Attic insulation, air sealing, crawl spaces and walls for homes in Oakville — starting with a free assessment that measures the R-value you actually have. Oakville enforces the 2015 IECC, which sets R-49 for a new attic.
Oakville runs to about 18 square miles and roughly 36,301 people. It sits about 15 miles south of downtown St. Louis. There are around 14,242 housing units here. We cover ZIP code 63129.
We have not logged a completed job in Oakville yet. We would rather say so than put a number on this page that is not real.
The typical home in Oakville 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.
Louis by the city's own description.
The Census Bureau estimates 14,242 homes in Oakville. 283 of them (2%) went up before 1940 — 30th of 44 places on this site for pre-1940 housing. The 1970s were the busiest decade, adding 4,079 of today's homes (29%); 44% predate 1980 and 16% were built in 2000 or later. For St. Louis County as a whole the pre-1940 share is 10%, so Oakville sits below it.
Of 13,914 occupied homes, 74% heat with utility gas and 24% with electricity. Electric heat here is more common than across the county (23%), and ranks 36th 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.
86% of occupied homes are owner-occupied and 80% of all homes are single-family detached houses. With houses like these, the conversations we expect most are about an attic top-up over postwar fiberglass.
| Built | Homes | Share | |
|---|---|---|---|
| Before 1940 | 283 | 2% | |
| 1940s | 232 | 2% | |
| 1950s | 567 | 4% | |
| 1960s | 1,108 | 8% | |
| 1970s | 4,079 | 29% | |
| 1980s | 3,610 | 25% | |
| 1990s | 2,079 | 15% | |
| 2000s | 1,827 | 13% | |
| 2010s | 457 | 3% | |
| 2020 or later | 0 | 0% |
14,242 homes, Census ACS 2020–2024 (B25034, B25040, B25003); 13,914 occupied.
5,689 of Oakville's 14,242 homes (40%) 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.
Oakville enforces the 2015 IECC. Oakville is unincorporated St. Louis County, so permitting and code enforcement are the county's. The Missouri state building code database published at data.mo.gov lists Oakville with the 2015 IECC, the 2015 IRC and the 2015 IBC.
For new work, the attic number under that edition is R-49, with walls at R-20, or R-13 plus R-5 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 R402.1.2 of the 2015 IECC, climate zone 4 except marine, per the U.S. Department of Energy's 'Residential Provisions of the 2015 International Energy Conservation Code' (ceiling 49; wood frame wall 20 or 13+5).
This is unincorporated St. Louis County, so the county's Division of Code Enforcement is the permit desk here. Item 35 of its no-permit list exempts increasing attic insulation and adding exterior wall insulation under new siding, but insulating the room side of an exterior wall needs a building permit.
The county's full no-permit list, and what it says about walls and basements, is set out on the unincorporated St. Louis County page.
The published number is 314-615-5184. The department page is here.
Permitting is on us, not on you.
Oakville 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 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
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 3 different adopted editions (2015 IECC, 2021 IECC and 2024 IECC), and 2 of the 7 publish a permit rule for insulation.
| City | Energy code | Attic R required | Permit to insulate | Building dept. |
|---|---|---|---|---|
| Oakville | 2015 IECC | R-49 | Not for an attic top-up | 314-615-5184 |
| 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 |
| Chesterfield | Not published | — | Not published | 636-537-4000 |
| 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 →
Oakville enforces the 2015 IECC, which sets R-49 for an attic in new work. Whether it reaches a retrofit of an existing house is not published.
This is unincorporated St. Louis County, so the county's Division of Code Enforcement is the permit desk here. Item 35 of its no-permit list exempts increasing attic insulation and adding exterior wall insulation under new siding, but insulating the room side of an exterior wall needs a building permit.
Ameren Missouri's Pay As You Save: $0.20 per square foot for an attic starting at R-20 or below and $0.06 per square foot for air sealing in 2026, with the balance on the electric bill. The federal 25C credit ended for work placed in service after December 31, 2025.
The typical home in Oakville dates to around the early-1980s; the Census Bureau's 2020-2024 median year built is 1982. Of its 14,242 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: data.mo.gov (2) · library.municode.com · manchestermo.gov · energycodes.gov · dnr.mo.gov · onestl.org · cityofwildwood.com · ecode360.com (2, 3) · basc.pnnl.gov · stlouiscountymo.gov · en.wikipedia.org · bestplaces.net · ameren.com (2, 3, 4) · energystar.gov · data.census.gov. These change; confirm with the building department at 314-615-5184 or your electric utility first.
Free assessment, a measured R-value, and photos you keep either way.
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