New Castle County, DE Fence Regulations: Retaining Walls (2026)
Key Facts
- No-review threshold
- 4 feet exposed height
- Above 4 feet
- Engineered to IBC §1807.2
- Governing chapter
- Chapter 12, Drainage
- Max daily fine
- $1,000 per violation-day
- Coverage
- Unincorporated County only
Summary
New Castle County lets you build a retaining wall up to four feet exposed height without engineering review. Cross that line and the Department of Land Use requires an International Building Code-compliant design and approval before you touch dirt.
E.Retaining walls. Retaining walls in excess of four (4) feet exposed height shall be located as far as necessary from the property line to accommodate the maintenance or replacement of structural components. Retaining walls more than four (4) feet exposed height shall be designed according to the International Building Code §1807.2, conform with the latest version of the Department's checklist and be approved by the Department.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 5).
Full Breakdown
Under Sec. 12.03.003(E) of the County Code, a residential retaining wall over four feet of exposed height must be engineered to International Building Code §1807.2, follow the Department's current checklist, and get Department approval, and it must sit far enough off the property line to allow future maintenance or replacement. Walls at or under four feet skip that engineering track and, per Sec. 6.03.012.C.1.h, don't even need a building permit unless they hold back a surcharge load or impound liquids. This is unincorporated-county law; Wilmington and Newark run their own building codes.
Violations & Fines
Building an unpermitted or non-compliant wall over four feet risks a stop-work order, an administrative fine up to $1,000 per day under Sec. 6.12.002, and the Code Official withholding future permits until you fix it.
Frequently Asked Questions
Do I need a permit for a short retaining wall in New Castle County?
What happens once a wall passes four feet?
Does this rule cover Wilmington or Newark?
Sources & Official References
Other rules in New Castle County
Compare New Castle County to another location·View the Delaware fence regulations overview
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