Basement Water Damage in a Lincoln Park Two-Flat

Published January 4, 2025 by Mike Torres

Chicago, IL

Illinois landscape

I bought the two-flat in Lincoln Park in 2019. One of those classic Chicago buildings with a finished basement that previous owners had converted into a rec room sometime in the 1990s. The real estate listing called it "bonus living space." What they should have called it was "future water damage."

The first two years were fine. Then came April 2021. We got four inches of rain over three days while the ground was still partially frozen from a late cold snap. The combination overwhelmed the city's storm drains, and water found its way into basements across the North Side, mine included.

I came downstairs to find an inch of water across the floor and the bottom foot of drywall already soaked.

What Happened

Chicago's aging sewer system can't always handle heavy spring rains, especially when the ground is still semi-frozen and can't absorb runoff. Water backs up, the water table rises, and basements flood. It's common enough that most Chicago homeowners have flood stories.

My basement had two problems working together. First, cracks in the foundation from years of freeze-thaw cycles had created entry points for groundwater. Second, the previous owner's drywall job hadn't included any vapor barrier, so moisture had been wicking through the concrete for years. The flood just accelerated existing damage.

The Damage Assessment

I called a restoration company the morning after. They confirmed what I suspected: the drywall was saturated and had to come out. But they also found mold behind the walls, black and fuzzy growth that had been developing for who knows how long, probably since before I owned the place.

The estimate was ugly. Mold remediation: $3,200. Drywall removal and replacement: $2,800. Foundation crack repair and interior waterproofing: $4,500. We're talking over $10,000 total. I ended up doing the drywall work myself and hiring out the mold and waterproofing, which brought the total to about $6,800.

The Repair Process

The mold company removed all affected drywall plus an extra 18 inches above the water line. They treated the foundation walls with antimicrobial solution and set up drying equipment for a week. Once they cleared the space, a different contractor came in to repair foundation cracks and apply an interior waterproofing membrane.

I waited another week after waterproofing before putting up new drywall. This time I did it right: moisture-resistant drywall with a vapor barrier behind it, and I left a half-inch gap at the floor so any future water wouldn't wick up into the walls.

Lessons for Chicago Homeowners

Every Chicago basement has moisture potential. The freeze-thaw cycles, the aging infrastructure, the clay soil, the high water table in many neighborhoods, they all conspire against finished basement spaces. If you're buying a place with a finished basement, look closely at those walls. If you're finishing a basement, invest in proper waterproofing first.

My basement looks great now, but I check it after every heavy rain. Some paranoia is warranted when you live in a city built on a swamp.