AGrannio

Can You Build an ADU in Wilmington?

ADU rules in Wilmington are set by local zoning in Delaware. Many Delaware cities allow ADUs — here's what to check, plus typical costs ($154,000–$252,000 for a 700 sq ft detached unit).

Construction costs in Wilmington track close to the Delaware state average.

Detached ADU (700 sq ft)

$154,000–$252,000

Garage conversion (400 sq ft)

$48,000–$88,000

Statewide protection

Local rules

What applies in Wilmington

We do not yet publish a verified Wilmington ordinance summary. Use this page for a planning-level cost estimate, then check Wilmington's planning or building department for rules that apply to your parcel.

Estimate your Wilmington ADU cost

Your property

ADU type

Estimated cost in Delaware

$154,000 – $252,000

≈ $220–$360/sq ft turnkey · midpoint $203,000

$138,100
Construction
$36,500
Design & permits
$28,400
Site work
ADU rules in Delaware are set by your city — here's what to check.
  • iSize set locally. This state leaves ADU size limits to your city — typical caps run 600–1,200 sq ft. Check your local code.
  • iParking. Set by local ordinance — commonly 1 space per ADU unless near transit.
  • iOwner-occupancy varies. Owner-occupancy rules are set locally in this state.
  • ✓Lot has room. A 700 sq ft ADU uses about 12% of your 6,000 sq ft lot — comfortably within typical coverage limits.

Rule basis: Local zoning governs — rules vary by city/county

If you rent it out

$1,075–$1,750

est. rent/mo

8.4%

gross yield

12.8 yrs

payback

~$15,903/yr after a 7% vacancy allowance, before financing & maintenance.

Financed over 20 yrs at 7.5%, the build is about $1,635/mo — vs ~$1,425/mo in estimated rent.

Get your detailed feasibility report →

Estimates are for planning only and are based on regional construction-cost indices and published statewide ADU statutes. Local ordinances, lot conditions and contractor pricing vary — always confirm with your city planning department and a licensed contractor.

Get matched with a vetted ADU builder in Wilmington

Tell us about your project and we'll introduce you to a builder who works in your area. Free, no obligation.

Other Delaware cities

DoverNewark

Estimates are for planning only and are based on regional construction-cost indices and published statewide ADU statutes. Local ordinances, lot conditions and contractor pricing vary — always confirm with your city planning department and a licensed contractor.