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Basement Risk Index™ · Community Report

Basement Flood Risk in South Lyon, Michigan

8BRI / 100
LOWER RISK
Ranked #104 of 116 metro Detroit communities

South Lyon, Michigan carries a Basement Risk Index of 8 out of 100, ranking #104 of 116 communities across metro Detroit, which is below the metro Detroit average. The score is driven by housing age and soil: 11% of South Lyon homes were built before 1960, the era before sump pumps, exterior weeping tile, and backwater valves were standard, and the region's heavy clay soil holds water against those older foundations.

South Lyon basement risk at a glance

Basement Risk Index8 / 100 (LOWER)
Metro rank#104 of 116
Homes built before 196011%
Peak building era1990s (34% of homes)
Median year built1991
Median home value$249,800
Median household income$82,753
Owner-occupied83%
Neighborhoods analyzed3

South Lyon's score is modeled from U.S. Census housing data; no municipal flood records are integrated yet. The Basement Risk Index is built from U.S. Census housing data and documented flood records. See our full methodology.

When South Lyon was built

The housing stock in South Lyon peaked in the 1990s, when about 34% of today's homes were built. In total, 11% of South Lyon homes predate 1960. That matters because basements built before the 1960s typically lack the sump pumps, perimeter drain tile, and backwater valves that became standard later, leaving many on their original, aging clay drain tiles.

2020 or later
0%
2010s
2%
2000s
16%
1990s
34%
1980s
13%
1970s
17%
1960s
7%
1950s
4%
1940s
2%
Before 1940
5%

How basement risk varies inside South Lyon

We score 3 individual neighborhoods inside South Lyon. Of those, 0 fall in the high or severe band, 0 are elevated, and 3 are moderate or lower. Risk is rarely uniform across a city, so the most useful number is the one for your own block.

0Severe
0High
0Elevated
0Moderate
3Lower

What this means for South Lyon homeowners

South Lyon scores toward the lower end of the metro range, largely because of its newer housing. Risk is still real on clay soil, so watch for symptoms after heavy rain.

Why South Lyon homes face basement risk

Basement flooding in South Lyon is mostly a function of housing age and soil. Older homes were built with clay drain tiles that crack and clog over decades, and the dense clay across southeast Michigan holds water against foundations rather than letting it drain.

How South Lyon compares

South Lyon's Index of 8 is below the metro Detroit median of 36. It ranks #104 of 116 communities region-wide.

Does insurance cover it?

Often not. Standard Michigan homeowners policies commonly exclude sewer backup and groundwater unless you carry a specific endorsement. Before the next storm, it is worth reading our guide on whether insurance covers basement flooding in Michigan and checking your declarations page.

What to do about it

  1. Lower risk is not zero risk on the region's clay soil, a free prevention check takes about 30 minutes.
  2. Watch for symptoms after storms; what you see at your own home matters more than any average.
  3. Maintain gutters and grading, the two cheapest protections any Michigan home has.
See South Lyon on the full metro Detroit Basement Risk Index map →

Explore the data behind this score

Basement Risk Check is a free, public homeowner resource built on public records. No signup, no login.

See South Lyon on the interactive metro Detroit Basement Risk Index map →
Read the published methodology →
Browse all 116 communities ranked →

Nearby communities

Lyon Township · 2Novi · 3Milford Township · 15Northville · 69Wixom · 9

Homeowner guides

Does insurance cover basement flooding?What to do when your basement floodsThe 2021 metro Detroit floodsWhat keeps a Michigan basement dry

Frequently asked questions

Is South Lyon at high risk for basement flooding?

South Lyon scores 8 out of 100 on the Basement Risk Index, ranking #104 of 116 metro Detroit communities (LOWER risk). The score reflects how much of the local housing stock predates modern basement drainage, on the region's clay soil.

Why does housing age matter so much in South Lyon?

Sump pumps, exterior weeping tile, and backwater valves only became standard in the 1960s and 70s. 11% of South Lyon homes were built before 1960, with the largest share built in the 1990s. Many still rely on original clay drain tiles that fail over time.

Does homeowners insurance cover basement flooding?

Often not. Standard policies commonly exclude groundwater and sewer backup unless you carry a specific rider. See our Michigan insurance guide.

Is this resource free to use?

Yes. The Basement Risk Index and every community report are free and public, with no signup and no login.