Windows and siding in St. Louis County
21 places we cover, and the rules that apply in each.
Missouri has no statewide building code and no statewide energy code. Adoption happens municipality by municipality, which is why the table below does not read like one county at all — it reads like 21 separate countries. Between them these places have adopted 10 different energy code arrangements.
69.2% of the housing in St. Louis County was built before 1980, and 9.6% before 1940 (42,898 of 445,472 units). That is the number that decides whether the federal lead rule is on your job, and on both of these trades it very often is: window replacement is never exempt from it at any size, and a whole-house re-side clears the exterior threshold immediately.
| Place | Permit to re-side? | Permit for a like-for-like window? | Adopted energy code | Window must meet |
|---|---|---|---|---|
| Affton | Depends | Depends | 2015 IRC energy provisions (no separate IECC adopted) | U-0.34 |
| Ballwin | Yes | Yes | None — the energy chapter is deleted | None adopted |
| Brentwood | Yes | Not published | 2024 IECC | U-0.28 |
| Chesterfield | Depends | Depends | 2015 IRC energy provisions (no separate IECC adopted) | U-0.34 |
| Clayton | Yes | Yes | 2021 IECC | U-0.30 |
| Creve Coeur | Not published | No | 2015 IECC (Seventh Edition) | U-0.35 |
| Des Peres | Yes | Yes | 2018 IRC energy provisions (no separate IECC adopted) | U-0.32 |
| Ellisville | Not published | Not published | Not published | — |
| Eureka | Depends | Depends | Not published | None adopted |
| Florissant | Depends | Yes | 2021 IECC | U-0.30 |
| Kirkwood | Not published | Not published | 2021 Energy Conservation Code | U-0.30 |
| Manchester | Depends | Depends | 2015 IRC energy provisions (no separate IECC adopted) | U-0.34 |
| Maryland Heights | Not published | Yes | 2015 IECC (as amended) | U-0.35 |
| Mehlville | Depends | Depends | 2015 IRC energy provisions (no separate IECC adopted) | U-0.34 |
| Oakville | Depends | Depends | 2015 IRC energy provisions (no separate IECC adopted) | U-0.34 |
| Richmond Heights | Not published | Not published | 2024 IECC | U-0.28 |
| Town and Country | Depends | No | Not published | None adopted |
| Unincorporated St. Louis County | Depends | Depends | 2015 IRC energy provisions (no separate IECC adopted) | U-0.34 |
| University City | Depends | Yes | 2018 IECC | U-0.32 |
| Webster Groves | Yes | Yes | 2015 IECC | U-0.35 |
| Wildwood | Depends | Depends | 2015 IRC energy provisions (no separate IECC adopted) | U-0.34 |
Things worth knowing before you sign anything
Affton
Affton is unincorporated, so St. Louis County is its building department and there is no city hall to call. Affton is an unincorporated census-designated place, not a municipality. It has no city government, no building department and no municipal code; permits for single-family work are issued by the St. Louis County Department of Transportation and Public Works, Residential Building section. That establishes the county ordinance number and date but not the I-Code editions behind it, not the permit-exemption list, and not any energy code.
Ballwin
Ballwin runs its own building department — it is one of the few cities in this part of the county that does not contract the work to St. Louis County. Dual licensing: Ballwin is the clearest case in this metro of a city that requires a contractor to hold both a city license and an active St. Louis County license in the relevant trade before pulling a permit - so a siding or window crew licensed only at the county level, or only in another municipality, cannot work. Second quirk: the published code edition is in flux (2015 standards in force, 2024 I-Codes proposed for 2026), and the proposed package conspicuously omits an energy code.
Brentwood
Brentwood also runs the newest code stack in this dataset — 2024 IRC (with a long appendix list), 2024 IBC and 2024 IECC.
Chesterfield
Chesterfield contracts with St. Louis County for building, residential and existing-building code enforcement, so the County’s exempt-work list and its U-0.34 window condition are what apply here. The city keeps property maintenance and land disturbance for itself. Chesterfield does not run a fully self-contained building department: City Code Section 500.020 provides that 'The City of Chesterfield, Missouri, is hereby authorized and directed to execute and enter into a contract on behalf of the City with St. Louis County, Missouri, for technical code enforcement services, which contract shall be on file in the City offices.' An editor's note confirms the current contract is on file rather than published, so the split between what the City handles and what County staff handle is not publicly documented. The city also runs a separate Architectural Review Process and a 'Planner of the Day' desk.
Clayton
Clayton is the strictest of the places we cover on the exterior envelope: no siding exemption, no window or glazing exemption, and a mandatory design-review layer on top. 'Exterior alterations require approval from the Architectural Review Board or receive administrative architectural review,' with published fees of $135 for ARB review and $85 for the administrative track - so a re-side or a window replacement carries a design-review cost and a meeting calendar, not just a permit. Doubling of permit fees for starting work before the permit issues (100% additional) is also expressly codified. Plumbing work uniquely requires a Master Plumber licensed by both St. Louis County and the City of Clayton.
Creve Coeur
Creve Coeur also adopts St. Louis County Mechanical, Plumbing and Electrical Codes rather than the I-Codes for those trades. Permitting runs through an outside portal at crevecoeur.onlama.com.
Des Peres
Des Peres contracts with St. Louis County for mechanical, electrical and plumbing inspection but keeps the building and residential codes in-house, so the County’s siding and window exemptions do not reach here. No architectural review board or design review body was found in any published Des Peres source, despite the city's affluence — unlike Town and Country and Brentwood, which both have one. Permit questions are routed to Public Works (Permits@DesPeresMO.org), not to a standalone building department.
Ellisville
Ellisville adopts the 2015 National Green Building Standard alongside the I-Codes — an unusual adoption for a St. Louis County municipality and the only green-building standard found in this metro. Permit review sits with the Engineering Department rather than a standalone building department. The building permit fee basis ($3.00 per $1,000, $15.00 minimum) is by a wide margin the cheapest in this metro.
Windows or siding in St. Louis County?
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