Attic insulation, air sealing, crawl spaces and walls for homes in Arnold — starting with a free assessment that measures the R-value you actually have. The typical home here dates to the late-1970s, and 2% of its 8,982 homes went up before 1940.
Arnold runs to about 12 square miles and roughly 20,956 people. It sits about 15 miles south of downtown St. Louis. That is roughly 8,982 housing units. The community dates back to 1972. We cover ZIP code 63010.
Our job history shows nothing in Arnold so far. Plenty of sites will show you a number here anyway.
The typical home in Arnold dates to around the late-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 built from the 1960s into the 1970s, around the time of the city's 1972 incorporation.
We work across Arnold rather than one corner of it — Beck, Flamm City, Maxville, Old Town Arnold, Ten Brook and Wickes 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.
Arnold was formed in 1972 by the merger of six older communities (Beck, Flamm City, Maxville, Old Town Arnold, Ten Brook and Wickes). Sitting near the Meramec-Mississippi confluence, it has a documented history of major flooding, including a record Meramec River crest of 47.26 feet on Dec. 31, 2015 that affected more than 300 homes.
The Census Bureau estimates 8,982 homes in Arnold. 162 of them (2%) went up before 1940 — 31st of 44 places on this site for pre-1940 housing. The 1960s were the busiest decade, adding 2,307 of today's homes (26%); 54% predate 1980 and 16% were built in 2000 or later. For Jefferson County as a whole the pre-1940 share is 3%, so Arnold sits below it.
Of 8,394 occupied homes, 65% heat with utility gas and 31% with electricity; another 2% burn propane or other tank gas. Electric heat here is less common than across the county (58%), and ranks 26th 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.
80% of occupied homes are owner-occupied and 79% of all homes are single-family detached houses, with 310 mobile homes in the count. With houses like these, the conversations we expect most are about an attic top-up over postwar fiberglass and an energy assessment before deciding what to fix first.
| Built | Homes | Share | |
|---|---|---|---|
| Before 1940 | 162 | 2% | |
| 1940s | 136 | 2% | |
| 1950s | 1,077 | 12% | |
| 1960s | 2,307 | 26% | |
| 1970s | 1,195 | 13% | |
| 1980s | 1,024 | 11% | |
| 1990s | 1,626 | 18% | |
| 2000s | 905 | 10% | |
| 2010s | 473 | 5% | |
| 2020 or later | 77 | 1% |
8,982 homes, Census ACS 2020–2024 (B25034, B25040, B25003); 8,394 occupied.
2,650 of Arnold's 8,982 homes (30%) 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.
Arnold enforces the 2021 IECC. Section 500.010(A)(1)(f) of the Arnold city code adopts the International Energy Conservation Code including Appendices CA, CB, RA and RB as part of the 2021 family of I-Codes, incorporated by reference. The adopting ordinances are Ordinance No. 14.541, Bill No. 2761, effective 12-19-2019, as amended by Ordinance No. 14.558, Bill No. 2831, effective 7-21-2022. The city's Building and Code Compliance page states plainly that the 2021 International Energy Conservation Code is the adopted energy code, alongside the 2021 IBC, IRC, IPC, IMC and IFC and the 2020 NEC.
There is no published answer for Arnold. Neither the permit-required list nor the exemption list mentions insulation or air sealing at all. The Building and Code Compliance page says generally that the construction, remodeling or demolition of buildings and structures requires a permit and related inspections. The permits page names buildings, fences, retaining walls with over 2 feet of exposed face, signs, and sheds over 200 square feet. Insulation, weatherization and air sealing are not named on either list. That silence is not permission and it is not a prohibition. We settle it with a phone call before the crew is scheduled.
The published number is 636-282-2378. The department page is here.
Permitting is on us, not on you.
Arnold is on the Missouri side, where most addresses buy their electricity from Ameren Missouri. Its Pay As You Save program publishes $0.20 per square foot on ceiling and attic insulation and $0.06 per square foot on air sealing for the 2026 program year; the incentive comes off the cost and the rest is repaid through a monthly charge on the 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 Jefferson-Franklin Community Action Corp. (JFCAC) (636-789-2686) for free weatherization instead. For every condition attached, see the Jefferson County page or the rebate guide.
Every layer of an insulated attic, explained
Elsewhere in Jefferson County we also cover:
Also on this site, in neighboring St. Louis County:
Missouri sets none of this at state level. Across the 3 places in this table there are 2 different adopted editions (2015 IECC and 2021 IECC), and none of the 3 publishes a permit rule for insulation.
| City | Energy code | Attic R required | Permit to insulate | Building dept. |
|---|---|---|---|---|
| Arnold | 2021 IECC | — | Not published | 636-282-2378 |
| Festus | Not published | — | Not published | 636-937-6646 |
| Imperial | 2015 IECC | R-49 | Not published | 636-797-5555 |
All 3 Jefferson County jurisdictions side by side →
Arnold 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.
Arnold has not published a rule for it; the building department at 636-282-2378 is called before the job starts.
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 Arnold dates to around the late-1970s; the Census Bureau's 2020-2024 median year built is 1977. Of its 8,982 homes, 2% went up before 1940 and 16% 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: ecode360.com · arnoldmo.org (2, 3) · 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 636-282-2378 or your electric utility first.
Free assessment, a measured R-value, and photos you keep either way.
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