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Iowa Counties
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Overview
Iowa has NO mandatory statewide residential building code. Code adoption is local option. State Fire Marshal has limited commercial jurisdiction. Climate Zones 5A (most)/6A (northern). Ice barrier required. 99 counties.
Code Snapshot
Current editions in effect
Plumbing
IAPMO 2021
2021 Edition
Building Code
IBC 2021
2021 Edition
Code
ICC 2015
2015 Edition
Building Code
IEBC Local Adoption
Local Adoption
Energy
IECC 2012
2012 Edition
Energy
IECC-C Local Adoption
Local Adoption
Effective Date: January 1, 2022
Verified: Mar 2026
Jurisdiction Complexity
Iowa is a MODERATE complexity state
Iowa applies state-level code amendments to ICC base codes, with some variation across local jurisdictions.
SimpleModerateComplex
Wind-Borne Debris
Varies by locality →Key Rules & Requirements
Critical regulations for Iowa restoration work
Iowa has the highest average radon levels in the United States. Over 70% of Iowa homes tested exceed the EPA action level of 4 pCi/L. Radon-resistant new construction (RRNC) techniques are strongly recommended statewide and may be required in municipalities that have adopted IRC Appendix F.
Important: Iowa has extremely high radon levels due to glacial till soils rich in uranium-bearing minerals. The statewide average indoor radon level is approximately 8.5 pCi/L - more than double the EPA action level of 4.0 pCi/L. Over 70% of Iowa homes tested exceed the EPA action level. IRC Appendix F provides radon-resistant new construction (RRNC) techniques including: sub-slab depressurization system with 3" or 4" ABS/PVC pipe from aggregate under slab through roof, gas-permeable layer under slab, polyethylene vapor retarder, sealed slab openings and penetrations, and passive stack exhaust. Municipalities that adopt Appendix F make these requirements mandatory. Even where not required, RRNC adds approximately $500-1,500 to construction cost and is strongly recommended.
Iowa is in the heart of Tornado Alley. Design wind speeds are 115 mph statewide per ASCE 7. Ice barrier requirements apply statewide due to history of ice dam formation.
Important: Iowa experiences severe weather including tornadoes, straight-line winds, and significant hail. Design wind speeds per ASCE 7-16 are approximately 115 mph (3-second gust, Risk Category II) throughout the state. Iowa is entirely in the ice barrier required zone per IRC Table R301.2(1), requiring ice barriers at roof eaves extending at least 24 inches inside the exterior wall line. The state is in IECC Climate Zones 5A and 6A, requiring significant insulation levels (R-49 ceiling, R-20+5 or R-13+10 walls). Hail damage is extremely common and contractors should be familiar with hail damage assessment for insurance claims.
Iowa frost depth ranges from 36 inches in southern counties to 48 inches or more in northern counties (Climate Zone 6A). All exterior footings must extend below frost depth. Local jurisdictions specify exact requirements.
Important: Iowa experiences severe winters with sustained freezing temperatures that create deep frost penetration. IRC R403.1.4 requires footings to be placed below the frost line. Iowa frost depths: Southern Iowa (Zone 5A) approximately 36-42 inches; Northern Iowa (Zone 6A) approximately 42-48+ inches. Frost-protected shallow foundations (IRC R403.3) may be used as an alternative where allowed by the local jurisdiction. Foundation walls and footings must be designed for frost heave loads. Crawl spaces and basements are common in Iowa construction due to deep frost lines. Slab-on-grade construction requires insulated frost-protected design or footings to full depth.
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Code Administration
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Climate Zones
Applicable Codes
Key Codes for Restoration Work
Primary codes for residential restoration projects in Iowa
| Code Type | Current Edition | Effective Date | Base Code | Status | Actions |
|---|---|---|---|---|---|
International Building Code 2021 Commercial & Multi-Family | IBC 2021 | Jan 1, 2022 | IBC 2021 w/ amendments | Current | View Details |
International Existing Building Code Commercial & Multi-Family | IEBC Local Adoption | Jan 1, 2024 | IBC 2021 w/ amendments | Current | View Details |
International Energy Conservation Code 2012 Energy Efficiency Standards | IECC 2012 | Jan 1, 2013 | IECC 2012 w/ amendments | Current | View Details |
International Energy Conservation Code (Commercial) Energy Efficiency Standards | IECC-C Local Adoption | Jan 1, 2024 | IECC 2021 w/ amendments | Current | View Details |
International Energy Conservation Code (Residential) Single-Family & Townhomes | IECC-R 2012 | Jan 1, 2013 | IRC 2012 w/ amendments | Current | View Details |
International Residential Code 2021 Single-Family & Townhomes | IRC 2021 | Jan 1, 2022 | IRC 2021 w/ amendments | Current | View Details |
National Electrical Code 2020 (NFPA 70) Building Requirements | NEC 2020 | Jan 1, 2021 | NEC 2018 w/ amendments | Current | View Details |
International Building Code 2021
Commercial & Multi-Family
IBC 2021Details
International Existing Building Code
Commercial & Multi-Family
IEBC Local AdoptionDetails
International Energy Conservation Code 2012
Energy Efficiency Standards
IECC 2012Details
International Energy Conservation Code (Commercial)
Energy Efficiency Standards
IECC-C Local AdoptionDetails
International Energy Conservation Code (Residential)
Single-Family & Townhomes
IECC-R 2012Details
International Residential Code 2021
Single-Family & Townhomes
IRC 2021Details
National Electrical Code 2020 (NFPA 70)
Building Requirements
NEC 2020Details
Effective dates reflect when each code edition was formally adopted by the state. Dates may differ across code types when amendments are adopted in separate rulemaking cycles. Base codes reference the ICC model code edition that serves as the foundation for the state's adopted version. Verify current applicability with your local Authority Having Jurisdiction (AHJ).
Get a jurisdiction-specific code packet
Enter a Iowa ZIP code for exact applicable codes, special zones, and a compliance checklist.
Special Zones
Special Zones
Snow & Ice
Iowa Snow Load Zone
Iowa ground snow loads range from 20 psf in southern counties to 40 psf in northern counties per ASCE 7-22 Figure 7.2-1. Drift loads along parapets and adjacent structures must be designed per ASCE 7-22 Section 7.7. Northern Iowa lake-effect events from the Great Lakes can produce locally higher accumulations.
Flood & Coastal
Iowa Major River Flood Zones AE
Iowa has extensive Zone AE designations along the Mississippi, Missouri, Des Moines, Cedar, and Iowa rivers. The 2008 Cedar Rapids flood was one of the costliest in US history. Many Iowa communities require 1-2 feet of freeboard above BFE. The Iowa Flood Center operates a real-time flood monitoring network for 1,000+ communities.
Wildfire
Iowa Wildland-Urban Interface Areas
Eastern Iowa bluff lands along the Mississippi River and the Loess Hills in western Iowa contain WUI-designated communities. Iowa DNR Forestry Bureau identifies at-risk communities near forested areas. While lower risk than western states, drought conditions can create significant wildfire hazard. IWUIC guidelines apply where locally adopted.
Geologic
Karst Terrain / Driftless Area (Northeast Iowa)
Northeast Iowa's Driftless Area was unglaciated during the last ice age and features extensive karst topography with limestone and dolomite bedrock prone to dissolution. Counties with significant karst features include: Allamakee, Winneshiek, Clayton, Fayette, Delaware, Dubuque, Jackson, Jones, and portions of Howard, Chickasaw, and Buchanan counties. Features include sinkholes, caves, springs, disappearing streams, and underground drainage systems. Iowa Geological Survey has mapped thousands of karst features in the region.
Requirements: Geotechnical investigation recommended prior to construction in mapped karst areas. Site-specific soil borings to identify bedrock conditions, voids, and solution features. Foundation design must account for variable bedrock depth and potential collapse. Stormwater management must consider underground drainage patterns - surface water may enter groundwater directly through sinkholes. Septic systems require special design to prevent groundwater contamination. Deep foundations or soil stabilization may be required over solution cavities. Consult Iowa DNR and Iowa Geological Survey for karst feature maps.
View sourceWind & Hurricane
Tornado Alley - Severe Wind Zone
Iowa is located in the heart of Tornado Alley and averages 50+ tornadoes per year. The entire state is at significant risk for tornadoes, straight-line winds (derechos), severe thunderstorms, and large hail. The 2020 Iowa Derecho (August 10, 2020) produced wind speeds exceeding 140 mph across a 770-mile path through central Iowa, causing over $11 billion in damage. EF3-EF5 tornadoes are not uncommon. Peak severe weather season is April through August.
Requirements: Enhanced wind resistance recommended statewide: roof sheathing attachment with ring-shank nails at 6" o.c. edges (enhanced schedule), hurricane clips/straps at all roof-to-wall connections, continuous load path from roof to foundation. Storm shelters recommended per ICC 500 / FEMA P-320 (safe rooms). Impact-resistant shingles (ASTM D3462 Class 4) recommended for hail resistance. Garage doors should meet DASMA wind-load ratings. Consider impact-resistant windows in high-exposure areas.
View sourceRadon
High Radon Risk Zone (Statewide)
Iowa has the highest average indoor radon levels in the United States. The statewide average is approximately 8.5 pCi/L - more than double the EPA action level of 4.0 pCi/L. Over 70% of Iowa homes tested exceed the EPA action level. All 99 Iowa counties are classified as EPA Zone 1 (highest radon potential). The high radon levels are attributed to Iowa's glacial till soils, which are rich in uranium-bearing minerals, combined with well-sealed homes in cold climate.
Requirements: Radon-resistant new construction (RRNC) techniques per IRC Appendix F / ASTM E1465 strongly recommended statewide: sub-slab depressurization system with 3" or 4" ABS/PVC pipe from gravel layer under slab through roof, gas-permeable aggregate layer (minimum 4" clean gravel) under slab, 6-mil polyethylene vapor retarder over aggregate, sealed slab openings/penetrations, and passive stack exhaust. Post-construction radon testing recommended on every new home. Iowa Department of Public Health maintains certified radon measurement and mitigation professional lists.
View sourceClimate & Energy
Climate Zones
IECC Climate Zones in Iowa
6ACold
Zone 6A - Cold Humid
moist
4AMixed-Humid
Mixed-Humid
moist
5ACool-Humid
Zone 5A - Cool Humid
moist
Energy Code Requirements
IECC 2012 - Residential Insulation Minimums
| Component | Zone 6A | Zone 4A | Zone 5A |
|---|---|---|---|
Ceiling Attic | 49.0 | NR | 38.0 |
Wood Frame Wall | 20.0 | NR | 20.0 |
Mass Wall | 15.0 | NR | 13.0 |
Floor | 30.0 | NR | 30.0 |
Basement Wall | 15.0 | NR | 10.0 |
Slab Perimeter | 10.0 | NR | 10.0 |
Crawl Space Wall | 10.0 | NR | 10.0 |
Window | 0.300 | NR | 0.320 |
Skylight | 0.550 | NR | 0.550 |
Legend:
Ceiling Attic
Wood Frame Wall
Mass Wall
Floor
Basement Wall
Slab Perimeter
Crawl Space Wall
Window
Skylight
NR = Not Required
Fenestration Requirements
U-Factor (Max)
0.320
SHGC (Max)
0.40
Ice Barrier
Required
R-Value Requirements (Zone 6A - Most Common)
R-49.0
Ceiling
Attic/Roof
R-20.0
Walls
Wood Frame
R-30.0
Floor
Over Uncond.
R-15.0
Basement
Wall
R-10.0
Slab
Perimeter
NR
Crawlspace
Not Required
Counties
Iowa Counties
99 jurisdictions with code information
Adair County
FIPS: 19001
Standard
5 ZIP codesView
Adams County
FIPS: 19003
Standard
4 ZIP codesView
Allamakee County
FIPS: 19005
Standard
8 ZIP codesView
Appanoose County
FIPS: 19007
Standard
9 ZIP codesView
Audubon County
FIPS: 19009
Standard
6 ZIP codesView
Benton County
FIPS: 19011
Standard
16 ZIP codesView
Black Hawk County
FIPS: 19013
Standard
16 ZIP codesView
Boone County
FIPS: 19015
Standard
9 ZIP codesView
Bremer County
FIPS: 19017
Standard
8 ZIP codesView
Showing 9 of 99 jurisdictions.
Inspection Process
Inspection Process
Standard permit inspection sequence for Iowa residential projects
1
Footing Inspection
After excavation complete and reinforcement placed, before concrete pour. IOWA NOTE: Frost depth 36-48 inches depending on location. Verify footing depth meets local frost line requirements. Northern Iowa (Zone 6A) requires deeper footings (42-48"+). Verify excavation depth, width, and bearing surface. Reinforcing steel (if required) properly positioned and tied.
2
Foundation Inspection
Before backfilling and before superstructure construction. Anchor bolts/straps in place. Waterproofing and drainage systems (drain tile, damp-proofing) complete. Foundation walls properly cured. IOWA NOTE: Verify radon-resistant new construction (RRNC) sub-slab components if applicable - gas-permeable aggregate layer, vapor retarder, and sub-slab piping per IRC Appendix F. Iowa has highest radon levels in US.
If applicable
3
Rough Framing Inspection
After framing complete, roof sheathing installed, windows and exterior doors installed, before insulation. Verify structural connections, proper lumber grades, sheathing attachment, header sizes. Ice barrier installation verified (required statewide in Iowa, Zones 5A and 6A). IOWA NOTE: Due to tornado risk, verify enhanced roof-to-wall connections (hurricane clips/straps), proper sheathing nailing pattern, and gable end bracing per IRC R602.10.9.
4
Rough Mechanical/Electrical/Plumbing
After rough-in complete, before insulation. All electrical boxes installed, wiring run, service panel mounted. HVAC ductwork installed. Plumbing water supply and DWV systems complete. All penetrations and fire-stopping in place. IOWA NOTE: Radon vent pipe routing through building verified if RRNC installed. Ensure pipe is routed from sub-slab through conditioned space to above roof line.
Before drywall
5
Insulation/Energy Inspection
After insulation installed, before drywall. Verify R-values match approved plans and Iowa Energy Code requirements. IOWA ENERGY CODE (IECC 2012 statewide minimum): Zone 5A - R-38 ceiling, R-20 wall, R-30 floor, 7 ACH50. Zone 6A - R-49 ceiling, R-20+5ci wall, R-30 floor, 3 ACH50. Municipalities adopting IECC 2018 will have stricter requirements. Check air sealing at penetrations, gaps, and joints. Blower door test per local code. Vapor barriers properly installed where required.
Energy code compliance
Final Inspection
After all work complete and approved by all trades. All mechanical systems operational. Smoke detectors and CO detectors installed per IRC R314/R315. Handrails and guardrails in place. Site grading complete with positive drainage. All required documentation submitted. IOWA NOTE: Post-construction radon test recommended. Verify radon vent pipe extends above roof and is properly terminated. Energy code compliance documentation (REScheck or equivalent) complete.
CO Issued
Important Notes
24-Hour Notice: Schedule inspections at least 24 hours in advance.
Permit Card: Must be posted and visible from street.
Re-Inspection Fees
- First re-inspection
- Often free
- Second re-inspection
- $50-100
- Additional re-inspections
- Varies
* Fees vary by jurisdiction
Contacts & Resources
City of Des Moines Permit & Development Center
Des Moines
City of Cedar Rapids Building Services
Cedar Rapids
City of Davenport Development Services
Davenport
City of Sioux City Inspections Division
Sioux City
Iowa State Fire Marshal Division
State Building Code Authority
Iowa Utilities Board - Energy Code
Des Moines
Contractor Licensing
Contractor licensing in Iowa is managed at the state level. Contact the state licensing board or visit your local building department for specific requirements and license verification.
Data last verified: February 2026 · Always verify requirements with the local building department.