  1. Harry Applin | | #1

    There isn't a lot of info here, but if the Victorian is in a northern climate it is possible that wicking is drawing moisture up the brick and then a light freeze is happening which is slow breaking the brick and concrete. Since cold air settles at a low spot it could explain the level. The walls would not see the problem because the earth behind them and the ground beneath the column is transferring warmth up the column. Just speculation without more info.

  2. David Murrah | | #2

    What is really intertesting here ...
    The most interesting and amusing aspect of these questions posed by GBA, is how many people are willing to venture a guess or even a professional opinion with so little information. Rather than speculation, how about questions? I wonder if medical websites post pictures of sick patients with descriptions like, "feels bad," and expect to get a diagnosis. Many comments should lead to a list of questions, not possibilities.
    - How long have you lived in the house, where is it, what are the typical soil conditions?
    - Does this appear to be a column or a chimney?
    - What is the current condition of the brick (including above and below), is it still deteriorating?
    - Do any neighbors have similar issues?
    - What does the salt taste like? (OK, that's my joke)
    - etc, etc.

    When I take my car to a mechanic and after a brief description of the problem, he claims to know exactly what the problem is, I get a little worried. Don't be that guy.

  3. GBA Editor
    Rob Wotzak | | #3

    Did you take a look at the original Q&A?
    You've got a good point. Maybe I should have pulled a little more of the conversation form the original Q&A post into this blog entry to show readers that there actually was a fair amount of questioning going on--not just hypothesizing. These Q&A spotlights are just a way of highlighting interesting problems that haven't necessarily been resolved. I don't think that any of the opinions from the forum were stated in a way that said, "ah, that's the answer!" That said, I'm glad there are readers out there trying to keep us honest. I appreciate that it's the collective knowledge of this community that can ultimately help us all build better homes.
    Rob Wotzak

  4. Dave | | #4

    Is there a clean out?
    I have seen this happen when the chimney clean out hasn't been cleaned out. The level of ash and dirt becomes several feet high. Then rain water dropping through from the top of the chimney ends up working its way out of the brick wall at a level above the floor.

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