In Unincorporated St. Louis County, the 2015 IRC is in force. We replace and repair roofs here and inspect after hail, starting with a free, photographed inspection.
This page covers the parts of the county that are not inside a city — where the county, not a municipality, runs building and permits. The Census does not publish population or housing totals for that remainder on its own, so this page quotes none for it: the county-wide figures further down include every municipality as well.
Outside any city's limits, building permits in St. Louis County come from the county's Department of Transportation and Public Works rather than a city hall. The county publishes its own Residential Re-Roofing Checklist and Guide, setting out what it expects on a re-roof — worth asking any roofer you are considering whether they work to it. Some cities send their residents to the county as well: Manchester, for one, directs residents to St. Louis County for building permits.
No completed roof in Unincorporated St. Louis County is logged in our job records yet.
Population and housing figures for this area are countywide St. Louis County totals, covering every municipality plus the unincorporated land. The county's Historic Buildings Commission keeps a countywide National Register list, but it lists districts under specific municipalities rather than the unincorporated area as a whole.
For St. Louis County as a whole — every city in it as well as the unincorporated land — the Census Bureau counts 446,192 homes, with a median year built of 1969. 43,354 of them (10%) went up before 1940 and 46,854 (11%) in 2000 or later. The 1960s were the busiest decade, adding 82,127 of today's homes (18%).
Missouri's Department of Commerce and Insurance puts the useful life of a roof at usually about 25 years. By that measure, 89% of St. Louis County's homes — the 399,338 built before 2000 — are past their first roof; 234,740 of them (53%) predate 1970, old enough for two replacements already. Homes from the 2000s (27,989 in St. Louis County) are reaching their first replacement, while the 18,865 built since 2010 are mostly still on the roof they were built with. At that age it pays to know whether the last roof was torn off or laid over the one before it, because a second layer hides the deck.
Detached single-family houses make up 72% (321,187); attached houses and townhouses 5% (20,308). 53,853 homes (12%) sit in two- to nine-unit buildings and 49,107 (11%) 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 1,546 mobile homes, which are a different kind of roof job. Owners live in 69% of the 413,849 occupied homes. Read together, those figures point toward full tear-offs on houses past two roof lives and flat and low-slope sections, which turn up more on attached and multi-unit buildings.
| Built | Homes | Share | |
|---|---|---|---|
| Before 1940 | 43,354 | 10% | |
| 1940s | 28,196 | 6% | |
| 1950s | 81,063 | 18% | |
| 1960s | 82,127 | 18% | |
| 1970s | 71,197 | 16% | |
| 1980s | 53,584 | 12% | |
| 1990s | 39,817 | 9% | |
| 2000s | 27,989 | 6% | |
| 2010s | 15,700 | 4% | |
| 2020 or later | 3,165 | 1% |
Census ACS 2020–2024, tables B25034, B25035, B25024 and B25003: 446,192 homes, 413,849 occupied. Survey estimates.
NOAA’s Storm Prediction Center logged 150 reports of hail 1 inch or larger in St. Louis County as a whole from 2016 through 2025, on 34 different days. 42 of them were 1.75 inches or larger. The largest, 2.5 inches, came on May 16, 2025. The most recent was 2 inches on May 19, 2025. Counts follow people as much as storms, since every report is a spotter’s or a resident’s.
A bruised shingle can look fine for a season or two, which is why a storm inspection after a date like these is worth having.
Outside any city's limits, St. Louis County Public Works sets the rule. Its re-roofing checklist says no building permit is needed for a like-for-like replacement of asphalt shingles on a roof sloped 4:12 or steeper, unless the job changes something: a permit is required when the slope is under 4:12, when more than 25% of the roof sheathing must be replaced, when the new covering is a different material, or when old board sheathing has to be replaced with structural panels. Work that needs no permit still has to meet the county's re-roofing code.
Unincorporated St. Louis County enforces the 2015 IRC. The county's re-roofing checklist lists the 2015 International Residential Code, adopted with county amendments by Ordinance 27,654.
The published number is 314-615-5184. Unincorporated St. Louis County does not publish the building official's name, so this page does not name one. Plenty of sites will show you one anyway. The department page is here.
Unincorporated St. Louis County shares the metro's figures: 115 mph design wind, 20 psf ground snow. The code guide explains both.
Also in St. Louis County:
| City | Re-roof permit | Code | Median built |
|---|---|---|---|
| Unincorporated St. Louis County | Conditional | 2015 IRC | — |
| Affton | Conditional | 2015 IRC | 1958 |
| Ballwin | Yes | 2015 I-Codes (2024 I-Codes proposed for 2026) | 1976 |
| Brentwood | Not published | 2024 IRC | 1956 |
| Chesterfield | Not published | 2015 IBC / 2015 IRC | 1982 |
| Clayton | Not published | 2021 IRC | 1954 |
| Creve Coeur | Not published | 2009 IRC | 1980 |
All 21 St. Louis County cities side by side →
Outside any city's limits, St. Louis County Public Works sets the rule. Its re-roofing checklist says no building permit is needed for a like-for-like replacement of asphalt shingles on a roof sloped 4:12 or steeper, unless the job changes something: a permit is required when the slope is under 4:12, when more than 25% of the roof sheathing must be replaced, when the new covering is a different material, or when old board sheathing has to be replaced with structural panels. Work that needs no permit still has to meet the county's re-roofing code.
Unincorporated St. Louis County enforces the 2015 IRC. The county's re-roofing checklist lists the 2015 International Residential Code, adopted with county amendments by Ordinance 27,654.
Not yet: no completed roof in Unincorporated St. Louis County 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: manchestermo.gov · stlouiscountymo.gov · stlouiscountymo.gov · en.wikipedia.org · censusreporter.org · stlouiscountymo.gov · data.census.gov · www.spc.noaa.gov. Rules and staff change; check with the jurisdiction.
