Attic insulation, air sealing, crawl spaces and walls for homes in Collinsville — starting with a free assessment that measures the R-value you actually have. The typical home here dates to the early-1970s, and 17% of its 11,644 homes went up before 1940.
Collinsville runs to about 15 square miles and roughly 24,031 people. It sits about 12 miles east of downtown St. Louis. There are around 11,644 housing units here. The community dates back to 1850. We cover ZIP code 62234.
We have not logged a completed job in Collinsville yet. We would rather say so than put a number on this page that is not real.
The typical home in Collinsville dates to around the early-1970s. 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.
Mostly mid-20th-century, with only about 17% of homes predating 1940.
German-American settlers arrived by Conestoga wagon in 1812; the town adopted a village charter in 1850 and became a city in 1872. The Brooks Catsup Bottle water tower, listed on the National Register of Historic Places, is the city's best-known historic structure.
The Census Bureau estimates 11,644 homes in Collinsville. 1,970 of them (17%) went up before 1940 — 11th 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 61% predate 1980. For Madison County as a whole the pre-1940 share is 15%, so Collinsville sits above it.
Of 11,061 occupied homes, 61% heat with utility gas and 37% with electricity. Electric heat here is more common than across the county (32%), and ranks 15th of 44 on this site. Whoever comes out will ask about the furnace or heat pump first, since the heating fuel and the utility named on the bill settle which program money is on the table.
66% of occupied homes are owner-occupied and 66% of all homes are single-family detached houses, with 400 mobile homes in the count. Read together, those numbers point toward an attic top-up over postwar fiberglass and an energy assessment before deciding what to fix first.
| Built | Homes | Share | |
|---|---|---|---|
| Before 1940 | 1,970 | 17% | |
| 1940s | 723 | 6% | |
| 1950s | 1,427 | 12% | |
| 1960s | 1,589 | 14% | |
| 1970s | 1,441 | 12% | |
| 1980s | 1,649 | 14% | |
| 1990s | 1,175 | 10% | |
| 2000s | 1,151 | 10% | |
| 2010s | 490 | 4% | |
| 2020 or later | 29 | 0% |
11,644 homes, Census ACS 2020–2024 (B25034, B25040, B25003); 11,061 occupied.
4,457 of Collinsville's 11,644 homes (38%) 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.
Collinsville enforces the Illinois Energy Conservation Code (2024 IECC with Illinois amendments), by state law. Collinsville's building permits page states the city adopted the 2021 ICC codes effective January 1, 2025. The Illinois Energy Conservation Code governs residential energy work by statute.
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 Collinsville 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. Collinsville lies in Madison and St. Clair counties, both in climate zone 4 per the NAIMA IECC compliance guide for Illinois homes.
Collinsville publishes no answer either way. Insulation and air sealing appear on neither the permit-required list nor the exempt list. Insulation is not among the named examples, and the list is not presented as exhaustive; the city asks residents to call if unsure. 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.
No contractor registration or licensing requirement is published on the city's building permits page or in its applications and forms list. The city publishes an architects and engineers contact list, not a contractor registry.
The published number is 618-346-5200. The department page is here.
Permitting is on us, not on you.
Ameren Illinois serves most Collinsville 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 Madison County Community Development (618-692-8940) for free weatherization instead. The full program rules are on the Madison County page and in the rebate guide.
Every layer of an insulated attic, explained
Collinsville borders Maryville, Pontoon Beach, Fairmont City and Caseyville.
Elsewhere in Madison 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 5 publishes a permit rule for insulation.
| City | Energy code | Attic R required | Permit to insulate | Building dept. |
|---|---|---|---|---|
| Collinsville | Illinois state code | R-49 | Not published | 618-346-5200 |
| Alton | Illinois state code | R-49 | Not published | 618-463-3500 |
| 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 Madison County jurisdictions side by side →
Collinsville 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.
Collinsville publishes no rule either way, so we ask its building department at 618-346-5200 before the job is scheduled.
Ameren Illinois' 2026 table: $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 the invoice by a registered Program Ally following a home energy assessment. The federal 25C credit ended for work placed in service after December 31, 2025.
The typical home in Collinsville dates to around the early-1970s; the Census Bureau's 2020-2024 median year built is 1971. Of its 11,644 homes, 17% went up before 1940 and 14% in 2000 or later. That is a median across the whole place, so your own house may be older or newer.
Code and permit facts checked September 10, 2026, rebates October 24, 2026; housing: Census ACS 2020–2024. Sources: collinsvilleil.org (2, 3) · library.municode.com · en.wikipedia.org · ci.collinsville.il.us · censusreporter.org · point2homes.com · ameren.com (2, 3, 4) · energystar.gov · data.census.gov. These change; confirm with the building department at 618-346-5200 or your electric utility first.
Free assessment, measured at the hatch, with the photographs and the number in writing.
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