A building permit in Wilmington is issued by the city’s Department of Land Use and Planning, which reviews plans, issues permits and carries out building inspections under the city’s own building code. The city’s own Fire Marshal’s Office handles fire plan review, and the Department of Licenses and Inspections handles code enforcement and rental inspections — so inside the city the process stays with the city, and New Castle County does not issue here.
Wilmington's distinctive requirement is a tested trade licence. Before the city will issue the business licence a permit depends on, a contractor in the mechanical trades — plumbing, heating, mechanical, refrigeration or electrical — must sit and pass a city trade test with the Chief Plumbing Inspector, a step that does not exist in the surrounding county.
This guide covers the city of Wilmington, in New Castle County. Work outside the city limits falls to the county or another municipality; confirm the address is inside the city before you file with the Department of Land Use and Planning.
The trade test comes before the licence, and the licence before the permit. For the mechanical trades, the city trade test with the Chief Plumbing Inspector is a precondition of the business licence, and the business licence is a precondition of the permit — so a contractor new to the city should clear the test well before the job needs to start.
What requires a building permit in Wilmington?
Delaware has no statewide building code. Each county, and each town that runs its own building department, adopts and enforces its own, and the editions, amendments and effective dates differ between them — so a rule that applies in one part of Delaware may simply not apply 30 minutes away. New Castle County administers its code through the Department of Land Use, Kent County through its Department of Planning Services (Division of Inspection and Enforcement), and Sussex County through its Building Permit Office and Building Code Office, which also cover a number of incorporated towns that have not taken the function on themselves. Above them sit statewide rules: plumbing, mechanical, fuel gas, energy and fire codes set at state level, electrical inspection by a state-licensed agency, and the State Fire Marshal's plan review. So in Wilmington the questions are which authority holds the building code, which edition it is on, and whether the contractor's trade is one the city tests before it will issue a business licence.
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Get a free quote →Typically permit required
- A City of Wilmington building permit from the Department of Land Use and Planning before construction, alteration or demolition
- The city fire marshal's plan review, carried out at City Hall rather than by the state office, on the work the fire code reaches
- A City of Wilmington business licence for the contractor, with the trade test passed first for the mechanical trades
- A Residential Property Rental Licence for any rental unit, renewed annually and inspected on the city's cycle
- Electrical work under state regulation, inspected by a licensed electrical inspection agency
- Stormwater approval from the delegated agency, and DNREC permits where the site triggers them
Often exempt
- City fire marshal plan review on buildings used wholly as dwellings of no more than two families
- City fire marshal plan review on buildings used wholly for farming purposes, rare within the city
- Ordinary repairs the adopted code places below the permit threshold
- Small accessory work where the code's own exemption reaches it
- Like-for-like finishes that do not alter structure, egress or building systems
Which authority holds the code for your address
Wilmington issues its own permits through its Department of Land Use and Planning and runs its own fire marshal, and for the mechanical trades it tests the contractor: a plumbing, heating, mechanical or electrical contractor must pass a city trade test with the Chief Plumbing Inspector before the city will issue the business licence that a permit depends on.
Delaware has no statewide building code — each county and town that runs a building department adopts its own — but plumbing, mechanical, fuel gas, energy and fire codes are set at state level, electrical work is inspected by state-licensed agencies, and the State Fire Marshal reviews plans for most non-residential work. Delaware rules
Who handles permitting in Wilmington?
The city of Wilmington is served by the Department of Land Use and Planning at the Louis L. Redding City/County Building, which reviews plans, issues building permits and carries out building inspections; 15 permitting and plan-review posts moved there from Licenses and Inspections in 2023. The Wilmington Fire Marshal’s Office, part of the Fire Department and in the same building, carries out the city’s fire plan review, and the Department of Licenses and Inspections handles code enforcement and rental inspections.
Not sure this scope needs a permit?
Get a free quote →| Detail | Information |
|---|---|
| Authority | City of Wilmington Department of Land Use and Planning |
| Office | Louis L. Redding City/County Building, 800 North French Street, Wilmington, DE 19801 |
| Code enforcement and rentals | Department of Licenses and Inspections, same building |
| Fire Marshal’s Office | Third floor; (302) 576-3120 or (302) 576-3122 |
| Applies where | Inside the city of Wilmington; New Castle County does not issue permits here |
In 2025, building permits issued in Wilmington authorized 101 new privately owned housing units, 17 of them single-family homes, according to the U.S. Census Bureau Building Permits Survey.
Permit types
Residential permits
Houses, additions, alterations and demolition inside the city are permitted through the Department of Land Use and Planning under the city's own adopted code. Rentals carry a separate obligation: every rental unit needs a Residential Property Rental Licence, renewed annually and inspected on a two- or five-year cycle, and an owner who lives outside New Castle County must retain a city-licensed property manager.
Commercial permits
Commercial and multi-family projects are reviewed under the city's adopted construction codes, and the city fire marshal — not the state office — carries out the fire plan review at City Hall, with a surcharge where work proceeds without the review it requires. For the trades on the job, the city's tested business licence still governs who may pull the trade permits.
The state reviews that run alongside the permit
In Wilmington the city operates its own fire marshal, so the plan review that the state office performs elsewhere is carried out at City Hall.
Delaware has no general contractor licence: contractors need a state contractor business licence and Department of Labor registration, and electricians, plumbers, HVACR and fire protection contractors are licensed by the state. Delaware rules
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Call 1-855-478-4290 →Wilmington permit costs and fees
Wilmington sets its permit, inspection and licence fees in the city code, and scales the permit to the work. Two figures are worth knowing up front: the commercial certificate fee and the annual mechanical-trade licence that only issues once the trade test is passed.
| Item | Fee or rule |
|---|---|
| Building permit | Set under the city code and scaled to the work; a plan review fee applies |
| Commercial certificate | $300 for a commercial property or use under the current schedule |
| Mechanical trade licence | An annual city business licence — $200 for an electrical contractor — issued only after the trade test is passed |
| Plan review | A surcharge applies where work proceeds without the city fire marshal's required plan review |
A rental is a recurring licence, not a one-time permit. Every rental unit in the city carries an annual Residential Property Rental Licence and a periodic inspection, and an out-of-county owner must keep a city-licensed property manager on retainer — ongoing costs that sit outside the one-time building permit.
Trade permits and who may pull them
Permit required
- Electrical — by a licensed electrician, inspected by a licensed electrical inspection agency
- Plumbing — by a plumber licensed through the state Plumbing and HVACR board
- Fire protection — by a contractor licensed by the State Fire Marshal, whose licence number goes on the plan review
- Mechanical and fuel gas — under the statewide codes adopted by the state Plumbing and HVACR board, enforced by the county or town
Typically exempt
- Work the adopted code edition places below the permit threshold, which differs between the three counties
- Like-for-like replacement not amounting to a new installation
Rather not deal with the building department?
Get a free quote →Electricians, plumbers and fire protection contractors hold state licences, and electrical inspection is carried out by licensed inspection agencies. Delaware rules
How to apply for a Wilmington building permit
County in unincorporated areas, the municipality where it runs a building department, and in some towns the county for building with the town for zoning.
The three counties are on different editions with different effective dates and amendments.
Required on new buildings, additions, changes of occupancy and fire damage, except two-family dwellings and farm buildings, and on sprinkler, alarm and fuel installations and tenant fit-outs.
Sediment and stormwater approval from the delegated agency (conservation district, county or city), and DNREC wetlands or beach approvals where the site needs them.
Many permit offices ask for the Delaware contractor business licence, contractors must be registered with the Department of Labor, and some municipalities require their own licence.
Footing to final with the authority, electrical through a licensed inspection agency, then the certificate of occupancy.
Review, corrections and what actually causes delay
The Wilmington delays that recur are licensing delays, not drawing delays: a mechanical-trade contractor who has not yet passed the city trade test, a business licence not yet issued, or a rental brought into service without its licence and inspection. Clearing the trade test and the business licence before the permit application, and settling the rental licence separately, keeps the permit review on track.
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Get a free quote →Inspections in Wilmington
Inspections follow the sequence in whichever code edition the authority has adopted — footing, foundation, framing, rough trades, insulation and final — requested from the county or the municipality against the permit number. Electrical inspections are the exception: they are carried out by licensed electrical inspection agencies, and their approval documentation is what the permitting authority and the State Fire Marshal rely on. A certificate of occupancy closes the file, and where the fire marshal reviewed the plans its own approval is a precondition of that certificate. In Wilmington the building inspections run through the Department of Land Use and Planning against the permit number, the city fire marshal's approval is a precondition where the plan review applied, and a certificate closes the file.
Wilmington permit search and official resources
- City of Wilmington Department of Licenses and Inspections — code enforcement and rental inspections; building permits now come from the Department of Land Use and Planning
- Wilmington business licence and permit lookup — searching business licences, fire permits and inspection accounts
- Delaware State Fire Marshal, building plan submittals — what needs plan review, the fee formula and what must accompany a submission
- Delaware Code title 16, chapter 66 — the statutory plan review requirement and its exceptions
- Delaware Department of Natural Resources and Environmental Control — wetlands, subaqueous-lands and beach approvals, and the sediment and stormwater programme
Frequently asked questions
Does the city or New Castle County issue my permit?
Inside the city of Wilmington, the Department of Land Use and Planning issues the permit and New Castle County does not. The city runs its own building code, fire marshal and licensing, so the whole process stays with the city.
Inspections are where schedules slip.
Get a free quote →Do contractors need to pass a test?
For the mechanical trades, yes. A plumbing, heating, mechanical or electrical contractor must pass a city trade test with the Chief Plumbing Inspector before the city will issue the business licence that a permit depends on.
Do I need a rental licence?
Every rental unit in the city must hold a Residential Property Rental Licence, renewed annually and inspected on a two- or five-year cycle depending on the number of units. An owner who lives outside New Castle County must retain a city-licensed property manager.
Who reviews my plans for fire?
Wilmington operates its own fire marshal, so the plan review that the state office carries out elsewhere is done at City Hall. A surcharge applies where work proceeds without the required plan review.
Which code applies in the city?
The city enforces its own adopted construction codes through the Department of Land Use and Planning, separate from the county’s editions. Confirm the current edition and any city amendment with the department before you design to it.
How do I check a licence or permit?
The city's online self-service lets you search business licences, fire permits and inspection accounts by address or account number. It is the quickest way to confirm a contractor's city licence before work begins.
Simplify Wilmington permitting with Alliance Permitting
21+ years of working real jurisdictions is what tells you that Wilmington is its own world inside the county: a tested trade licence, a city fire marshal doing the plan review the state does elsewhere, and a rental licence program with its own inspection cycle. Our team gets the trade test and business licence sorted before the permit goes in, confirms the review path with the Department of Land Use and Planning and the Fire Marshal’s Office, files the submittal, and tracks it through to a certificate — corrections included.
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Send us the scope and the parcel. We confirm the review path with the City of Wilmington Department of Land Use and Planning, assemble the submittal, file it, and track it through issuance — corrections included.
More Delaware permitting guides
More Delaware permitting guides
This guide is provided by Alliance Permitting for general information about Wilmington permitting. Requirements, fees, and procedures change; confirm details with the permitting authority before relying on them.