Insulation and air sealing for Belleville homes: attics, crawl spaces, rim joists and walls, starting with a free assessment of the R-value you actually have. The typical home here dates to the early-1960s, and 26% of its 20,212 homes went up before 1940.
Belleville runs to about 23 square miles and roughly 41,370 people. It sits about 14 miles southeast of downtown St. Louis. There are around 20,212 housing units here. The community dates back to 1819. We cover ZIP codes 62220, 62221, 62222, 62223, 62225 and 62226.
We have not logged a completed job in Belleville yet. We would rather say so than put a number on this page that is not real.
The typical home in Belleville dates to around the early-1960s. Postwar building here often meant three or four inches of fiberglass and no attempt at air sealing. If nobody has touched it since, that is what is still up there.
A mix of pre-1940 housing (about 26% of homes, including German-built row houses) and mid-20th-century construction.
Founded in 1814 and incorporated as a village in 1819, Belleville was heavily settled by German immigrants (an estimated 90% of the population was German-born or of German descent by 1870); their legacy includes 'German street house' row homes alongside later American Foursquare, Queen Anne and other Victorian-era construction concentrated in its historic districts.
The Census Bureau estimates 20,212 homes in Belleville. 5,341 of them (26%) went up before 1940 — 7th of 44 places on this site for pre-1940 housing. More of today's homes date from before 1940 than from any single decade since, and 72% predate 1980. For St. Clair County as a whole the pre-1940 share is 13%, so Belleville sits above it.
Of 17,646 occupied homes, 65% heat with utility gas and 32% with electricity; another 2% burn propane or other tank gas. Electric heat here is less common than across the county (33%), and ranks 23rd of 44 on this site. Which utility program can contribute depends on the heating fuel and on who sends the bill, so that is the first thing an assessment pins down.
60% of occupied homes are owner-occupied and 66% of all homes are single-family detached houses, with 438 mobile homes in the count. Read together, those numbers point toward wall insulation for walls built empty, a vermiculite check before anything is disturbed, an attic top-up over postwar fiberglass and an energy assessment before deciding what to fix first.
| Built | Homes | Share | |
|---|---|---|---|
| Before 1940 | 5,341 | 26% | |
| 1940s | 1,672 | 8% | |
| 1950s | 2,556 | 13% | |
| 1960s | 3,058 | 15% | |
| 1970s | 1,874 | 9% | |
| 1980s | 1,896 | 9% | |
| 1990s | 1,413 | 7% | |
| 2000s | 1,772 | 9% | |
| 2010s | 522 | 3% | |
| 2020 or later | 108 | 1% |
20,212 homes, Census ACS 2020–2024 (B25034, B25040, B25003); 17,646 occupied.
7,488 of Belleville's 20,212 homes (37%) date from 1950 through 1979. The leaks in houses of that era repeat: nothing over the top plates, wire and pipe holes left open, an unsealed hatch, a bath fan venting into the attic, and in ranches and split-levels, heat lost at the garage ceiling and over cantilevered floors. Sealing the plates, holes and fans comes before any more fiber, and it is usually a day's work, not a renovation.
Belleville enforces the Illinois Energy Conservation Code (2024 IECC with Illinois amendments), by state law. Belleville City Code ยง 150.01 adopts the 2006 International Building Code, the 2006 International Residential Code for One- and Two-Family Dwellings, and the International Energy Conservation Code. The ordinance names the International Energy Conservation Code without stating an edition. Because 20 ILCS 3125 makes the Illinois Energy Conservation Code both the floor and the ceiling for residential energy standards, the edition that governs a Belleville house is the state edition, currently the 2024 IECC as amended, effective 11/30/2025.
Under that edition the required attic value for new work here is R-49, and walls R-20 + R-5 continuous, or R-13 + R-10 continuous. For comparison, the Department of Energy recommends R60 for an uninsulated attic in climate zone 4A, where Belleville sits, and R49 where there are already a few inches up there.
Table R402.1.3 of the 2024 IECC as amended for Illinois, climate zone 4. St. Clair County is in climate zone 4 per the NAIMA IECC compliance guide for Illinois homes.
Belleville publishes no answer either way. Insulation and air sealing appear on neither the permit-required list nor the exempt list. The city says any improvements to private property within the corporate city limits require appropriate permits obtained through the Health, Housing & Building Department, but that is a general statement. Neither the department page nor the building permit application form names insulation, weatherization or attic work as a permit type. We confirm it with the department before we start and pull whatever is needed. We would rather write that here than guess on your behalf.
The city building permit application asks for a contractor name and a contractor ID number, which implies a city contractor file, but no published city page states a registration requirement or fee for insulation contractors. The department does maintain a list of approved electrical contractors.
The published number is 618-233-6817. The department page is here.
Permitting is on us, not on you.
Ameren Illinois serves most Belleville addresses, and its 2026 discount table pays $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, taken off the invoice. 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 St. Clair County Community Action Agency (618-277-6790) for free weatherization instead. For every condition attached, see the St. Clair County page or the rebate guide.
Every layer of an insulated attic, explained
Elsewhere in St. Clair County we also cover:
Illinois sets the residential energy code from Springfield, so the attic figure is R-49 wherever it is published here; what changes is the permit desk, and none of the 4 publishes a permit rule for insulation.
| City | Energy code | Attic R required | Permit to insulate | Building dept. |
|---|---|---|---|---|
| Belleville | Illinois state code | R-49 | Not published | 618-233-6817 |
| Fairview Heights | Illinois state code | R-49 | Not published | 618-489-2060 |
| O'Fallon | Illinois state code | R-49 | Not published | 618-624-4500 |
| Swansea | Illinois state code | R-49 | Not published | 618-234-0044 |
All 4 St. Clair County jurisdictions side by side →
Belleville enforces the Illinois state code, which sets R-49 for an attic in new work. That code also reaches work on existing houses, not only new ones.
Belleville publishes no rule either way, so we ask its building department at 618-233-6817 before the job is scheduled.
Ameren Illinois 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 for 2026; only a registered Program Ally can apply it, once an assessment shows the house qualifies. The federal 25C credit ended for work placed in service after December 31, 2025.
The typical home in Belleville dates to around the early-1960s; the Census Bureau's 2020-2024 median year built is 1962. Of its 20,212 homes, 26% went up before 1940 and 12% in 2000 or later. Half the homes here are older than that and half newer; yours may sit at either end.
Code and permit facts checked September 10, 2026, rebates October 24, 2026; housing: Census ACS 2020–2024. Sources: belleville.net (2, 3, 4) · codelibrary.amlegal.com (2) · jaspector.com · en.wikipedia.org · censusreporter.org · point2homes.com · ameren.com (2, 3, 4) · energystar.gov · data.census.gov. These change; confirm with the building department at 618-233-6817 or your electric utility first.
Free assessment, measured at the hatch, with the photographs and the number in writing.
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