Insulation and air sealing for Chesterfield 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-1980s, and 1% of its 21,603 homes went up before 1940.
Chesterfield runs to about 32 square miles and roughly 49,574 people. It sits about 25 miles west of downtown St. Louis. Around 21,603 housing units sit inside those boundaries. The community dates back to 1988. We cover ZIP codes 63005 and 63017.
No completed job in Chesterfield is logged in our records yet, and this page will say so until one is.
The typical home in Chesterfield dates to around the early-1980s. 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.
Mostly built from the 1970s through the 1980s (about 32% in the 1970s, 23% in the 1980s).
We work across Chesterfield rather than one corner of it — Bellefontaine, Lake, Gumbo, Monarch and Bonhomme included. Construction and vintage change between them, sometimes by thirty years and a whole different framing method, which decides whether a wall can be dense-packed at all.
Incorporated in 1988 out of several older communities, Chesterfield includes the Missouri River floodplain historically known as Gumbo Flats (now Chesterfield Valley). A violent F4 tornado cut a 21-mile path across St. Louis County on January 24, 1967, and the Gumbo Flats levee failed on July 30, 1993 -- the first levee failure there since 1935 -- flooding the valley.
The Census Bureau estimates 21,603 homes in Chesterfield. 302 of them (1%) went up before 1940 — 32nd of 44 places on this site for pre-1940 housing. The 1970s were the busiest decade, adding 6,895 of today's homes (32%); 46% predate 1980 and 17% were built in 2000 or later. For St. Louis County as a whole the pre-1940 share is 10%, so Chesterfield sits below it.
Of 20,811 occupied homes, 74% heat with utility gas and 25% with electricity. Electric heat here is more common than across the county (23%), and ranks 34th 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.
78% of occupied homes are owner-occupied and 63% of all homes are single-family detached houses, with 126 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 | 302 | 1% | |
| 1940s | 74 | 0% | |
| 1950s | 332 | 2% | |
| 1960s | 2,397 | 11% | |
| 1970s | 6,895 | 32% | |
| 1980s | 4,891 | 23% | |
| 1990s | 3,143 | 15% | |
| 2000s | 2,184 | 10% | |
| 2010s | 905 | 4% | |
| 2020 or later | 480 | 2% |
21,603 homes, Census ACS 2020–2024 (B25034, B25040, B25003); 20,811 occupied.
8,034 of Chesterfield's 21,603 homes (37%) 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.
Chesterfield does not publish the energy code edition it enforces, so this page does not name one. Chapter 500, Article I of the Chesterfield city code adopts, by Ordinance No. 3112 dated August 3, 2020, the 2015 International Building Code, the 2015 International Residential Code for One- and Two-Family Dwellings, the 2015 International Existing Building Code, the 2015 International Mechanical Code, the 2014 National Electrical Code, the 2015 Uniform Plumbing Code and the 2015 International Swimming Pool and Spa Code. No section of that article adopts an International Energy Conservation Code, and the word 'energy' does not appear in the article. The amendments to the residential code are held in an attachment to the chapter, called Attachment B, which is not printed in the online code, so whether Chapter 11 Energy Efficiency of the 2015 IRC was retained or deleted cannot be read online. The State of Missouri's building-codes-by-city list shows no energy code for Chesterfield. Across this metro the adopted editions run from the 2015 IECC to the 2024 IECC, and several jurisdictions have no energy code at all, which is a wide spread. Ask which one your contractor is building to.
Nothing Chesterfield publishes settles this. Its permit lists name the work types it cares about, and insulation is not among them in either direction. The city's building permit pages describe permits generally as ensuring work is structurally sound and complies with building and zoning codes. No published list of work requiring or exempt from a permit names insulation, air sealing or weatherization. So we ask the department directly before the first day on site, and whatever comes back, pulling it is our job rather than yours.
Nothing the city publishes on its building permit pages states that a contractor, or an insulation contractor specifically, must register or be licensed with Chesterfield.
The published number is 636-537-4000. The department page is here.
Permitting is on us, not on you.
Most Chesterfield addresses are Ameren Missouri electric customers, and Ameren Missouri pays toward insulation through Pay As You Save: $0.20 per square foot on the attic and $0.06 per square foot on air sealing in the 2026 program year, with the rest of the cost recovered through the electric bill. The conditions: an attic going from R-20 or below to at least R-38, air sealing that cuts measured leakage by 20 percent, and twelve months in the home. CommunitySavers can include attic insulation at no charge for income-eligible households. Income-qualified households can apply to Community Action Agency of St. Louis County (CAASTLC) (314-863-0015) for free weatherization instead. For every condition attached, see the St. Louis County page or the rebate guide.
Every layer of an insulated attic, explained
Chesterfield borders Town and Country. These are the ones we also cover, each with its own energy code and permit rule:
Elsewhere in St. Louis County we also cover:
Missouri sets none of this at state level. Across the 7 places in this table there are 4 different adopted editions (2015 IECC, 2018 IRC ch. 11, 2021 IECC and 2024 IECC), and 1 of the 7 publishes a permit rule for insulation.
| City | Energy code | Attic R required | Permit to insulate | Building dept. |
|---|---|---|---|---|
| Chesterfield | Not published | — | Not published | 636-537-4000 |
| Town and Country | 2018 IRC ch. 11 | R-49 | Not published | 314-587-2820 |
| Affton | 2015 IECC | R-49 | Not for an attic top-up | 314-615-5184 |
| Ballwin | Not published | — | Not published | 636-227-2129 |
| Brentwood | 2024 IECC | R-49 | Not published | 314-963-8602 |
| Clayton | 2021 IECC | R-60 | Not published | 314-290-8463 |
| Creve Coeur | 2015 IECC | R-49 | Not published | 314-872-2500 |
All 21 St. Louis County jurisdictions side by side →
Chesterfield does not publish the energy code edition it enforces, so we do not state a required figure here. The Department of Energy recommends R60 for an uninsulated attic in this climate zone and R49 where there are already a few inches.
Not on paper: Chesterfield names neither a permit nor an exemption for insulation, so one call to the department at 636-537-4000 settles it first.
For most Ameren Missouri customers, Pay As You Save: $0.20 per square foot on an attic starting at R-20 or lower and $0.06 per square foot on air sealing in 2026, the rest repaid on the bill. The federal 25C credit ended for work placed in service after December 31, 2025.
The typical home in Chesterfield dates to around the early-1980s; the Census Bureau's 2020-2024 median year built is 1982. Of its 21,603 homes, 1% went up before 1940 and 17% in 2000 or later. It is a median for the place, not a survey of individual houses.
Code and permit facts checked September 10, 2026, rebates October 24, 2026; housing: Census ACS 2020–2024. Sources: ecode360.com (2) · chesterfield.mo.us · content.civicplus.com · data.mo.gov · 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 636-537-4000 or your electric utility first.
Free assessment, a measured R-value, and photos you keep either way.
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