Insulating a house in Swansea runs on one state energy code, not a local one — here is the R-value it sets, what the city does and does not ask a permit for, the Ameren Illinois discount your address qualifies for, and how old the housing here really is.
Swansea runs to about 6.5 square miles and roughly 14,445 people. It sits about 12 miles east of downtown St. Louis. Around 6,444 housing units sit inside those boundaries, most of them built before anyone measured a house for air leakage. 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 fibre 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.
Housing from this stretch in Swansea generally got a real attempt at insulation — a real layer in the attic, batts in the walls — so the argument here is rarely about starting from nothing. It is about the gap between what was standard then and what is recommended now, and about the parts nobody insulated at all. Recurring finds: batts stuffed into the rim joist rather than sealed, insulation missing entirely above a cathedral or tray ceiling, soffit vents blocked solid by insulation blown over them with no baffles, and can lights punched straight through the ceiling plane. A house from this era is usually a top-up plus a day of sealing, not a rebuild.
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.
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 this climate zone 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.
Nothing Swansea publishes settles this. Its permit lists name the work types it cares about, and insulation is not among them in either direction. That is the normal state of affairs across this metro — only a handful of the 45 jurisdictions on this site say anything about it at all. 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.
Swansea is on the Illinois side, and the Illinois programme is the more generous of the two by a wide margin. Ameren Illinois publishes flat per-unit discounts applied by the contractor rather than mailed to you as a cheque. On Ameren Illinois' 2026 discount table: $1.10 per square foot for attic insulation and the same for wall insulation, $2.00 per linear foot for rim joist, $3.00 per linear foot for crawl space wall, and $0.70 per cubic foot per minute (CFM) of air leakage reduced for air sealing.
Two conditions decide whether any of that reaches you. Air sealing has to be pre-approved before the work starts — do it first and ask afterwards and the money is gone. And only a registered Ameren Illinois Program Ally can apply the discount at all: a contractor who is not on that list cannot get it for you, whatever they say on the doorstep. Ask which they are before you sign.
Compare that with the Missouri side of the metro, where the same attic gets an on-bill programme paying $0.20 per square foot instead, and only if the attic started at R-20 or below. Same weather, same houses, different utility regulator.
If the household income qualifies, the work can be free rather than discounted. St. Clair County is served by St. Clair County Community Action Agency under the Illinois low-income weatherization program — 618-277-6790, details here.
One more, by its absence: the federal 25C credit, which covered 30% of insulation and air sealing up to $1,200 a year, ended for anything placed in service after 31 December 2025. Work finished on or before that date is still claimed on that year's return; nothing done in 2026 is. It should not be in your 2026 price, whoever tells you otherwise — the rebate guide has the detail.
NOAA's 1991–2020 normals put 84.9 nights a year at or below freezing here, and only 19.3 days that never climb back above it. Most freezes in Swansea thaw the same day, and that daily cycling is what drives moisture into a cold attic. The energy code and rebate guide has the full climate figures.
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 these figures agree across the county — what changes here is the permit desk, not the R-value.
| 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 |
Free assessment, a measured R-value, and photos you keep either way.
The code edition Swansea enforces sets R-49 for new work. The Department of Energy separately recommends R60 for an uninsulated attic in this climate zone, and R49 where a few inches are already there.
Unresolved on paper. Swansea names the work types it wants permits for and insulation is not one of them, but nor is it on the exemption list. It gets settled by phone before we schedule, at our end.
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 on its 2026 discount table, applied by the contractor rather than paid to you directly. Two conditions decide whether it reaches you: air sealing has to be pre-approved before the work starts, and only a registered Ameren Illinois Program Ally can apply the discount at all. The federal 25C credit ended for work placed in service after 31 December 2025.
The typical home in Swansea dates to around the early-1990s. Houses of this vintage usually got batts or blown fibre 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. That figure is an ACS-derived median republished by housing-data services, not a survey of individual houses.
Not yet. We have no completed job logged in Swansea, and we would rather say so than put a number on this page that is not real.
Illinois does not license insulation contractors as a trade, though it does run the residential energy code from Springfield rather than leaving it to each city. Municipal registration varies — some Metro East cities require a business licence, others require none at all. What matters more in practice is whether the contractor is a registered Ameren Illinois Program Ally, because only an Ally can apply the rebate.
Energy code, permit and department details for Swansea come from the jurisdiction's own published pages and codified ordinances. Rebate figures come from the utility's own published incentive tables and carry the programme year they were verified in. Housing-age figures are ACS-derived medians republished by housing-data services, so treat them as approximate. Sources: swanseail.org · swanseail.org · codelibrary.amlegal.com · codelibrary.amlegal.com · swanseail.org · en.wikipedia.org · city-data.com · ameren.com · ameren.com · ameren.com · ameren.com · energy.gov. Adopted code editions, department phone numbers and utility rebate amounts all change — confirm with the jurisdiction or the utility before relying on anything here.