Attic insulation, air sealing and crawl space work across Monroe County. We cover 2 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 14,759 homes, 10% were built before 1940, and 30% 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. |
|---|---|---|---|---|
| Columbia | Illinois state code | R-49 | Not published | 618-281-7144 |
| Waterloo | Illinois state code | R-49 | Not published | 618-939-8600 |
Both publish an energy code edition we could name and both 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 both places we cover in Monroe County. What changes from town to town is the permit desk.
Both places here with their own Census row hold 9,553 of Monroe County's 14,759 homes (65%); the rest are in other municipalities or unincorporated areas.
One detail worth knowing before a job in each of them:
Monroe County has 14,759 homes in the Census count, with a median year built of 1990. 41% were built before 1980 and 32% in 2000 or later; the single biggest decade was the 2000s, with 2,872 homes (19%). Of 13,851 occupied homes, 46% heat with utility gas and 30% with electricity.
Across the two places we cover here, Waterloo has the oldest housing (11% before 1940) and Columbia the newest (35% built in 2000 or later). Waterloo is the largest, at 4,818 homes, and Columbia has the most electric heat (41%).
| Place | Homes | Before 1940 | Median built | Electric heat | Owner-occupied |
|---|---|---|---|---|---|
| Waterloo | 4,818 | 11% | 1991 | 24% | 78% |
| Columbia | 4,735 | 8% | 1991 | 41% | 82% |
Against the eight-county metro on this site (1,177,290 homes), Monroe County's pre-1940 share of 10% compares with 16%, and its electric-heat share of 30% with 32%. 2,934 occupied homes (21%) burn propane or other tank gas and 237 (2%) heat with wood, which matters because neither fuel comes with a gas utility's program attached. 85% of occupied homes are owner-occupied and 84% of all homes are single-family detached houses.
In Monroe County that adds up to 4,036 homes from the 1950s to the 1970s, the usual candidates for an attic top-up; 4,698 built since 2000, where air sealing tends to matter more than extra depth.
| Built | Homes | Share | |
|---|---|---|---|
| Before 1940 | 1,450 | 10% | |
| 1940s | 524 | 4% | |
| 1950s | 1,090 | 7% | |
| 1960s | 1,665 | 11% | |
| 1970s | 1,281 | 9% | |
| 1980s | 1,290 | 9% | |
| 1990s | 2,761 | 19% | |
| 2000s | 2,872 | 19% | |
| 2010s | 1,635 | 11% | |
| 2020 or later | 191 | 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.
Monroe 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 Western Egyptian Economic Opportunity Council (serves Monroe, Perry and Randolph counties) (618-965-3458) for free weatherization instead. The full program rules are in the rebate guide.
Nothing published settles it. Neither of the two jurisdictions we cover in Monroe 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 both jurisdictions we cover in Monroe County (Columbia, Waterloo). 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 10% of Monroe County's 14,759 homes before 1940 and 41% before 1980, with a median year built of 1990.
For most addresses across Monroe 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 Western Egyptian Economic Opportunity Council (serves Monroe, Perry and Randolph counties) runs for Monroe County (618-965-3458). 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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