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Basement Risk Index™ · Community Report

Basement Flood Risk in South Lyon, Michigan

South Lyon’s Basement Risk Index is 10/100 (LOWER). 10% of homes here were built before 1960 (U.S. Census ACS 2020-2024, updated Jul 2026), the biggest driver of basement-flooding risk in this region.

10BRI / 100
LOWER RISK
Ranked #105 of 116 metro Detroit communities

Data confidence: C, modeled from housing-age measures; no local flood records integrated yet. How the score is built →

South Lyon, Michigan carries a Basement Risk Index of 10 out of 100, ranking #105 of 116 metro Detroit communities, far below the metro median of 37. South Lyon is one of the metro's newer communities, its housing peaking in the nineteen-nineties, well into the era of modern basement waterproofing, the main reason its Index sits toward the lower end of the range. Among South Lyon and its five nearest neighbors it carries a middle-of-the-pack modeled risk; its housing is mostly owner-occupied and middle-income for the region.

Water in your basement in South Lyon right now?

  1. Don’t enter standing water if the power is on. Cut it at the breaker only from a dry spot, or call an electrician.
  2. Photograph and video everything before you move or clean up anything, insurance and city claims both turn on this.
  3. Michigan law gives you about 45 days from discovery to file a written damage claim with your sewer authority. Start today.
  4. Once it is safe, call a licensed waterproofing contractor. Do not wait for it to dry on its own.

South Lyon basement risk at a glance

Basement Risk Index10 / 100 (LOWER)
Metro rank#105 of 116
Homes built before 196010%
Peak building era1990s (32% of homes)
Median year built1991
Median home value$294,600
Median household income$92,467
Owner-occupied81%
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

South Lyon's housing is concentrated in a single era, peaking in the nineteen-nineties at about 32% of today's homes; relatively few of the stock, 10%, predates 1960. These are mid-range homes for the metro, and 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 clay drain tiles.

2020 or later
1%
2010s
4%
2000s
15%
1990s
32%
1980s
11%
1970s
19%
1960s
7%
1950s
5%
1940s
1%
Before 1940
4%

How basement risk varies inside South Lyon

We score 3 individual neighborhoods inside South Lyon, and the pattern is skewed to the lower bands: 0 fall in the high or very high band, 0 are elevated, and 3 are moderate or lower. The number that matters is the one for your own block, not the city average.

0Very High
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. Among its immediate neighbors, South Lyon scores higher than Lyon Township, so the block next door is a better guide than any metro-wide average.

Why South Lyon homes face basement risk

Basement risk in South Lyon comes down to two things: how old its houses are and the clay beneath them. With relatively few of its homes, 10%, built before 1960 and the biggest share going up in the nineteen-nineties, many sit on original clay drain tile, and southeast Michigan's dense clay holds water against those foundations rather than letting it drain.

How South Lyon compares

South Lyon's Index of 10 ranks #105 of 116 communities region-wide and sits below the metro Detroit median of 37. It runs higher than its nearby neighbor Novi.

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 sewer backup 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.

Hiring in South Lyon?

We keep public-record profiles of metro Detroit basement waterproofing contractors, drawn from their own listings and Michigan licensing records. No ratings and no pay-to-play, just the record. Browse the contractor records →

Public records of contractors whose own listings say they serve or are based in South Lyon: Michigan Basements.

See South Lyon on the full metro Detroit Basement Risk Index map →

Concerned about this score?

We connect South Lyon homeowners with one licensed, insured basement waterproofing contractor for a free, no-obligation assessment. Your information goes to one local pro, never to lead lists.

Request your free assessment →

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

Nearby communities

Lyon Township · 1Novi · 5Milford Township · 20Northville · 43Wixom · 12

Homeowner guides

Does insurance cover sewer backup?What to do when your basement floodsWhat waterproofing costs in metro DetroitHow to choose a waterproofing contractorSump pump costs in MichiganBackwater valves: cost and who needs oneThe 2021 metro Detroit floodsWhat keeps a Michigan basement dry

Frequently asked questions

Where does South Lyon rank for basement-flood risk among nearby communities like Lyon Township and Novi?

South Lyon scores 10 out of 100, ranking #105 of 116 metro Detroit communities (LOWER risk). Among its five nearest neighbors it carries a middle-of-the-pack risk: Lyon Township scores 1 and Novi scores 5.

Are South Lyon's homes older than those in nearby Lyon Township and Novi?

10% of South Lyon homes were built before 1960 (median year built 1991, with the largest share in the nineteen-nineties). In Lyon Township, 7% predate 1960 (median year built 2003). Older housing means more basements plumbed before sump pumps, weeping tile, and backwater valves were standard.

What is the biggest basement-flood driver in South Lyon versus Novi?

Housing age and clay soil. 10% of South Lyon homes predate 1960, and southeast Michigan's dense clay holds water against older foundations rather than draining it. South Lyon scores 10 and Novi 5, so the same prevention steps apply, sized to each home.