What does attic insulation cost in St. Louis?
In St. Louis, the two numbers that move an attic budget most are the rebate you qualify for and whether the attic holds vermiculite.12
National average
$1,000–$2,700
HomeGuide's national average range to insulate an attic; the national average is $1,800.3
Rebate math for a 1,000 sq ft attic
| Program | Rate | On 1,000 sq ft |
|---|---|---|
| Ameren PAYS: attic insulation | $0.20/sq ft | $200 |
| Ameren PAYS: air sealing | $0.06/sq ft | $60 |
| Spire (Missouri tariff, eff. Oct. 24, 2025) | $0.40/sq ft, max $750 | $400 |
Our arithmetic on the published rates.14 The Spire cap is reached at 1,875 sq ft. Confirm current terms with Spire.
Pricing R-38, the local rebate target
Both rebates above require at least R-38.14 Nationally, blown-in insulation to R-38 costs $840 to $1,500 per 1,000 sq ft, and to R-49, $1,100 to $1,900.5 Ameren's rebate specifically requires blown-in cellulose.1
Ready to price your St. Louis attic?
One short form connects you with one independent local insulation contractor who serves your area. Free for homeowners, no obligation.
Get my free quoteTakes under a minuteIf it's vermiculite
Asbestos removal runs $10 to $25 per square foot nationally, so a 1,000-square-foot attic could be $10,000 to $25,000 before any new insulation (our arithmetic).3 The EPA says further testing isn't necessary to take precautions, since you should assume vermiculite contains asbestos; if you do test, HomeGuide puts testing at $250 to $850.23
Other national line items
- Air sealing: $350 to $3,000.3
- Removing old (non-hazardous) insulation: $1 to $2 per sq ft.3
- Attic cleaning: $100 to $500 or more.3
- Pest inspection before insulating: $40 to $150.3
Common questions
How much does attic insulation cost in St. Louis?
No local survey exists. HomeGuide's national average range is $1,000 to $2,700, and blown-in insulation to R-38 costs $840 to $1,500 per 1,000 square feet nationally.
How much is the Ameren PAYS attic rebate?
$0.20 per square foot in 2026, or $200 on 1,000 square feet, plus $0.06 per square foot for air sealing.
What does vermiculite removal cost?
HomeGuide lists asbestos removal at $10 to $25 per square foot nationally.
Do I need to test vermiculite for asbestos?
The EPA says testing isn't necessary to take precautions: assume it contains asbestos and don't disturb it.
General information summarized from the public sources listed below. It isn't professional, engineering or legal advice. Codes and programs change; confirm current requirements with your local building department or utility before you start.
Sources
- Ameren Missouri, "Pay As You Save Program" rebate sheet, valid Jan. 1–Dec. 31, 2026 (PDF)
- U.S. EPA, "Protect Your Family from Asbestos-Contaminated Vermiculite Insulation"
- HomeGuide, "Attic Insulation Cost" (national figures, Jan. 13, 2026)
- Spire Missouri tariff P.S.C. MO. No. 9, sheet R-30, Residential High Efficiency Rebate Program (issued Sept. 24, 2025; effective Oct. 24, 2025; Missouri PSC EFIS, PDF)
- HomeGuide, "Blown-In Insulation Cost" (national figures, Nov. 5, 2025)