Des Peres enforces its own energy code edition, which sets its own attic number. Here is that number, whether the work needs a permit, which utility programme pays toward it, and what a house of this vintage usually turns up.
Des Peres runs to about 4.3 square miles and roughly 9,170 people. It sits about 14 miles west of downtown St. Louis. That is roughly 3,331 housing units, and the attic above almost all of them is the cheapest thing in the house left to fix. The community dates back to 1934. We cover ZIP code 63131.
Our job history shows nothing in Des Peres so far. Plenty of sites will show you a number here anyway.
The typical home in Des Peres dates to around the mid-1970s. Postwar building here often meant three or four inches of fibreglass and no attempt at air sealing. If nobody has touched it since, that is what is still up there.
Mostly built in the 1970s (nearly 30% of homes).
That includes Dougherty Lake. Housing age and construction shift across Des Peres, sometimes by decades within a few streets, which is why we look in the attic before quoting rather than after.
Des Peres was incorporated as a town in 1934. Dougherty Lake was one of its original residential subdivisions, and its City Hall predates incorporation, having originally been built by a neighboring Lutheran church as an orphanage.
Housing from this stretch in Des Peres generally got a real attempt at insulation — a real layer in the attic, batts in the walls — so the argument here is rarely about starting from nothing. It is about the gap between what was standard then and what is recommended now, and about the parts nobody insulated at all. Recurring finds: batts stuffed into the rim joist rather than sealed, insulation missing entirely above a cathedral or tray ceiling, soffit vents blocked solid by insulation blown over them with no baffles, and can lights punched straight through the ceiling plane. A house from this era is usually a top-up plus a day of sealing, not a rebuild.
Des Peres enforces the 2018 IRC Chapter 11 (Energy Efficiency). Ordinance 2873, the city's 2018 code adoption, adopts the 2018 International Building Code, the 2018 International Residential Code, the 2018 International Swimming Pool and Spa Code, the 2018 International Existing Building Code, the 2018 International Fire Code and the 2018 International Property Maintenance Code. It does not adopt an International Energy Conservation Code of any edition. The ordinance's amendments touch Sections 112.4, 302.4, 304.14, 602.3 and 602.4 and state that no other sections are altered, so Chapter 11, Energy Efficiency, of the 2018 IRC is in force as written. The Missouri state code database likewise lists Des Peres with the 2018 IRC and 2018 IBC and no separate energy code.
Under that edition the required attic value for new work here is R-49, and walls R-20, or R-13 plus R-5 continuous. For comparison, the Department of Energy recommends R60 for an uninsulated attic in this climate zone and R49 where there are already a few inches up there.
Chapter 11 of the 2018 IRC carries the same envelope requirements as Table R402.1.2 of the 2018 IECC. For climate zone 4 except marine that is ceiling R-49 and wood frame wall R-20 or R-13+5, per the PNNL Building America Solution Center IECC and IRC insulation table and NAIMA's 2018 IECC climate zone 4 summary.
There is no published answer for Des Peres. Neither the permit-required list nor the exemption list mentions insulation or air sealing at all. That is the normal state of affairs across this metro — only a handful of the 45 jurisdictions on this site say anything about it at all. The Permit Requirements page lists residential building, pool, fence and demolition permits, commercial building, sign and occupancy permits, and grading, land disturbance and subdivision permits. Insulation, air sealing and weatherization are not named on any of those lists, and the city directs specific questions to the Public Works Department. That silence is not permission and it is not a prohibition. We settle it with a phone call before the crew is scheduled.
Neither the Building Division page nor the permit requirements page states a contractor registration or licensing requirement.
The published number is 314-835-6130. The department page is here.
Permitting is on us, not on you.
Des Peres is on the Missouri side, which for most addresses means Ameren Missouri — and Ameren Missouri does not hand out a straight per-square-foot insulation rebate the way its Illinois sister utility does. What it runs instead is Pay As You Save: a free home energy assessment, then the work installed by a programme partner and paid back through a fixed monthly charge on the electric bill, which cannot exceed 80% of the estimated monthly saving, so the bill still comes down while it is being repaid. No loan and no credit check.
Published incentives inside that programme for the 2026 programme year are $0.20 per square foot on ceiling and attic insulation, $0.06 per square foot on air sealing, and 50% of costs up to $250 per home on duct sealing. Each one has a condition attached, and they matter:
Ameren Missouri also runs CommunitySavers, which installs attic insulation at no charge for income-eligible households. The program operates through December 31, 2026; incentives are dependent on available funds.
Spire, the gas utility on this side, lists furnace, water heater and thermostat rebates on its Missouri rebate page rather than a standalone insulation one. Its published route to attic insulation and air sealing is the same on-bill Pay As You Save programme, which it co-delivers, plus income-based weatherization. If you are a Spire customer it is worth ringing them to ask what is open this year, because that page moves.
If the household income qualifies, the work can be free rather than discounted. St. Louis County is served by Community Action Agency of St. Louis County (CAASTLC) under the Missouri low-income weatherization program — 314-863-0015, details here.
One more, by its absence: the federal 25C credit, which covered 30% of insulation and air sealing up to $1,200 a year, ended for anything placed in service after 31 December 2025. Work finished on or before that date is still claimed on that year's return; nothing done in 2026 is. It should not be in your 2026 price, whoever tells you otherwise — the rebate guide has the detail.
Des Peres sits in all eight counties are iecc 2021 climate zone 4 on the same map the Department of Energy uses to write its recommendations, which is why the figure it recommends for an attic here is R60 rather than something borrowed from a national advert. Heating and cooling both matter at this latitude. The energy code and rebate guide sets out the numbers behind it.
Elsewhere in St. Louis County we also cover:
Missouri sets none of this at state level, so the number that was right one municipality over is not automatically right here.
| City | Energy code | Attic R required | Permit to insulate | Building dept. |
|---|---|---|---|---|
| Affton | 2015 IECC | R-49 | Not for an attic top-up | 314-615-5184 |
| Ballwin | Not published | — | Not published | 636-227-2129 |
| Brentwood | 2024 IECC | R-49 | Not published | 314-963-8602 |
| Chesterfield | Not published | — | Not published | 636-537-4000 |
| Clayton | 2021 IECC | R-60 | Not published | 314-290-8463 |
| Creve Coeur | 2015 IECC | R-49 | Not published | 314-872-2500 |
| Ellisville | 2015 IRC ch. 11 | R-49 | Not published | 636-227-9660 |
| Eureka | 2018 IRC ch. 11 | R-49 | Not published | 636-938-5233 |
| Florissant | 2021 IECC | R-60 | Not published | 314-839-7648 |
| Kirkwood | 2021 IECC | R-60 | Not published | 314-822-5823 |
| Manchester | Not published | — | Not published | 314-615-5184 |
| Maryland Heights | 2015 IECC | R-49 | Not published | 314-291-6550 |
| Mehlville | Not published | — | Not for an attic top-up | 314-615-5184 |
| Oakville | 2015 IECC | R-49 | Not for an attic top-up | 314-615-5184 |
| Richmond Heights | 2024 IECC | R-49 | Not published | 314-646-7658 |
| Unincorporated St. Louis County | 2015 IECC | R-49 | Not for an attic top-up | 314-615-5184 |
| Town and Country | 2018 IRC ch. 11 | R-49 | Not published | 314-587-2820 |
| University City | 2018 IECC | R-49 | Not published | — |
| Webster Groves | Not published | — | Not published | 314-963-5300 |
| Wildwood | Not published | — | Not for an attic top-up | 636-458-0440 |
Free assessment, a measured R-value, and photos you keep either way.
The code edition Des Peres enforces sets R-49 for new work. The Department of Energy separately recommends R60 for an uninsulated attic in this climate zone, and R49 where a few inches are already there.
Des Peres has not published a rule for it. In practice that means one call to the building department before the job starts, which is on us rather than on you.
For most addresses here the route is Ameren Missouri's Pay As You Save programme, which publishes $0.20 per square foot on ceiling and attic insulation and $0.06 per square foot on air sealing for the 2026 programme year. Both carry conditions: the attic has to start at R-20 or below and reach at least R-38, and the air sealing has to cut leakage by at least 20 percent. The incentives sit inside tier 4 of the programme and need you to have lived in the home for the past twelve months, and they are recovered through a monthly charge on the electric bill rather than paid as a cheque. Income-eligible households can get attic insulation at no charge through CommunitySavers instead. The federal 25C credit ended for work placed in service after 31 December 2025.
The typical home in Des Peres dates to around the mid-1970s. Postwar building here often meant three or four inches of fibreglass and no attempt at air sealing. If nobody has touched it since, that is what is still up there. That figure is an ACS-derived median republished by housing-data services, not a survey of individual houses.
Not yet. We have no completed job logged in Des Peres, and we would rather say so than put a number on this page that is not real.
Neither state licenses insulation contractors as a trade. In Missouri there is no statewide residential code at all, and registration is imposed city by city — several metro municipalities require a contractor to be registered with them before a permit is pulled. What matters more in practice is utility programme enrolment, because that is what decides whether your rebate is real.
Energy code, permit and department details for Des Peres come from the jurisdiction's own published pages and codified ordinances. Rebate figures come from the utility's own published incentive tables and carry the programme year they were verified in. Housing-age figures are ACS-derived medians republished by housing-data services, so treat them as approximate. Sources: desperesmo.org · desperesmo.org · desperesmo.org · data.mo.gov · basc.pnnl.gov · insulationinstitute.org · desperesmo.org · desperesmo.org · desperesmo.org · en.wikipedia.org · censusreporter.org · point2homes.com · ameren.com · ameren.com · ameren.com · ameren.com · energy.gov. Adopted code editions, department phone numbers and utility rebate amounts all change — confirm with the jurisdiction or the utility before relying on anything here.