State Guide · Verified 2026
Shed Installation Permits in Delaware
The Building Code in Delaware
No statewide code. New Castle and Sussex use 2021 IRC, Kent County uses 2018 IRC
Delaware's three counties, New Castle, Kent, and Sussex, each independently adopt and enforce their own residential code edition; there is no requirement that they match. New Castle County, revised as of January 1, 2026, exempts one-story detached residential accessory structures, including tool and storage sheds, playhouses, pergolas, and freestanding gazebos, under 200 square feet from a building permit. Sussex County takes the opposite approach: every accessory structure needs a county permit regardless of size, though the permitting track itself splits by size, a placement permit confirming setbacks below 400 square feet, and a full plan review with engineered drawings at or above that figure.
Quick Facts
Who Sets the Rules
Only 3 counties, 3 genuinely different rules
Delaware's small size, just three counties, doesn't translate into uniformity for sheds: New Castle exempts structures under 200 square feet, Kent uses its own separate cutoff, and Sussex requires a permit for an accessory building of any size at all, three real, independent local decisions.
Sussex County is the strictest county in the state for sheds specifically
Unlike New Castle and Kent, Sussex County has no square-footage exemption whatsoever: every home accessory building needs a county permit. The process itself still scales with size, a shed under 400 square feet only needs a simpler placement permit confirming setbacks, while 400 square feet or more triggers a full plan review with engineered construction drawings.
A pattern that reverses for a different project type
This is notably the opposite of how Sussex treats fences, where it's the most permissive of Delaware's three counties. The same county can be the strictest for one kind of structure and the most lenient for another, a real reminder that a county's general reputation doesn't predict every specific rule.
Wilmington adds its own layer on top of New Castle County
Wilmington runs its own building department in addition to the New Castle County rules that apply outside the city, meaning a shed within Wilmington city limits goes through city review rather than the county's process directly, with typical 3-foot rear and side setbacks.
Coastal flood requirements apply regardless of county
Construction in FEMA-mapped flood zones must meet elevation requirements for the lowest habitable floor, and this can extend to garages and large sheds, not just the house itself, a statewide concern that applies on top of whichever county's general shed rule governs the property.
What people get wrong
The most common mistake is assuming Delaware's three counties share a similar approach because the state itself is so small. Sussex County's no-exemption stance for sheds is a real, deliberate departure from New Castle and Kent, not a rounding error or a typo.
Counties With Their Own Rules
These Delaware counties have verified, county-specific shed installation rules that differ from the state baseline:
Check Your County
Select your county for the local rule, fees, and your building department's contact details:
Building It Yourself? Here's What You'll Need
Popular tools and materials homeowners use for a shed installation project:
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Official Sources
Rules change and cities within a county may differ. This guide is general information, not legal advice — always confirm with your local building department. Reviewed by the StateDataIndex Editorial Team · Updated September 2026.