Attic insulation, air sealing and crawl space work across Madison County. We cover 5 jurisdictions here, each with its own page: the energy code that applies, the attic R-value it requires, the permit position and the building department's number. Of the county's 119,168 homes, 15% were built before 1940, and 32% of occupied homes heat with electricity.
Click a city for its full code, permit and rebate detail.
| City | Energy code | Attic R required | Permit to insulate | Building dept. |
|---|---|---|---|---|
| Alton | Illinois state code | R-49 | Not published | 618-463-3500 |
| Collinsville | Illinois state code | R-49 | Not published | 618-346-5200 |
| Edwardsville | Illinois state code | R-49 | Not published | 618-692-7535 |
| Glen Carbon | Illinois state code | R-49 | Not published | 618-288-2615 |
| Granite City | Illinois state code | R-49 | Not published | 618-452-6218 |
All 5 publish an energy code edition we could name and all 5 a required R-value we could read; a blank in this table means the jurisdiction publishes nothing, not that we guessed.
Illinois writes one residential energy code for the whole state, and under 20 ILCS 3125 a town may make it neither weaker nor stronger, so the attic figure for new work is R-49 in every one of the 5 places we cover in Madison County. What changes from town to town is the permit desk.
Here, Granite City requires contractors to register. The town pages carry each department's number.
The 5 places here with their own Census row hold 53,665 of Madison County's 119,168 homes (45%); the rest are in other municipalities or unincorporated areas.
One detail worth knowing before a job in each of them:
Madison County has 119,168 homes in the Census count, with a median year built of 1971. 61% were built before 1980 and 19% in 2000 or later; the single biggest decade was the years before 1940, with 17,395 homes (15%). Of 110,134 occupied homes, 61% heat with utility gas and 32% with electricity.
Across the 5 places we cover here, Alton has the oldest housing (28% before 1940) and Edwardsville the newest (27% built in 2000 or later). Granite City is the largest, at 12,854 homes, and Glen Carbon has the most electric heat (42%).
| Place | Homes | Before 1940 | Median built | Electric heat | Owner-occupied |
|---|---|---|---|---|---|
| Granite City | 12,854 | 23% | 1957 | 28% | 73% |
| Alton | 12,551 | 28% | 1953 | 36% | 60% |
| Collinsville | 11,644 | 17% | 1971 | 37% | 66% |
| Edwardsville | 10,609 | 16% | 1986 | 39% | 67% |
| Glen Carbon | 6,007 | 5% | 1990 | 42% | 69% |
Against the eight-county metro on this site (1,177,290 homes), Madison County's pre-1940 share of 15% compares with 16%, and its electric-heat share of 32% with 32%. 6,262 occupied homes (6%) burn propane or other tank gas and 485 (0%) heat with wood, which matters because neither fuel comes with a gas utility's program attached. 74% of occupied homes are owner-occupied and 79% of all homes are single-family detached houses.
In Madison County that adds up to 46,573 homes from the 1950s to the 1970s, the usual candidates for an attic top-up; 22,248 built since 2000, where air sealing tends to matter more than extra depth.
| Built | Homes | Share | |
|---|---|---|---|
| Before 1940 | 17,395 | 15% | |
| 1940s | 8,750 | 7% | |
| 1950s | 17,278 | 14% | |
| 1960s | 14,189 | 12% | |
| 1970s | 15,106 | 13% | |
| 1980s | 11,057 | 9% | |
| 1990s | 13,145 | 11% | |
| 2000s | 14,019 | 12% | |
| 2010s | 7,132 | 6% | |
| 2020 or later | 1,097 | 1% |
Figures: U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates (tables B25001, B25003, B25024, B25034, B25035, B25040). Survey estimates carry margins of error, widest in the smallest places. Census table.
Madison County is on the Illinois side, where Ameren Illinois publishes discounts the contractor applies on the invoice: $1.10 per square foot for attic or wall insulation, $2.50 per linear foot for rim joist, $3.75 per linear foot for crawl space wall and $0.70 per cubic foot per minute (CFM) of air leakage reduced for air sealing on Ameren Illinois' 2026 discount table. The discount comes off a registered Ameren Illinois Program Ally's price, once the program's home energy assessment confirms the house is eligible. Income-qualified households can apply to Madison County Community Development (618-692-8940) for free weatherization instead. For every condition attached, see the rebate guide.
Nothing published settles it. None of the 5 jurisdictions we cover in Madison County lists insulation as permit work or as exempt, so the answer comes from a call to the building department before the job starts. Each town page gives that department's number.
R-49 for new work, in all 5 jurisdictions we cover in Madison County (Alton, Collinsville, Edwardsville, Glen Carbon, Granite City). The Department of Energy's recommendation for an uninsulated attic in this climate zone is higher, at R60.
The Census Bureau's 2020–2024 estimates put 15% of Madison County's 119,168 homes before 1940 and 61% before 1980, with a median year built of 1971.
For most addresses across Madison County it is Ameren Illinois, whose 2026 table publishes $1.10 per square foot for attic insulation and $0.70 per cubic foot per minute (CFM) of air leakage reduced for air sealing, taken off a registered Program Ally's price once the program's home energy assessment confirms the house is eligible.
Yes, through the Illinois low-income weatherization program, which Madison County Community Development runs for Madison County (618-692-8940). If the household income qualifies, the work can be free rather than discounted.
Free assessment, a measured R-value, and photos you keep either way.
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