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Delaware Counties
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Overview
Delaware adopted 2018 I-Codes statewide. Climate Zone 4A. 3 counties (New Castle, Kent, Sussex). Coastal flood zones along Delaware Bay and Atlantic.
Code Snapshot
Current editions in effect
Building Code
IBC Not Adopted Statewide
Not Adopted Statewide
Building Code
IEBC Not Adopted Statewide
Not Adopted Statewide
Energy
IECC 2018
2018 Edition
Energy
IECC-C Not Adopted Statewide
Not Adopted Statewide
Residential
IECC-R Not Adopted Statewide
Not Adopted Statewide
Fire Code
IFC 2021
2021 Edition
Effective Date: January 1, 2024
Verified: Mar 2026
Jurisdiction Complexity
Delaware is a MODERATE complexity state
Delaware 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 Delaware restoration work
The Delaware Office of the State Fire Marshal administers and enforces all building codes statewide. Unlike many states where local jurisdictions adopt codes independently, Delaware has uniform statewide code adoption through the State Fire Marshal.
Important: Delaware Code Title 16, Chapter 66 grants the Office of the State Fire Marshal (OSFM) authority over building and fire code adoption and enforcement statewide. The OSFM adopts the International Code Council (ICC) codes with Delaware-specific amendments. The 2018 I-Codes are the currently adopted edition. The OSFM operates regional offices that perform plan review, issue permits, and conduct inspections. Some municipalities (Wilmington, Dover, Newark) have delegated authority to operate their own building departments, but they must enforce the state-adopted codes. The OSFM Fire Prevention Commission is the rule-making body that formally adopts code editions and amendments.
Delaware adopted the 2018 IRC statewide with Delaware-specific amendments. Code is enforced through the Delaware State Fire Prevention Commission for unincorporated areas and by local governments in incorporated areas.
Important: Delaware adopted a mandatory statewide building code based on the 2018 IRC with Delaware-specific amendments. The State Fire Prevention Commission enforces codes in unincorporated areas of Kent and Sussex counties. Incorporated municipalities (Wilmington, Dover, Newark, etc.) enforce their own building codes but must meet the minimum state standard. New Castle County has its own Department of Land Use that handles permitting. Delaware is a small state but code enforcement structure varies between the three counties and incorporated municipalities. All residential construction must comply with the state minimum code.
Delaware enforces building codes statewide. Permits are generally required for roof replacement.
Important: IRC Section R105 establishes when building permits are required. Roof replacement (re-roofing) generally requires a building permit in jurisdictions that enforce the IRC or an equivalent building code. Delaware adopts codes statewide, so virtually all jurisdictions require roof permits. Permit applications typically require contractor license verification, material specifications, and project scope description. Inspections include sheathing (if exposed) and final. IRC R105.2 exempts ordinary maintenance (minor repairs, re-attachment of trim), but full roof replacement is NOT exempt from permit requirements.
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Code Administration
Administering Agency
Delaware Building Commission
Code Portal
stateplanning.delaware.govState Statute
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Jurisdictions
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ZIP Codes
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Special Zones
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Codes
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Climate Zones
Applicable Codes
Key Codes for Restoration Work
Primary codes for residential restoration projects in Delaware
| Code Type | Current Edition | Effective Date | Base Code | Status | Actions |
|---|---|---|---|---|---|
International Building Code Commercial & Multi-Family | IBC Not Adopted Statewide | Jan 1, 2024 | IBC 2021 w/ amendments | Current | View Details |
International Existing Building Code Commercial & Multi-Family | IEBC Not Adopted Statewide | Jan 1, 2024 | IBC 2021 w/ amendments | Current | View Details |
International Energy Conservation Code 2018 Energy Efficiency Standards | IECC 2018 | Mar 1, 2019 | IECC 2018 w/ amendments | Current | View Details |
International Energy Conservation Code (Commercial) Energy Efficiency Standards | IECC-C Not Adopted Statewide | Jan 1, 2024 | IECC 2021 w/ amendments | Current | View Details |
International Energy Conservation Code (Residential) Single-Family & Townhomes | IECC-R Not Adopted Statewide | Jan 1, 2024 | IRC 2021 w/ amendments | Current | View Details |
International Residential Code 2018 Single-Family & Townhomes | IRC 2018 | Jan 1, 2019 | IRC 2018 w/ amendments | Current | View Details |
National Electrical Code 2020 (NFPA 70) Building Requirements | NEC 2020 | Sep 1, 2020 | NEC 2018 w/ amendments | Current | View Details |
International Building Code
Commercial & Multi-Family
IBC Not Adopted StatewideDetails
International Existing Building Code
Commercial & Multi-Family
IEBC Not Adopted StatewideDetails
International Energy Conservation Code 2018
Energy Efficiency Standards
IECC 2018Details
International Energy Conservation Code (Commercial)
Energy Efficiency Standards
IECC-C Not Adopted StatewideDetails
International Energy Conservation Code (Residential)
Single-Family & Townhomes
IECC-R Not Adopted StatewideDetails
International Residential Code 2018
Single-Family & Townhomes
IRC 2018Details
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).
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Enter a Delaware ZIP code for exact applicable codes, special zones, and a compliance checklist.
Special Zones
Special Zones
Radon
Delaware EPA Radon Zone 2 — New Castle County
New Castle County falls within EPA Radon Zone 2 with predicted indoor screening levels of 2-4 pCi/L. The Piedmont geology in northern Delaware with fractured rock produces moderate radon risk. IRC R324 radon-resistant new construction is recommended for new homes in New Castle County. Kent and Sussex counties are Zone 3 (lower risk) but testing is still recommended.
Flood & Coastal
Delaware Riverine and Tidal Flood Zones AE
Delaware has extensive Zone AE designations along the Delaware River, Christina River, Brandywine Creek, and tidal marshes. Sussex County coastal communities have both riverine and coastal Zone AE. Delaware requires 18 inches of freeboard above BFE for new residential construction statewide per Title 7 Delaware Code. NFIP requirements per 44 CFR 60.3 apply with state-enhanced standards.
Seismic
Delaware Seismic Design Category A-B
Delaware falls within Seismic Design Categories A and B per ASCE 7-22. The state is near the Fall Line seismic zone. While moderate risk, all structures must meet minimum seismic detailing requirements per IBC Chapter 16. New Castle County has slightly higher spectral acceleration values than downstate counties.
Historic Preservation
Historic Districts (New Castle, Dover Green, Wilmington)
Delaware has several significant historic districts listed on the National Register of Historic Places. Key districts include: (1) New Castle Historic District - one of the oldest continually inhabited towns in North America, extensive Colonial, Federal, and Victorian architecture. (2) Dover Green Historic District - centered on the colonial-era town green where the US Constitution was ratified. (3) Multiple Wilmington historic districts including the Quaker Hill Historic District, Ninth Ward, and Forty Acres. (4) Lewes Historic District - first European settlement in Delaware (1631). Additional districts throughout the state.
Requirements: Work within designated historic districts may require review and approval by local historic preservation commissions or the Delaware State Historic Preservation Office (SHPO). Exterior modifications must be compatible with historic character. Replacement materials should match original in type, design, color, and texture. Window replacement in historic districts often requires matching original profiles or retaining historic windows with storm windows. Tax incentives available through Federal Historic Preservation Tax Incentives program and Delaware Historic Preservation Tax Credit. Secretary of Interior Standards for Rehabilitation apply for tax credit projects.
View sourceWind & Hurricane
Wind-Borne Debris Region (Coastal Delaware)
Coastal portions of Sussex County where ultimate design wind speeds are 130 mph or greater, or areas within 1 mile of the coastal mean high water line where wind speeds are 110 mph or greater. Per IRC R301.2.1.2. Primarily affects the Atlantic coast beach communities and areas immediately inland. Some portions of the Delaware Bay coastline may also be affected.
Requirements: Glazed openings (windows, sliding glass doors, skylights) must be protected with impact-resistant glazing or an approved impact-resistant covering system (shutters). Protection must resist impact of wind-borne missiles per ASTM E1996 and ASTM E1886. Garage doors must comply with ANSI/DASMA 108 for wind-borne debris impact. Entry doors must be impact-rated or protected. Enhanced roof sheathing attachment: 8d ring-shank nails at 4" OC at panel edges and 6" OC at intermediate supports. Enhanced roof covering attachment required per manufacturer high-wind installation instructions. Six nails minimum per asphalt shingle strip.
View sourceClimate & Energy
Climate Zones
IECC Climate Zones in Delaware
4AMixed-Humid
Mixed-Humid
moist
Energy Code Requirements
IECC 2018 - Residential Insulation Minimums
| Component | Zone 4A |
|---|---|
Wood Frame Wall | 20.0 |
Mass Wall | 8.0 |
Floor | 19.0 |
Basement Wall | 10.0 |
Slab Perimeter | 10.0 |
Crawl Space Wall | 10.0 |
Window | 0.350 |
Skylight | 0.550 |
Door | 0.350 |
Ceiling Attic | 49.0 |
Legend:
Wood Frame Wall
Mass Wall
Floor
Basement Wall
Slab Perimeter
Crawl Space Wall
Window
Skylight
Door
Ceiling Attic
NR = Not Required
Fenestration Requirements
U-Factor (Max)
0.350
SHGC (Max)
0.40
Ice Barrier
Required
R-Value Requirements (Zone 4A - Most Common)
R-49.0
Ceiling
Attic/Roof
R-20.0
Walls
Wood Frame
R-19.0
Floor
Over Uncond.
R-10.0
Basement
Wall
R-10.0
Slab
Perimeter
NR
Crawlspace
Not Required
Counties
Inspection Process
Inspection Process
Standard permit inspection sequence for Delaware residential projects
1
Footing Inspection
After excavation complete and reinforcement placed, before concrete pour. Verify excavation depth, width, and bearing surface. Reinforcing steel (if required) properly positioned and tied. Forms clean and properly braced. In flood zones, verify elevation relative to BFE.
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. In FEMA flood zones, verify flood openings in Zone A or elevated foundation in V-zones. Coastal Sussex County: verify piling embedment depth and connection details.
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, Zone 4A). In high-wind coastal areas: verify hurricane strap/clip connections, enhanced sheathing nailing schedule, and impact-rated glazing or shutter provisions.
4
Rough Mechanical/Electrical/Plumbing
After rough-in complete, before insulation. All electrical boxes installed, wiring run, service panel mounted. HVAC ductwork installed and sealed. Plumbing water supply and DWV systems complete. All penetrations and fire-stopping in place. Duct leakage testing may be required per IECC 2018.
Before drywall
5
Insulation/Energy Inspection
After insulation installed, before drywall. Verify R-values match approved plans (Zone 4A: R-49 ceiling, R-20 wall, R-19 floor). Check air sealing at penetrations, gaps, and joints. Blower door test to verify <=3 ACH50 air leakage. Vapor barriers properly installed. All duct sealing complete.
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 away from foundation. All required documentation submitted including elevation certificate (flood zones), energy compliance documentation, and truss/engineering documents. Address numbers posted and visible from street.
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
Sussex County Building Code Department
Georgetown
New Castle County Department of Land Use
New Castle
Kent County Levy Court - Inspections & Enforcement
Dover
Sussex County Building Code Department
Georgetown
Delaware Office of the State Fire Marshal
State Building Code Authority
Contractor Licensing
Contractor licensing in Delaware 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.