Window and siding replacement in O'Fallon
What the code and the permit desk actually require here — and what the houses in O'Fallon tend to be hiding behind the siding.
- People
- 32,289
- Homes
- 13,225
- Size
- 15.7 square miles
- From downtown
- About 15 miles east
- ZIP codes
- 62269, 62225
- Founded or incorporated
- 1874
Founded in 1854 and incorporated as a village in January 1874 (city form of government adopted 1905), O'Fallon, IL sits near Scott Air Force Base, which has driven much of its subdivision growth.
O'Fallon
Median home age is about 25 years; housing is spread across many named platted subdivisions (Thornbury Hill, Nolin Creek Estates, Fairwood Hills, Deer Creek, Forest Hills, Fairwood East), reflecting late-20th-century subdivision-driven growth after the city's 1854 founding.
What that vintage turns up
First-generation vinyl replacements went in across this whole period and they are now hitting both of the ages that matter at once: the frames are inside the twenty-to-forty-year band and the sealed glass units are well past the eight-to-twenty-year band. That combination produces the most common call we get on houses this age — fogged glass in a frame that is still perfectly sound. The honest first answer there is replacing the glass unit, not the window.
Hardboard and wood-composite lap siding from this era is the one with the paperwork. Masonite's hardboard covered product installed between 1980 and 1998 and reached roughly four million homeowners; Louisiana-Pacific's Inner-Seal siding had its own national settlement in the mid-1990s. Both claim programmes closed years ago, so the relevance now is diagnostic rather than financial: swelling, delamination and mushrooming along the bottom edges of the boards on a house of this age is a known product history, not necessarily the owner having neglected it.
The one to watch on a house of this age
Synthetic stucco applied before about 1997 is the high-risk cohort. Roughly ninety-five per cent of American applications were the face-sealed kind, which has no way to drain what gets past it, and the failures traced back overwhelmingly to flashing that was left out. Drainable systems are a different animal and are not the problem.
Lead paint. No, for anything built after 1978 — but confirm the build year before assuming it. 55.3% of the homes in St. Clair County were built before 1980, and on anything pre-1978 the EPA renovation rule applies to both of these trades. Window replacement is never exempt from it, at any size — a single window triggers it. A whole-house re-side clears the twenty square foot exterior threshold on the first wall. What the rule actually requires of a contractor.
Neighbourhoods
We work across Thornbury Hill, Nolin Creek Estates, Fairwood Hills, Deer Creek, Forest Hills and Fairwood East.
The rules in O'Fallon
Siding replacement Not published
The only published permit-trigger statement found is on the city's business-requirements page: 'The City of O'Fallon issues building, plumbing, and electrical permits for any new construction and most interior renovations.' That sentence is about new construction and interior renovation and does not address exterior re-siding either way. So O'Fallon neither publishes a siding rule of its own nor amends the model code's list of exempt work.
Window replacement, same opening Not published Enlarging or cutting an opening Not published
Windows are addressed nowhere in O'Fallon's published material that could be reached. Sec. 150.06 (Residential Code amendments) does not touch permit scope, and the business-requirements page speaks only to 'new construction and most interior renovations.' Neither the same-opening case nor a new or enlarged opening is published.
Illinois sets this, not O'Fallon — and we are not going to print a number we have not read
O’Fallon is the only city in the Metro East group with a codified energy section of its own, Section 150.09. Its entire text is: “The Energy Code is hereby adopted with no amendments.” In other words it defers completely to the statewide Illinois Energy Conservation Code. The city moved to the 2021 I-codes by Ordinance 4348, adopted 17 November 2025, effective 1 January 2026.
The unamended 2024 code figure for this climate zone is U-0.28. But Illinois publishes its own amendments to that code, it has amended that very table before, and we have not been able to open the current amendment document. So we are not going to state U-0.28 as the number enforced here. Buy to the ENERGY STAR figure below and the question does not arise; if you need the exact legal minimum, the Capital Development Board’s energy code office is on 217-685-4079.
For comparison, ENERGY STAR asks for U-0.25 or lower with an SHGC of 0.40 or lower everywhere in this metro, which is stricter than every code edition in force here. And the code only bites when the sash and the glazing are replaced together — replace the glass alone in an existing sash, or add a storm window over the top, and it does not apply.
Contractor registration Depends
What is published is a general business registration, not a construction-contractor registration: 'A City-issued Business Registration from the City Clerk's office is generally required before any business may commence operation,' issued in 5-10 business days and renewed annually. The page does not say whether a non-resident siding or window contractor pulling a permit falls inside 'any business may commence operation,' and it specifies NO bond or insurance requirement. No separate construction-contractor registration, bond or certificate-of-insurance requirement was found. Verify by phone before treating this as a registration requirement for a remodeler.
Who to call
- Building dept
- 618-624-4500
- Official
- Not published. Any site printing a name here is guessing.
- Permits
- Department page
How O'Fallon compares with the rest of St. Clair County
Same county, same climate, same houses. Not the same rules.
| Place | Permit to re-side | Permit for a window | Window must meet |
|---|---|---|---|
| O'Fallon | Not published | Not published | — |
| Belleville | Yes | Yes | — |
| Fairview Heights | Yes | Yes | — |
| Swansea | No | No | — |
Work we have done in O'Fallon
None logged in O'Fallon yet. When there is one it goes here, with the address block and what was actually done to it. An empty section is better than a number you cannot check.
Where these facts came from
Everything on this page about O'Fallon was read off a published source. Where a question has no published answer we have said so rather than filling the gap.
Sources: ofallon.org · ofallonillinois.org · codelibrary.amlegal.com · codelibrary.amlegal.com · codelibrary.amlegal.com · codelibrary.amlegal.com · codelibrary.amlegal.com · cdb.illinois.gov · cdb.illinois.gov · cdb.illinois.gov · regulations.justia.com · regulations.justia.com · law.justia.com · law.cornell.edu · energysense.uillinois.edu
Windows or siding in O'Fallon?
Tell us the address. We look up what the city requires before we work out a price.
Tell us about the house
We answer the phone. If we miss you, we call back.