Can I Build an ADU in Washington?
Data version: Q2 2026 · Last updated 2026-05-13
Buildability City Score™: B (Middle 48%) · Median permit time: 88 days
TL;DR. Washington is one of the ADU-friendlier cities in District of Columbia. Buildability™ checks the Washington ADU ordinance, District of Columbia state law, your zoning district, lot size, setbacks, parking, and owner-occupancy rules in about 20 seconds — free for your first check.
Washington ADU rules at a glance
DC legalized accessory apartments and ADUs in 2016 and expanded rules in 2022. ADUs up to 900 sqft allowed by right on qualifying lots. Basement conversions are the most common ADU type due to rowhouse density. No parking required for ADUs.
Typical Washington lot profile
Most Washington single-family parcels are about 1,800–3,500 sqft with a median home price near $650,000 in a city of roughly 690K residents. Lot size drives ADU feasibility — smaller lots often still qualify for a JADU even when a detached ADU doesn't fit.
ADU vs JADU
A detached ADU is a new stand-alone structure. An attached ADU is built onto the primary home. A JADU (Junior ADU) is carved out of the existing house with a small kitchenette — usually capped around 500 sqft but easier to permit. Buildability™ checks eligibility for all three types on your specific Washington address.
Next steps
Enter your Washington address into Buildability™ for a free ADU eligibility check. If your lot qualifies, hire a licensed architect and a permit expediter who knows the Washington planning and building departments.
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