What it actually takes to insulate a house in Pacific — what the city publishes about energy code and permits, what it does not, the rebate your address qualifies for, and how old the housing here really is.
Pacific runs to about 6.7 square miles and roughly 7,414 people. It sits about 30 miles southwest of downtown St. Louis. There are around 3,218 housing units here, and the great majority of them are heated and cooled through a ceiling nobody has ever sealed. The community dates back to 1859. We cover ZIP code 63069.
We have not logged a completed job in Pacific yet. We would rather say so than put a number on this page that is not real.
The typical home in Pacific dates to around the early-1990s. Houses of this vintage usually got batts or blown fibre at whatever the standard of the day was, which is well short of what is recommended now. Most are one top-up away from being right.
Downtown core has brick commercial buildings restored from the late 1800s along First and St. Louis Streets, plus 1930s-40s Route 66 motor-court era structures (Red Cedar Inn, Al-Pac Motel, Beacon Court); typical home dates to around 1991, reflecting later 20th-century suburban infill around that older core.
Meramec River flooding is documented in Pacific in 1895 and 1915, and an 1891 fire destroyed all buildings on St. Louis Street between First and Columbus; the city also straddles the Franklin/St. Louis county line.
Housing from this stretch in Pacific 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.
Pacific has no residential energy code in force. Pacific deleted Chapter 11 of the IRC in its entirety and adopts no edition of the IECC, so no residential energy code is in force here. Pacific adopts the 2018 International Residential Code, in Section 500.152, by Ordinance No. 3349 of 12-20-2022, following Ord. Nos. 2249, 2542 and 3013. Section 500.153(40) then states Chapter 11, Energy Efficiency - Delete in its entirety. On the commercial side, Article II adopts the 2018 International Building Code, most recently by Ord. No. 3348 of 12-20-2022, and deletes IBC Section 101.4.6 Energy. Chapter 500 contains no adoption of any edition of the International Energy Conservation Code. The result is that Pacific has no adopted residential energy code. That does not make insulation optional — it makes the specification a conversation between you and whoever you hire, with nothing behind it but their word. It is a good reason to ask for the R-value in writing.
Pacific publishes no answer either way. Insulation and air sealing appear on neither the permit-required list nor the exempt list. 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 code's Article II notes only that exception 2 of IBC Section 105.2 was deleted; insulation is not mentioned in the readable portions of Chapter 500. We confirm it with the department before we start and pull whatever is needed. We would rather write that here than guess on your behalf.
The published number is 636-271-0500. The department page is here.
Permitting is on us, not on you.
Pacific 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. Franklin County is served by Jefferson-Franklin Community Action Corp. (JFCAC) under the Missouri low-income weatherization program — 636-789-2686, 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.
Pacific sits in all eight counties are iecc 2021 climate zone 4, mixed-humid, which is the zone that has to be defended in both directions: 4,433 heating degree days and 1,713 cooling degree days a year at Lambert. That is what every R-value on this page is sized for. The energy code and rebate guide works through the rest of the figures.
Pacific borders Eureka. These are the ones we also cover, each with its own energy code and permit rule:
Elsewhere in Franklin 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. |
|---|---|---|---|---|
| Union | Not published | — | Not published | 636-583-1805 |
| Washington | Not published | — | Not for an attic top-up | 636-390-1000 |
Free assessment, a measured R-value, and photos you keep either way.
None. Pacific deleted Chapter 11 of the IRC in its entirety and adopts no edition of the IECC, so no residential energy code is in force here. The Department of Energy recommends R60 for an uninsulated attic in this climate zone, which is the number worth building to whether or not anyone is enforcing it.
Nobody can tell you from a website, including this one. Pacific lists neither insulation nor air sealing as permit work, and does not exempt it either. We ring the department, get an answer for your specific job, and pull anything it needs.
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 Pacific dates to around the early-1990s. Houses of this vintage usually got batts or blown fibre at whatever the standard of the day was, which is well short of what is recommended now. Most are one top-up away from being right. 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 Pacific, 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 Pacific 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: ecode360.com · ecode360.com · ecode360.com · ecode360.com · pacificmo.gov · pacificmo.gov · pacificmo.gov · ecode360.com · en.wikipedia.org · censusreporter.org · city-data.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.