Windows and siding in Jefferson County
3 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 3 separate countries. Between them these places have adopted 2 different energy code arrangements.
48.6% of the housing in Jefferson County was built before 1980, and 3.2% before 1940 (3,028 of 93,276 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 |
|---|---|---|---|---|
| Arnold | Yes | Yes | 2021 IECC (with Appendices CA, CB, RA, RB) | U-0.30 |
| Festus | Yes | Yes | Not published | — |
| Imperial | No | No | 2015 IECC | U-0.35 |
Things worth knowing before you sign anything
Arnold
Arnold sits inside Jefferson County, which expressly exempts siding replacement, same-opening window replacement AND single-family roof replacement from permit - but Arnold, as a home-rule city running its own building department, exempts essentially nothing (2-foot fences and 500-gallon water tanks only). A contractor working Imperial and Arnold on the same day faces opposite rules. Arnold also drops the model code's fence exemption from 6 or 7 feet down to 2 feet, which is the most aggressive amendment seen in this metro. Address: 2101 Jeffco Blvd; hours 8:00 a.m.-4:45 p.m.
Festus
Festus also publishes that 'Building or installing a fence in the City of Festus does not require a building permit' while simultaneously deleting the model code's accessory-structure exemption in Sec. 500.015 - so sheds are stricter and fences looser than the model code.
Imperial
A residing-and-windows job in Imperial needs no county building permit at all, provided the window openings and operation are unchanged. The 'operation do not change' clause is unique to Jefferson County within this group and is the trap: a like-for-like size swap that changes the window's operating type loses the exemption. Note also the split electrical adoption - NEC 2014 as modified by a locally written Jefferson County Electrical Code 2017. Permits and payments run through the Citizen Portal at civicgov4.com/mo_jeffersoncounty/portal; Code Enforcement is at 729 Maple Street, Hillsboro.
Windows or siding in Jefferson County?
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