Insulation and air sealing for Swansea 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-1990s, and 5% of its 6,175 homes went up before 1940.
Swansea runs to about 6.5 square miles and roughly 14,445 people. It sits about 12 miles east of downtown St. Louis. Around 6,175 housing units sit inside those boundaries. The community dates back to 1886. We cover ZIP code 62226.
No completed job in Swansea is logged in our records yet, and this page will say so until one is.
The typical home in Swansea dates to around the early-1990s. Houses of this vintage usually got batts or blown fiber at whatever the standard of the day was, which is well short of what is recommended now. Most are one top-up away from being right.
Despite incorporating in 1886, Swansea's housing stock is a later 20th-century Metro East bedroom-suburb build-out rather than a preserved 19th-century core.
Swansea (originally "New Swansea") incorporated on December 20, 1886 specifically so residents could avoid annexation by Belleville.
The Census Bureau estimates 6,175 homes in Swansea. 313 of them (5%) went up before 1940 — 23rd of 44 places on this site for pre-1940 housing. The 2000s were the busiest decade, adding 1,378 of today's homes (22%); 32% predate 1980 and 37% were built in 2000 or later. For St. Clair County as a whole the pre-1940 share is 13%, so Swansea sits below it.
Of 5,777 occupied homes, 68% heat with utility gas and 31% with electricity. Electric heat here is less common than across the county (33%), and ranks 27th of 44 on this site. That is why the assessment asks how the house is heated: the fuel and the name on the utility bill decide which program, if any, can pay toward the work.
73% of occupied homes are owner-occupied and 70% of all homes are single-family detached houses, with 578 mobile homes in the count. Read together, those numbers point toward air sealing on newer houses that already have depth and an energy assessment before deciding what to fix first.
| Built | Homes | Share | |
|---|---|---|---|
| Before 1940 | 313 | 5% | |
| 1940s | 160 | 3% | |
| 1950s | 539 | 9% | |
| 1960s | 504 | 8% | |
| 1970s | 489 | 8% | |
| 1980s | 719 | 12% | |
| 1990s | 1,183 | 19% | |
| 2000s | 1,378 | 22% | |
| 2010s | 880 | 14% | |
| 2020 or later | 10 | 0% |
6,175 homes, Census ACS 2020–2024 (B25034, B25040, B25003); 5,777 occupied.
1,902 of Swansea's 6,175 homes (31%) were built in the 1980s and 1990s. The gaps in houses of that age are the parts nobody sealed: batts stuffed into the rim joist, bare spots over cathedral and tray ceilings, soffit vents buried with no baffles, can lights punched through the ceiling plane. A top-up plus a day of sealing usually covers it.
Swansea enforces the Illinois Energy Conservation Code (2024 IECC with Illinois amendments), by state law. The Illinois Energy Conservation Code governs residential energy work by statute.
For new work, the attic number under that edition is R-49, with walls at R-20 + R-5 continuous, or R-13 + R-10 continuous. Set that against the Department of Energy, which recommends R60 for an uninsulated attic in this climate zone and R49 for one that already has a few inches.
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.
Nothing Swansea publishes settles this. Its permit lists name the work types it cares about, and insulation is not among them in either direction. The Village's published permit types are electrical, plumbing, residential building, commercial building, HVAC, grading, sign and solar panel. Insulation is not among them. The residential page says a building permit is required before starting construction and that remodeling may need a building permit, without listing which work triggers it. So we ask the department directly before the first day on site, and whatever comes back, pulling it is our job rather than yours.
No registration or licensing requirement is published. The Village says its Building Department is a resource for securing current licensed and bonded contractor information, which is a referral service rather than a registry.
The published number is 618-234-0044. The department page is here.
Permitting is on us, not on you.
Ameren Illinois serves most Swansea 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. The full program rules are on the St. Clair County page and in the rebate guide.
Every layer of an insulated attic, explained
Swansea borders Fairview Heights, Belleville, O'Fallon and Shiloh. These are the ones we also cover, each with its own energy code and permit rule:
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. |
|---|---|---|---|---|
| Swansea | Illinois state code | R-49 | Not published | 618-234-0044 |
| Fairview Heights | Illinois state code | R-49 | Not published | 618-489-2060 |
| Belleville | Illinois state code | R-49 | Not published | 618-233-6817 |
| O'Fallon | Illinois state code | R-49 | Not published | 618-624-4500 |
All 4 St. Clair County jurisdictions side by side →
Swansea 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.
Not on paper: Swansea names neither a permit nor an exemption for insulation, so one call to the department at 618-234-0044 settles it first.
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 Swansea dates to around the early-1990s; the Census Bureau's 2020-2024 median year built is 1993. Of its 6,175 homes, 5% went up before 1940 and 37% 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: swanseail.org (2, 3) · codelibrary.amlegal.com (2) · en.wikipedia.org · city-data.com · ameren.com (2, 3, 4) · energystar.gov · data.census.gov. These change; confirm with the building department at 618-234-0044 or your electric utility first.
Free assessment, a measured R-value, and photos you keep either way.
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