Glacial Lake Hitchcock clay
Lake-bed clay holds water against foundation walls rather than letting it move away. In practice that means seasonal seepage, efflorescence on masonry, sump pumps that run more than their owners expect, and in some cases lateral pressure on foundation walls. It is a well-understood, well-solved problem, but it needs finding, and the fix is grading, gutters, downspout extension, and drainage rather than paint.

