Delaware Plumbing Inspection: Process, Fees, and Re-Inspection Rules

Inspections Are Managed Locally, Not by the State Licensing Board

The Division of Professional Regulation issues your Master Plumber license, but they don't inspect your work. Plumbing inspections in Delaware are handled by whichever local Authority Having Jurisdiction covers the job site — the Division of Public Health in unincorporated Kent and Sussex County areas, New Castle County's Department of Land Use, or the municipal inspection departments in Wilmington, Dover, and Newark.

Each authority runs its own scheduling system and charges its own fees. Code editions differ: the Division of Public Health and New Castle County list the 2021 International Plumbing Code (IPC) with Delaware amendments, while Wilmington and Newark list the 2018 IPC. Getting the process wrong doesn't just delay the project — it can trigger re-inspection fees that eat into your margins.

The Standard Inspection Sequence

Regardless of which jurisdiction manages the inspection, plumbing projects in Delaware generally follow a three-phase sequence:

Rough-in inspection. Conducted after the drain, waste, and vent piping is installed but before walls and ceilings are closed up. The inspector verifies pipe sizing, slope, material compatibility, and code-required clearances. All piping must be pressurized and accessible — if the inspector arrives and finds drywall covering the rough-in, you'll be asked to demo it and reschedule.

Top-out inspection. Covers the water supply distribution system after piping is complete but before fixtures are set. The inspector checks pressure testing, support and securing, and proper valve placement.

Final inspection. Conducted after all fixtures are installed, connected, and operational. The inspector runs water through the system, checks trap seals, verifies temperature-pressure relief valve configurations on water heaters, and confirms that the installation matches the approved permit drawings.

DPH Inspection Rules (Kent and Sussex Counties)

The Division of Public Health manages inspections in areas without local code enforcement departments. Their rules are straightforward:

• Schedule inspections at least three business days in advance
• The first three inspections per permit are included in the $100 permit fee
• Each additional inspection beyond the third costs $50
• The inspector will verify compliance with the 2021 IPC plus Delaware-specific amendments

The three-inspection limit is the most important number to remember. If your rough-in, top-out, and final all pass on the first visit, you pay nothing beyond the original permit fee. But if a rough-in fails and needs a re-inspection, that's your third included visit used up — and the final inspection becomes a $50 charge.

New Castle County Inspections

New Castle County schedules inspections through its Inspection Scheduling and Permit Details portal at https://inspections.newcastlede.gov. Permit applications and plan review go through eServices/ePlans, where applicants can view project status and review progress.

The county enforces the same 2021 IPC with Delaware amendments, but local NCC-specific amendments may apply for projects in the unincorporated county area. Contractors must hold an active NCC business registration before the county will accept inspection requests.

Wilmington Inspections

The City of Wilmington's Department of Licenses and Inspections enforces building subcode compliance alongside the adopted plumbing code. Wilmington runs its own inspection scheduling — separate from NCC — and applies its own fee structure.

The city lists a $20 fee per trade and $12 per $1,000 of construction costs. The Certificate of Compliance fee is $50.

Dover Re-Inspection Fees

Dover uses an escalating re-inspection fee schedule that makes failed inspections progressively more expensive:

• First re-inspection: free
• Second re-inspection: $25
• Third re-inspection: $50
• Subsequent re-inspections: $100 each

This structure penalizes repeat failures more heavily than a flat re-inspection fee would. A plumber who fails the rough-in twice and then has a final inspection issue could pay $75 in re-inspection fees on top of the original permit cost.

How to Avoid Re-Inspection Charges

Most failed inspections come down to a few preventable issues:

Incomplete work. Calling for an inspection before all required work in that phase is actually finished. If the inspector arrives for a rough-in and finds supply lines not yet pressurized, it counts as a failed inspection even though nothing is technically wrong.

Accessibility. Piping must be visible and accessible at the time of inspection. Covered pipe, cluttered work areas, or locked job sites all result in a failed visit.

Permit mismatch. The installation must match what was submitted on the permit application. Significant changes in fixture count, pipe routing, or equipment specifications need a permit revision before the inspection, not an explanation during it.

Code reference. The applicable edition depends on the AHJ: the Division of Public Health and New Castle County list the 2021 IPC with Delaware amendments, while Wilmington and Newark list the 2018 IPC. Confirm the applicable code and amendments with the permitting office for the job site.

The Delaware Plumber License Guide includes a jurisdiction-by-jurisdiction inspection directory covering scheduling methods, fee schedules, and the specific portal links for each AHJ in the state.

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