State facts
Wisconsin: homes, climate zones and who licenses the work
Wisconsin has 2.8 million housing units. 57% were built before 1980, and the median year built is 1975. 67.8% of occupied homes are lived in by their owners.
How old the homes are
Wisconsin 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 Wisconsin Department of Health Services (Division of Public Health, Lead and Asbestos Section) administers in Wisconsin.
How homes are heated
How homes in Wisconsin are heated
Main heating fuel, share of 2.5 million occupied homes
- Utility gas 64.8%
- Electricity 17.8%
- Propane or other tank gas 11.8%
- Wood 2.7%
- Fuel oil or kerosene 1.4%
- Other fuel 0.8%
- No fuel used 0.6%
- 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 Wisconsin's residents divide among them, by the county they live in.
| IECC 2021 zone | Share of residents | Counties |
|---|---|---|
| 5A | 68.5% | 30 |
| 6A | 31.5% | 42 |
ENERGY STAR rates windows, doors and skylights for four climate zones of its own. All of Wisconsin falls in the Northern zone.
By NOAA's 1991–2020 climate normals, counties here average 150 days a year with a low of 32°F or colder, weighted by where people live. The range runs from 124 days in the mildest county to 194 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 Wisconsin carry a National Flood Insurance Program policy: 8,929 policies, in FEMA's count as of August 3, 2026.
In FEMA's National Risk Index, 2 of 72 counties rate high or very high for riverine flooding.
Fire ants and termites
No county in Wisconsin is inside the federal imported fire ant quarantine.
Who licenses the work in Wisconsin
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 Any business making commercial for-hire pesticide applications needs a Pesticide Business License (PBL) for each location and must employ certified and licensed commercial applicators. Agency: Wisconsin Department of Agriculture, Trade and Consumer Protection (Bureau of Agrichemical Management). Look up a license. Who to call about pest control.
- Heating and cooling A business that installs or services heating, ventilating, or air conditioning equipment must hold a state HVAC Contractor registration. Agency: Wisconsin Department of Safety and Professional Services. Look up a license. Who to call about heating and cooling.
- Window replacement and other home improvement A contractor who obtains a building permit for work on a one- or two-family dwelling must hold a state Dwelling Contractor certification, which requires a bond or insurance and continuing education. Agency: Wisconsin Department of Safety and Professional Services. 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
- Wisconsin Department of Agriculture, Trade and Consumer Protection (Bureau of Agrichemical Management) datcp.wi.gov datcp.wi.gov
- Wisconsin Department of Agriculture, Trade and Consumer Protection (Bureau of Agrichemical Management) datcp.wi.gov datcp.wi.gov
- Wisconsin Department of Safety and Professional Services docs.legis.wisconsin.gov docs.legis.wisconsin.gov
- Wisconsin Department of Safety and Professional Services dsps.wi.gov dsps.wi.gov
- Wisconsin Department of Safety and Professional Services docs.legis.wisconsin.gov docs.legis.wisconsin.gov
- Wisconsin Department of Safety and Professional Services dsps.wi.gov dsps.wi.gov
- Wisconsin Department of Health Services (Division of Public Health, Lead and Asbestos Section) epa.gov epa.gov
- Wisconsin Department of Health Services (Division of Public Health, Lead and Asbestos Section) dhs.wisconsin.gov dhs.wisconsin.gov