New Castle County, DE Building Safety: Building Permits (2026)
Key Facts
- Exempt patio/hardscape height
- 30 in. or less above grade
- Exempt detached deck size
- 200 sq ft or less
- Exempt detached deck height
- 30 in. or less above grade
- Attached decks
- always need a permit
- Residential deck permit window
- start 30 days, finish 90 days
Summary
A building permit is required for most decks and patios, but small unattached decks and low hardscape patios are exempt if they stay under set size and height limits.
i. Non-structural concrete slabs, patio and decorative hardscaping not more than thirty (30) inches above grade at any point... b. Decks not exceeding two hundred (200) square feet in area, that are not more than thirty (30) inches (762 mm) above grade at any point and are not adjacent to, or attached to, a one- or two-family dwelling.
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
New Castle County's Building Code (Chapter 6) exempts two specific structures from a permit: non-structural concrete slabs, patios, and decorative hardscaping that stay 30 inches or less above grade at any point, and detached decks (not attached or adjacent to a one- or two-family dwelling) that are 200 square feet or smaller and no more than 30 inches above grade. Any deck attached to the house, or any deck/patio exceeding those size or height thresholds, needs a building permit from the Department of Land Use's Code Official before construction. Where a permit is required, residential deck permits must start work within 30 days and finish within 90 days of issuance. This chapter applies to unincorporated New Castle County and to any incorporated municipality whose governing body has separately elected to adopt it (listed in the Chapter's Appendix 6); Wilmington and Newark run their own building departments and permit rules under their own municipal codes, not this one.
Violations & Fines
Building without a required permit exposes the owner to administrative penalties and fees set by the Code Official, on top of the permit fee once obtained; work started before permit issuance triggers those penalties automatically under Sec. 6.03.016(D).
Frequently Asked Questions
Do I need a permit for a small patio in New Castle County?
Can I build a deck without a permit?
Sources & Official References
Other rules in New Castle County
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