Insulation in Kirkwood, Missouri

Insulation and air sealing in Kirkwood

Kirkwood runs to about 9.2 square miles and roughly 29,461 people. It sits about 12 miles west of downtown St. Louis. That is roughly 12,978 housing units. The community dates back to 1853. We cover ZIP code 63122.

Our job history shows nothing in Kirkwood so far. Plenty of sites will show you a number here anyway.

The housing stock in Kirkwood

The typical home in Kirkwood dates to around the early-1960s. Postwar building here often meant three or four inches of fiberglass and no attempt at air sealing. If nobody has touched it since, that is what is still up there.

Kirkwood's housing spans from 1850s-era districts (Jefferson-Argonne, West Argonne, North Taylor) through a 1920s district (Central Place) to 1950s Mid-Century Modern subdivisions (Barrett Brae, Craig Woods, Sugar Creek Ranch).

We work across Kirkwood rather than one corner of it — Barrett Brae, Central Place, Craig Woods, Jefferson-Argonne, Meramec Highlands, North Taylor, Savoy, Sugar Creek Ranch and West Argonne included. Construction and vintage change between them, sometimes by thirty years and a whole different framing method, which decides whether a wall can be dense-packed at all.

Kirkwood has a city Landmarks Commission and 9 locally designated historic districts (spanning the 1850s to the 1950s, including three Mid-Century Modern districts), 4 of which are also individually listed on the National Register, plus 85 designated individual landmarks.

Kirkwood homes in the Census numbers

The Census Bureau estimates 12,978 homes in Kirkwood. 2,144 of them (17%) went up before 1940 — 9th of 44 places on this site for pre-1940 housing. The 1950s were the busiest decade, adding 2,623 of today's homes (20%); 70% predate 1980 and 19% were built in 2000 or later. For St. Louis County as a whole the pre-1940 share is 10%, so Kirkwood sits above it.

Of 11,992 occupied homes, 75% heat with utility gas and 22% with electricity. Electric heat here is less common than across the county (23%), and ranks 38th of 44 on this site. That is why the assessment asks how the house is heated: the fuel and the name on the utility bill decide which program, if any, can pay toward the work.

77% of occupied homes are owner-occupied and 75% of all homes are single-family detached houses. Read together, those numbers point toward an attic top-up over postwar fiberglass.

12,978 homes, Census ACS 2020–2024 (B25034, B25040, B25003); 11,992 occupied.

Sealing comes first in Kirkwood

5,587 of Kirkwood's 12,978 homes (43%) date from 1950 through 1979. The leaks in houses of that era repeat: nothing over the top plates, wire and pipe holes left open, an unsealed hatch, a bath fan venting into the attic, and in ranches and split-levels, heat lost at the garage ceiling and over cantilevered floors. Sealing the plates, holes and fans comes before any more fiber, and it is usually a day's work, not a renovation.

What the energy code requires in Kirkwood

Kirkwood enforces the 2021 IECC. Kirkwood Code Section 5-6d adopts the 2021 Energy Conservation Code, as modified, as the official City of Kirkwood Energy Conservation Code, by Ordinance No. 10921 dated December 18, 2025. Section 5-2 adopts the 2021 International Building Code, the 2021 International Residential Code and the 2021 International Existing Building Code, all as modified, by Ordinance Nos. 10918, 10919 and 10934 dated December 18, 2025 and January 22, 2026. The modifications to each code are held in a separate ordinance document on file in the City Clerk's office and are not printed in the online code.

Under that edition the required attic value for new work here is R-60, and walls R-30, or R-20 cavity plus R-5 continuous, or R-13 cavity plus R-10 continuous, or R-20 continuous. For comparison, the Department of Energy recommends R60 for an uninsulated attic in climate zone 4A, where Kirkwood sits, and R49 where there are already a few inches up there.

2021 IECC Table R402.1.3, climate zone 4 (except marine), as reproduced in the U.S. Department of Energy / PNNL Building America Solution Center comparison of 2009-2021 IECC and IRC minimum insulation requirements. Kirkwood adopted the 2021 code 'as modified' and the modifications are not published online, so a job should be checked against the clerk's copy.

Do you need a permit to insulate here?

There is no published answer for Kirkwood. Neither the permit-required list nor the exemption list mentions insulation or air sealing at all. The Building Division states that permits are issued and inspections required for all new construction and for the remodeling and repair of existing structures, but it does not name insulation. Insulation does not appear in the division's brochure list or in the headings of the Chapter 5 fee schedule sections (5-208 through 5-223), which cover construction permits, mechanical equipment, fireplaces, HVAC replacement, inspections, plumbing and electrical fees. That silence is not permission and it is not a prohibition. We settle it with a phone call before the crew is scheduled.

Permits and inspections in Kirkwood

The published number is 314-822-5823. The department page is here.

Permitting is on us, not on you.

Rebates a Kirkwood homeowner can actually use

Most Kirkwood addresses are Ameren Missouri electric customers, and Ameren Missouri pays toward insulation through Pay As You Save: $0.20 per square foot on the attic and $0.06 per square foot on air sealing in the 2026 program year, with the rest of the cost recovered through the electric bill. It counts only when the attic is at R-20 or below beforehand and R-38 or more afterward, when air sealing cuts measured leakage by 20 percent, and when the household has lived there for the past year; for income-eligible households, CommunitySavers can include attic insulation at no charge. Income-qualified households can apply to Community Action Agency of St. Louis County (CAASTLC) (314-863-0015) for free weatherization instead. The full program rules are on the St. Louis County page and in the rebate guide.

Nearby

Kirkwood borders Des Peres, Frontenac, Glendale, Huntleigh, Oakland and Warson Woods. These are the ones we also cover, each with its own energy code and permit rule:

Elsewhere in St. Louis County we also cover:

How Kirkwood compares with its neighbors

Missouri sets none of this at state level. Across the 7 places in this table there are 4 different adopted editions (2015 IECC, 2018 IRC ch. 11, 2021 IECC and 2024 IECC), and 1 of the 7 publishes a permit rule for insulation.

All 21 St. Louis County jurisdictions side by side →

Common questions about insulation in Kirkwood

Code and permit facts checked September 10, 2026, rebates October 24, 2026; housing: Census ACS 2020–2024. Sources: ecode360.com (2, 3) · kirkwoodmo.org (2, 3, 4) · basc.pnnl.gov · en.wikipedia.org · censusreporter.org · bestplaces.net · ameren.com (2, 3, 4) · energystar.gov · data.census.gov. These change; confirm with the building department at 314-822-5823 or Kirkwood Electric first.