State facts
Iowa: homes, climate zones and who licenses the work
Iowa has 1.4 million housing units. 61.6% were built before 1980, and the median year built is 1972. 71.7% of occupied homes are lived in by their owners.
How old the homes are
Iowa housing units, by year built
Layers drawn to scale
Age changes what applies to a house. In general, anyone paid to do work that disturbs painted surfaces in a home built before 1978 must be certified in lead-safe work practices under the EPA's Renovation, Repair and Painting Rule, which Iowa Department of Inspections, Appeals, and Licensing (DIAL) administers in Iowa.
How homes are heated
How homes in Iowa are heated
Main heating fuel, share of 1.3 million occupied homes
- Utility gas 60.2%
- Electricity 24.4%
- Propane or other tank gas 12.6%
- Wood 1.1%
- Other fuel 0.7%
- No fuel used 0.6%
- Fuel oil or kerosene 0.3%
- Solar energy 0.1%
- Coal or coke <0.1%
Climate and building zones
The 2021 International Energy Conservation Code assigns every county a climate zone from 1 to 8 and a moisture regime: A for moist, B for dry, C for marine. Zones 7 and 8 have no letter. Here is how Iowa's residents divide among them, by the county they live in.
| IECC 2021 zone | Share of residents | Counties |
|---|---|---|
| 5A | 89.1% | 84 |
| 6A | 10.9% | 15 |
ENERGY STAR rates windows, doors and skylights for four climate zones of its own. All of Iowa falls in the Northern zone.
By NOAA's 1991–2020 climate normals, counties here average 147 days a year with a low of 32°F or colder, weighted by where people live. The range runs from 122 days in the mildest county to 173 in the coldest.
- SEER2 Requirements by State: What a New AC Must Meet
- What Size AC Do I Need? How a Load Calculation Answers It
- Do Heat Pumps Work in Cold Weather? What to Check Before Buying
- No Heat in Winter: How to Stay Safe Until the Furnace Is Fixed
- Ice Dams: Why They Leak Into Ceilings and How to Stop Them
- Crawl Space Moisture: Vented vs. Sealed Crawl Spaces
- Condensation on the Inside of Windows: Causes and Fixes
Flood risk and flood insurance
0.5% of residential structures in Iowa carry a National Flood Insurance Program policy: 6,602 policies, in FEMA's count as of August 3, 2026.
In FEMA's National Risk Index, none of Iowa's 99 counties rates high or very high for riverine flooding, coastal flooding or hurricanes.
Fire ants and termites
No county in Iowa is inside the federal imported fire ant quarantine.
Who licenses the work in Iowa
Before anyone starts work, check the license with the agency below. Where the state does not license a trade, cities and counties may; ask the one where the house is.
- Pest control A business that applies pesticides to the property of others is licensed as a commercial pesticide applicator (each location separately), and each individual who applies pesticides for it must be a certified applicator. Agency: Iowa Department of Agriculture and Land Stewardship, Pesticide Bureau. Look up a license. Who to call about pest control.
- Heating and cooling Contractors providing HVAC, refrigeration, sheet metal, hydronic or other mechanical services must hold a state contractor license from the board and register with DIAL; individual mechanical workers hold apprentice, journey, master or specialty licenses. Agency: Iowa Plumbing and Mechanical Systems Board, Department of Inspections, Appeals, and Licensing. Look up a license. Who to call about heating and cooling.
- Window replacement and other home improvement Construction contractors who earn at least $2,000 a year from construction must register with the state; this is a registration, not a skills license. Agency: Iowa Department of Inspections, Appeals, and Licensing, Contractor Registration. Look up a license. Who to call about window replacement.
- Mold remediation We found no statewide license for this work in official sources. Cities and counties may license it; ask the one where the house is. Who to call about water damage and mold.
Checked 2026-09-29. Licensing rules change; the agency's own page is the authority.
Sources
- U.S. Census Bureau American Community Survey 2020–2024 5-year estimates, tables B25034, B25035, B25040 and B25003 data.census.gov
- Pacific Northwest National Laboratory Guide to Determining Climate Zone by County: Building America and IECC 2021 Updates basc.pnnl.gov
- U.S. Department of Energy Prototype Building Models (climate zones 1–8 and moisture regimes A, B, C) energycodes.gov
- ENERGY STAR Climate zones by county for windows, doors and skylights energystar.gov
- NOAA National Centers for Environmental Information U.S. Climate Normals 1991–2020, annual and seasonal ncei.noaa.gov
- Federal Emergency Management Agency OpenFEMA NFIP Residential Penetration Rates (as of 2026-08-03) fema.gov
- Federal Emergency Management Agency National Risk Index, county ratings fema.gov
- USDA Animal and Plant Health Inspection Service Imported fire ant quarantine map aphis.usda.gov
- Electronic Code of Federal Regulations 7 CFR part 301, subpart P, Imported Fire Ant ecfr.gov
- Iowa Department of Agriculture and Land Stewardship, Pesticide Bureau iowaagriculture.gov iowaagriculture.gov
- Iowa Plumbing and Mechanical Systems Board, Department of Inspections, Appeals, and Licensing dial.iowa.gov dial.iowa.gov
- Iowa Department of Inspections, Appeals, and Licensing, Contractor Registration dial.iowa.gov dial.iowa.gov
- Iowa Department of Inspections, Appeals, and Licensing (DIAL) epa.gov epa.gov
- Iowa Department of Inspections, Appeals, and Licensing (DIAL) dial.iowa.gov dial.iowa.gov