Cost to build accessory dwelling unit

Looking for cost to build accessory dwelling unit in Washington, DC? Call AccessoryDwellingUnit Pros for a contact a provider — no obligation. Licensed adu builders serve Washington and the surrounding area, and you'll get straight answers on timing and what affects the price.

Last updated: September 24, 2026

What affects the price

Building an ADU is a custom project, so costs vary based on your specific choices. Site conditions are the biggest factor; if your land requires significant grading, utility extensions, or foundation work, those expenses add up quickly. Choosing high-end finishes, custom cabinetry, or complex roof lines will also push the budget higher compared to a standard design. Prefabricated units often offer predictable costs, while custom site-built structures allow for more flexibility but can be harder to estimate upfront. Exact pricing confirmed free on the call.

About this service

Determining the cost requires looking at site preparation, foundation work, and the level of interior finishing you choose. Costs change based on whether you opt for a pre-designed layout or custom architecture. You should research these costs when you are ready to evaluate the financial return of your property upgrade. Exact pricing confirmed free on the call.

Frequently asked in Washington

What are the disadvantages of ADUs in D.C.?

How much does an ADU cost in D.C.?

What are the rules for ADUs in D.C.?

Is an ADU allowed in Washington D.C.?

Yes, ADUs are permitted in many residential zones across Washington D.C., provided they comply with the district's zoning and building codes. Eligibility is often determined by your property's zoning and lot characteristics. A quick call can verify your property's suitability.

What is the grant for ADUs in D.C.?

What permits are needed for an ADU in D.C.?

You will require building permits from the D.C. Department of Consumer and Regulatory Affairs (DCRA). This ensures your ADU meets all safety and code standards. The experienced contractors we work with manage this entire permit process for you.

Also serving nearby: Alexandria · Baltimore · Richmond · Reading · Philadelphia

All cities in District of Columbia →

More on this: HUD ADU resources — ADU policy and financing research.

Service area details

678,972residents

11,107per sq mile

8ZIP codes served

Serving all of Washington — population 678,972; about 11,107 residents per square mile across 61.1 sq mi. ZIP codes covered include 20001, 20002, 20003, 20004, 20005, 20006, 20007, 20008.

Neighborhoods served in Washington: Georgetown, Capitol Hill, Dupont Circle, Adams Morgan, Columbia Heights, U Street Corridor — and every surrounding area.