"Waterproofing" covers a range of fixes that do very different jobs at very different prices. Here is what each one actually does, roughly what to expect, and the order most Michigan homeowners should think about them.
The cheap fixes that prevent the most problems
Gutters and downspout extensions
The single cheapest protection there is. Clogged gutters and downspouts that dump water right at the foundation are a leading cause of basement moisture. Extending downspouts at least six feet from the house moves thousands of gallons a year away from your walls. Cost: very low.
Grading
The soil around your foundation should slope away from the house, not toward it. Regrading or building up low spots is inexpensive relative to its impact. Cost: low to moderate.
The mechanical systems
Sump pump (and a battery backup)
A sump pump sits in a pit at the low point of your basement and pumps incoming water out before it floods the floor. It is essential equipment for most metro Detroit homes. The most common failure point is a power outage during the exact storm you need it, which is why a battery backup is one of the highest-value upgrades you can make. Cost: moderate.
Backwater valve
A backwater valve installs on your main sewer line and closes automatically if the municipal sewer backs up, stopping sewage from pushing into your basement. For older homes on combined sewers, this is the fix that addresses the 2021-style disaster. Cost: moderate.
The bigger drainage systems
Interior weeping tile (drain tile)
A perforated pipe installed inside the perimeter of the basement floor collects water that reaches the footing and routes it to the sump. This is the workhorse of interior waterproofing for chronic seepage. Cost: higher; it is an installed system.
Exterior waterproofing and excavation
The most thorough and most expensive option: excavating around the foundation to seal the walls and install exterior drainage. Reserved for serious, persistent problems. Cost: highest, often five figures.
Match the fix to your actual risk
The right system depends on how water is getting into your specific basement, which depends a lot on your home's age, your soil, and your sewer connection. Start by checking your neighborhood's Basement Risk Index, then have a licensed local contractor confirm what your home needs.