Roof replacement, leak repair and hail & storm damage for homes in O'Fallon. In O'Fallon, a re-roof needs a permit and the median home was built in 2000. It starts with a free inspection that photographs every slope.
O'Fallon runs to about 30.51 square miles and roughly 94,074 people. It sits about 31 miles northwest of downtown St. Louis. The community dates back to 1912. We cover ZIP codes 63366 and 63368.
No completed roof in O'Fallon is logged in our job records yet.
O'Fallon has one of the youngest housing stocks in the metro, reflecting fast growth from 91,316 residents (2020 census) to an estimated 94,074 by 2023.
O'Fallon was first settled in 1856 and incorporated in 1912, and its housing is dominated by rapid recent growth. The 1907-era St. Mary's Institute building, listed on the National Register in 2007, is a rare holdover from an earlier era among the newer subdivisions.
Most newer homes in O'Fallon have OSB decking, architectural shingles and a real ridge vent, so they start ahead. What varies is the grade of shingle: much of the 2000s building used builder-grade product whose warranty on paper outlasts its working life, and those roofs are wearing out now. Hail is the other variable. A young roof can still be bruised, and a damaged mat may look perfect from the driveway for a couple of years before it starts to fail, so a roof never checked after a storm is due a look.
By the Census Bureau's estimate there are 36,206 homes in O'Fallon, with a median year built of 2000. 280 of them (1%) went up before 1940 — 41st of 48 places on this site for pre-1940 share — and 18,018 (50%) in 2000 or later. The 1990s were the busiest decade, adding 11,382 of today's homes (31%). (St. Charles County as a whole: 2% before 1940.)
The rule of thumb from Missouri's Department of Commerce and Insurance is a useful life of usually about 25 years for a roof. By that measure, 50% of O'Fallon's homes — the 18,188 built before 2000 — are past their first roof; 2,219 of them (6%) predate 1970, old enough for two replacements already. The 10,946 homes from the 2000s are where first replacements come up now, while the 7,072 built since 2010 are mostly still on the roof they were built with.
By building type: 27,212 detached houses (75%), 3,284 attached (9%). 1,725 homes (5%) sit in two- to nine-unit buildings and 2,768 (8%) in buildings of ten units or more, where the roof is usually a landlord's or an association's decision. The count also takes in 1,217 mobile homes, which are a different kind of roof job. Owners live in 81% of the 35,471 occupied homes. On a housing mix like this, the likely work is first replacements on 2000s builder-grade shingles and hail checks on newer roofs that look fine from the driveway.
| Built | Homes | Share | |
|---|---|---|---|
| Before 1940 | 280 | 1% | |
| 1940s | 123 | 0% | |
| 1950s | 666 | 2% | |
| 1960s | 1,150 | 3% | |
| 1970s | 1,119 | 3% | |
| 1980s | 3,468 | 10% | |
| 1990s | 11,382 | 31% | |
| 2000s | 10,946 | 30% | |
| 2010s | 5,726 | 16% | |
| 2020 or later | 1,346 | 4% |
Census ACS 2020–2024, tables B25034, B25035, B25024 and B25003: 36,206 homes, 35,471 occupied. Survey estimates.
NOAA’s Storm Prediction Center logged 14 reports of hail 1 inch or larger within 5 miles of O’Fallon’s center from 2016 through 2025, on 8 different days. 1 of them was 1.75 inches or larger. The largest, 2 inches, came on May 16, 2025, about 4.5 miles southeast of the center. Counts follow people as much as storms, since every report is a spotter’s or a resident’s.
| Latest reports | Size | From center |
|---|---|---|
| May 16, 2025 | 2 inches | 4.5 mi SE |
| May 16, 2025 | 1.25 inches | 4.4 mi SE |
| May 16, 2025 | 1 inch | 3.7 mi SE |
| May 16, 2025 | 1 inch | 3.3 mi S |
| May 16, 2025 | 1 inch | 1 mi S |
Hail damage rarely shows from the ground; a storm inspection photographs each slope so you know either way.
A permit is required for re-roofing. The city publishes a 'Residential Re-roofing Requirements' guide.
O'Fallon does not publish the code edition it currently enforces, so this page does not name one. Editions across the metro run from the 2006 IRC to the 2024 IRC — worth asking any contractor which one they are building to.
The published number is 636-379-5660. The building official on record is Nathan Lacey, Building Official (636-379-5597, nlacey@ofallonmo.gov). The department page is here.
Wind 115 mph (ultimate) and ground snow 20 psf, the same across the metro; see the roofing code guide for what they govern.
O'Fallon borders Lake St. Louis and St. Peters. Our pages for them:
Also in St. Charles County:
| City | Re-roof permit | Code | Median built |
|---|---|---|---|
| O'Fallon | Yes | Not published | 2000 |
| Lake St. Louis | Not published | 2021 Construction Codes | 2000 |
| St. Peters | Not published | 2021 IRC | 1988 |
| Cottleville | Not published | 2021 IRC | 2012 |
| St. Charles | No | 2021 IRC | 1986 |
| Wentzville | Not published | 2015 I-Codes | 2008 |
All 6 St. Charles County cities side by side →
A permit is required for re-roofing. The city publishes a 'Residential Re-roofing Requirements' guide.
Median year built 2000, by the Census Bureau's 2020–2024 estimates. Of 36,206 homes, 18,188 were built before 2000 and 280 before 1940, so most roofs in O'Fallon are not the first one the house has had.
14 reports of 1-inch-plus hail fell within 5 miles of O'Fallon between 2016 and 2025, the biggest 2 inches on May 16, 2025 (NOAA Storm Prediction Center).
The building official on record is Nathan Lacey, Building Official. The department's own number is on this page, beside its name.
Not yet: no completed roof in O'Fallon is in our job records, so this page shows no job count.
Researched 2026-09-09; housing, Census ACS 2020–2024; hail, NOAA SPC. Sources: www.ofallon.mo.us · www.ofallonmo.gov · codes.iccsafe.org · ecode360.com · en.wikipedia.org · www.bestplaces.net · data.census.gov · www.spc.noaa.gov. Rules and staff change; check with the jurisdiction.
