Last updated: September 24, 2026
What affects the price
Building an ADU involves several moving parts that shape your total investment. The final figure depends heavily on whether you choose a prefab unit or a custom build from the ground up. Site conditions are another major factor; if your property requires extensive grading, utility trenching, or foundation work, costs will climb. You also have to consider your choice of finishes, like high-end appliances or custom cabinetry. Navigating local permit fees and impact assessments also adds to the total.
About this service
Building in San Diego requires specific expertise regarding coastal commission rules, fire safety standards, and local density bonuses. A contractor familiar with this area knows how to navigate the city’s unique permitting process to avoid common pitfalls. You need this service if you own property in San Diego and are ready to add a unit that complies with all regional housing ordinances and structural requirements.
Frequently asked in Washington
What are the disadvantages of ADUs in Washington D.C.?
How much does an ADU cost in Washington D.C.?
What are the rules for ADUs in Washington D.C.?
Can I build an ADU on my property in Washington D.C.?
How long does it take to build an ADU in Washington D.C.?
What permits do I need for an ADU in Washington D.C.?
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
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: Dupont Circle, Georgetown, Adams Morgan, Capitol Hill, U Street Corridor, Shaw — and every surrounding area.
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