Much of Madison sits between two lakes on filled marsh, with a water table close to the surface. Wet, silty glacier soil freezes several feet deep each winter and pushes on basement walls, and many homes near the isthmus and campus have stone or block basements close to 100 years old.
Not every crack is a problem
Almost every Madison basement has a crack or a damp spot somewhere. Most are nothing to worry about. A few are early signs of a wall that is moving or water that is getting in. This page helps you tell them apart.
When in doubt, the free inspection is the easiest way to know for sure.
Signs to have checked soon
These are the signs most likely to mean a wall is moving or a real water problem.
A long sideways crack across a block wall. It usually runs along a mortar line a few rows down from the top. This is the classic sign of a wall being pushed in by frost and wet soil.
A wall that bows or leans in. Look down the wall from one end. If the middle bulges toward you, or the top has slid in past the bottom, it is moving.
Stair-step cracks at the corners of a block wall. Cracks that zig-zag along the mortar often mean pressure or settling.
A crack where one side sticks out past the other. The wall has shifted.
Water at the joint where the wall meets the floor. This is ground water pushing up and in. In Madison, it is often worst in spring and after wet years.
An old stone wall that bulges, or mortar that falls out in chunks. The Wisconsin Historical Society says old stone walls can bow inward from water and tree roots.
Cracks that grow. Any crack that is longer or wider than it was last season.
Signs upstairs
Foundation movement often shows up in the house above.
Doors that stick all year, not just in summer.
Cracks over door and window frames that come back after patching.
Floors that slope or dip, often in an addition or over a crawl space.
Gaps where walls meet the ceiling or floor.
A chimney or porch pulling away from the house.
Signs of water
Water problems are the most common call in Madison, and they lead to wall problems over time.
A wet line along the bottom of the wall after rain.
Water in the basement during snowmelt.
White powder on the walls. This is salt left behind by water passing through.
A musty smell, or mold on stored boxes.
Paint or coating peeling off the walls.
A sump pump that runs all the time or a pit that is always full.
Window wells that fill with water.
Signs that are usually cosmetic
Thin, straight up-and-down cracks in a poured wall that do not leak or grow.
Small cracks in a basement floor with no water or lifting.
Doors that stick only in humid summer weather.
Small drywall cracks at the corners of doors that do not come back after patching.
Keep an eye on these. Mark the ends of a crack with a pencil and the date, and check again after the next freeze or big rain.
A quick check each season
Twice a year, walk your basement with a flashlight. Spring, after the snow melts, and fall, before the ground freezes, are the best times in Madison.
Look along the bottom of every wall for damp lines or white powder.
Check each crack you marked last time. Has it grown?
Sight down each block wall for a bow.
Make sure the sump pump turns on when you lift the float.
Walk outside and check that downspouts drain several feet from the house.
Why Madison homes show these signs
Madison has a high water table near the lakes and on the isthmus, where much of the city was built on filled wetlands. City staff say ground water flooding there hits older homes hardest after many wet seasons. Add deep frost each winter, and basement walls take a push every year. About 1 in 8 Madison homes was built in 1939 or earlier, and those old stone and block walls show the signs first.
A note on radon
Public Health Madison and Dane County reports that about half of homes tested in the county had high radon. Radon can come in through small cracks in floors and walls. If you have cracks, a radon test is cheap and worth doing.
Frequently asked questions
What is the first sign of foundation trouble in a Madison home?
Most often it is in the basement. A damp line at the bottom of a wall, a crack that leaks in spring, or a long sideways crack in a block wall. Upstairs signs like sticking doors usually come later.
Are hairline cracks in a poured basement wall normal?
Yes, mostly. Concrete shrinks as it cures, and thin up-and-down cracks are common. Watch them. If they leak, grow or one side sticks out past the other, have them checked.
Is white powder on my basement wall a problem?
It is called efflorescence. It is salt left behind when water passes through the wall and dries. It is not dangerous, but it tells you water is moving through the wall.
Do sticking doors always mean foundation problems?
No. Humid Madison summers swell wood doors, and they often loosen up again in winter. A door that sticks all year, along with a crack over the frame, is more likely a sign of movement.
When should I call right away?
Call now if a wall is bowing more than a little, if a crack is growing fast, if water is coming in during every rain, or if a door or window suddenly stops working. These usually get worse with the next freeze or storm.
Can I check my wall for bowing myself?
Yes. Hold a long level or stretch a string tight from the top of the wall to the bottom. If the middle of the wall touches the level or string while the top and bottom do not, the wall is bowing in.
Not sure? Get a free look
You do not have to guess. Call (608) 719-3321 or send the short form, and a local crew will call you back, usually the same day. They will tell you which signs matter and what, if anything, needs fixing. The inspection is free.