ADU Regulations in Delaware (DE)
Delaware is rated Moderate for ADU construction with an ADU-friendliness score of 30/100 (Restrictive). Delaware does not have a statewide ADU law — regulations are set entirely by local jurisdictions. Owner must reside on the property. Additional parking may be required. Delaware has no statewide ADU law. Sussex County and New Castle County have provisions for ADUs in certain zones. The state legislature has considered but not passed ADU reform bills. Wilmington allows ADUs in some residential zones.
Full ADU Regulations Summary for Delaware
| ADUs Allowed | Yes |
| Statewide ADU Law | No |
| Maximum ADU Size | Set locally |
| Owner Occupancy Required | Yes |
| Parking Required | Yes |
| Minimum Setback | Set locally |
| Permitting Timeline | Varies by jurisdiction |
| Impact Fees | Varies by jurisdiction |
| Long-Term Rental Allowed | Yes |
| Short-Term Rental (Airbnb) Allowed | Yes |
| Ease of Building | Moderate |
ADU Regulations by City in Delaware
ADU rules can vary by city even within the same state. Without a statewide ADU law, Delaware cities set their own rules, and policies can differ significantly. Below are ADU details for 2 cities in Delaware.
Wilmington
ADUs allowed in certain residential zones with conditional use approval. Owner occupancy typically required.
Dover
Limited ADU provisions. Requires conditional use permit in select zones.
How Delaware Compares to Other States
Below is a comparison of Delaware with five states that have similar ADU-friendliness scores. This comparison helps illustrate where Delaware stands nationally.
| State | Score | Statewide Law | Parking Req? | Owner Occ? | Ease |
|---|---|---|---|---|---|
| Delaware (DE) | 30 | No | Yes | Yes | Moderate |
| Alabama (AL) | 30 | No | Yes | Yes | Difficult |
| Georgia (GA) | 30 | No | Yes | Yes | Moderate |
| Idaho (ID) | 30 | No | Yes | Yes | Moderate |
| Illinois (IL) | 30 | No | Yes | Yes | Moderate |
| Indiana (IN) | 30 | No | Yes | Yes | Difficult |
Frequently Asked Questions About ADUs in Delaware
Can I build an ADU in Delaware?
Yes, ADUs are allowed in Delaware. However, Delaware does not have a statewide ADU law, so the specific rules depend on your city or county's zoning code. Some cities are more permissive than others. The ease of building is rated "Moderate" with a friendliness score of 30/100.
Do I need to live on the property to have an ADU in Delaware?
Yes, Delaware generally requires owner occupancy — the property owner must live either in the main house or the ADU. This means you cannot rent out both units simultaneously. Note: individual cities may have their own owner-occupancy rules, so check your local zoning.
How big can an ADU be in Delaware?
Delaware does not set a statewide maximum ADU size — this is determined by your local jurisdiction. Common local limits range from 600 to 1,200 square feet. Check your city's zoning code for the specific maximum.
How long does it take to get an ADU permit in Delaware?
The permitting timeline in Delaware is: Varies by jurisdiction. Without a statewide mandate, permitting timelines depend entirely on your local jurisdiction's review process.
Who decides ADU rules in Delaware?
Your city or county — Delaware has no statewide ADU statute, so zoning boards set the rules jurisdiction by jurisdiction. We track 2 Delaware cities above (including Wilmington); if yours isn't listed, the planning or zoning office is the authoritative source.
Check ADU Rules for Your City
Use our ADU regulations lookup tool to find the specific rules for your city in Delaware, or browse all 50 states to compare ADU regulations across the country.