Roof replacement, repair and storm damage in all 4 jurisdictions we cover in St. Clair County, each with its own page: the local permit rule, the code edition it enforces and the building department's number. Of the county's 115,630 homes, 78% were built before 2000 — past the usual 25-year life of a roof — and the median year built is 1975.
Steven Thouvenot, Building Commissioner (618-233-6518 x4265). Also: Scott Tyler, Director of Health, Housing & Building (618-233-6518 x4240); James Broussard, Assistant Building Commissioner (618-233-6518 x4219).
Dan Thomas, Building & Zoning Director (618-722-2207; dthomas@swanseail.org)
618-234-0044
We list a building official's name only where the jurisdiction publishes one — 2 of 4 here do. We list a permit answer only where the jurisdiction states one — 1 of 4 here do, and 1 of those clearly require a permit. Everything else is left blank on purpose.
St. Clair County, town by town
Each line is a summary of that town's own page.
Belleville — 20,212 homes, median built 1962, 26% before 1940; code edition not published; re-roof permit: not published; building official named (Steven Thouvenot).
Fairview Heights — 8,179 homes, median built 1972, 4% before 1940; code edition not published; re-roof permit: not published; no official named.
O'Fallon — 13,530 homes, median built 1997, 5% before 1940; code edition not published; re-roof permit: not published; no official named.
Swansea — 6,175 homes, median built 1993, 5% before 1940; code: 2006 IRC; re-roof permit: yes; building official named (Dan Thomas).
Homes across St. Clair County: the Census numbers
Built before 2000
78%
89,644 homes
Median year built
1975
13% built before 1940
Built 2000 or later
22%
25,986 homes
Owner-occupied
68%
72% detached houses
St. Clair County has 115,630 homes in the Census count, with a median year built of 1975. 13% were built before 1940, 55% before 1980 and 22% in 2000 or later; the single biggest decade was the 2000s, with 16,452 homes (14%). 72% of homes are single-family detached houses and 68% of occupied homes are owner-occupied; the count includes 5,114 mobile homes.
The rule of thumb from Missouri's Department of Commerce and Insurance is a useful life of usually about 25 years for a roof. On that yardstick, 89,644 homes across St. Clair County (78%) were built before 2000 and have outlived at least one roof, and 51,234 (44%) predate 1970. The 16,452 homes from the 2000s are where first replacements are coming up now.
Across the 4 places we cover here with their own Census figures, Belleville has the oldest housing (26% before 1940) and O'Fallon the newest (45% built in 2000 or later). Belleville is the largest, at 20,212 homes, and Belleville has the highest share of renters (40%), where the roof is more often a landlord's decision.
Figures: U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates (tables B25001, B25003, B25024, B25034, B25035). Survey estimates carry margins of error, widest in the smallest places. Census table.
Hail reports in St. Clair County, 2016–2025
NOAA’s Storm Prediction Center logged 50 reports of hail 1 inch or larger in St. Clair County from 2016 through 2025, on 28 days. 11 were 1.75 inches or larger, and 2 of those reached 2 inches; the largest, 2.5 inches, fell on July 17, 2023. The busiest single day was March 14, 2025, with 9 reports.
Year
Reports
2016
4
2017
5
2018
3
2019
6
2020
0
2021
0
2022
2
2023
10
2024
5
2025
15
Counted within 5 miles of each town’s center, Fairview Heights has the most reports (15) and Belleville the fewest (5). Each town’s own page lists its latest dates. Reports come from spotters and the public, so busier places log more of them.
Why the city matters more than the county
Illinois' residential building code covers new construction only, so a re-roof here follows the code each city has adopted for itself. Across the 4 jurisdictions we cover in St. Clair County, that adds up to 1 edition in force:
2006 IRC: Swansea
Belleville, Fairview Heights, O'Fallon publish no edition we could read. Ask before work starts which one the roof will be inspected against.
The design figures are the same across the metro (115 mph ultimate design wind, 20 psf ground snow), so the local difference is the code edition and the permit route. What each figure does to a roof is in our St. Louis roofing code guide.
Common questions about roofing across St. Clair County
Do I need a permit to replace a roof in St. Clair County?
It depends on the city, not the county. Of the 4 jurisdictions we cover across St. Clair County, 1 requires one (Swansea); the other 3 publish no answer either way. Each city page says which applies and links the building department.
Which building codes are in force across St. Clair County?
Across St. Clair County the jurisdictions we cover enforce 1 different edition: the 2006 IRC in Swansea. 3 publish no edition we could read. The edition in force is the one your roof is inspected against.
How old are the houses across St. Clair County?
The Census Bureau's 2020–2024 estimates put the median year built across St. Clair County at 1975, with 13% of its 115,630 homes built before 1940 and 22% in 2000 or later. 78% were built before 2000, so most have had at least one new roof already.
Does a roofer need a license in St. Clair County?
Yes. Illinois licenses roofing contractors statewide under the Roofing Industry Licensing Act (225 ILCS 335), so a roofer working anywhere in the Metro East needs a current IDFPR roofing license. Some cities add their own registration on top; ask the building department.
Which St. Clair County jurisdictions name their building official?
2 of the 4 we cover publish a name: Belleville, Swansea. Where a name is published, it is on that city's page with the department's own number.
Town rules from each jurisdiction's own pages, researched 2026-09-09; housing, Census ACS 2020–2024; hail, NOAA Storm Prediction Center. Sources: data.census.gov · www.spc.noaa.gov · cdb.illinois.gov · cdb.illinois.gov. Rules and staff change; check with the jurisdiction.
Free roof inspection
Roofing anywhere in St. Clair County
Free inspection, a written scope, and photos you keep either way.
