State building permit guide
Delaware building permits — complete guide (2026)
Delaware is the second smallest state with a simple, accessible permitting system. New Castle County (Wilmington) handles the bulk of permit volume. Sussex County on the shore sees significant vacation home construction activity.
Avg cost: $150–$600
Processing: 1–4 weeks
~6,500 permits/year
3 counties
$150–$600Average permit cost
1–4 weeksProcessing time
~6,500Permits issued/year
LimitedADU-friendly
Delaware has only 3 counties, making it one of the simpler permitting landscapes in the Northeast. New Castle County has a full permit system. Kent and Sussex Counties are more rural — check locally for requirements. Sussex County coastal areas may have additional flood zone requirements.
Permit costs by type — Delaware
| Permit type | Fee range | Processing time | Notes |
|---|---|---|---|
| Electrical | $75–$200 | 1–3 days | Licensed electrician required |
| Plumbing | $70–$185 | 1–3 days | Licensed plumber required |
| HVAC / Mechanical | $80–$220 | 1–4 days | Oil heat common — conversion permits common |
| Roofing | $100–$275 | 1–3 days | Full replacement permit required |
| New Construction | $600–$1,800 | 2–6 weeks | Sussex County coastal homes see premium costs |
| Room Addition | $350–$900 | 2–5 weeks | Straightforward process in most areas |
| Deck / Patio | $125–$375 | 1–3 weeks | Coastal setback rules may apply in Sussex |
| Pool | $175–$500 | 2–4 weeks | High demand in Sussex County |
| Solar | $80–$220 | 1–4 days | Good state net metering policy |
| Fence | $55–$150 | 1–5 days | Coastal setback requirements near dunes |
How to get a building permit in Delaware
1
Identify your county system
New Castle County has a robust online permitting portal. Kent County (Dover) and Sussex County (Georgetown) have their own separate systems.
2
Submit permit application
New Castle County accepts online submissions for most project types. Kent and Sussex are mostly paper-based.
3
Plans if required
Structural work requires stamped plans. Sussex County coastal projects may need flood elevation certificates.
4
Inspections
New Castle County has a dedicated inspection division. Sussex County may have longer waits during busy beach-home construction seasons.
5
Certificate of Occupancy
Required for new construction and major additions.
Permit costs by county — top Delaware counties
New Castle (Wilmington) County
$150–$600
2–5 weeks
Sussex (Rehoboth Beach area) County
$150–$550
2–5 weeks
Kent (Dover) County
$125–$425
1–4 weeks
Frequently asked questions — Delaware permits
Does Delaware require permits for beach house projects?
Yes. Sussex County coastal properties have additional requirements including FEMA flood zone compliance, coastal setback rules, and dune protection regulations.
What is the frost depth in Delaware?
Delaware's frost depth is 30–36 inches, shallower than New England but still requires compliant footings for all structural work.
Can I do my own plumbing in Delaware?
Homeowners can do their own plumbing on their primary residence in most Delaware jurisdictions, but a licensed plumber must perform the final connections in some counties.
Does Delaware have an ADU law?
Delaware does not have a statewide ADU law. Each municipality sets its own zoning rules for accessory dwelling units.
Data sources: US Census Bureau BPS 2024 · Delaware Delaware Office of State Fire Marshal / local building officials · Shovels.ai permit aggregator