ADU Laws in District of Columbia (2026)
District of Columbia state ADU law details, key provisions, preemption status, and recent legislative changes for accessory dwelling units.
Law Name
DC Zoning Regulations Title 11 DCMR — Accessory Dwelling Unit Provisions
Effective Date
2016-09-06
Preempts Local Ordinances
No — local rules may be stricter
Has State Law
Yes
Key Provisions
Washington DC is its own complete jurisdiction under the Home Rule Charter — there is no state to preempt DC; DC Council controls all local zoning through 11 DCMR
DC allows ADUs by right in residential zones under 11 DCMR 1000 series provisions
No owner-occupancy requirement — owners may rent both primary unit and ADU simultaneously
No minimum parking required for ADUs — DC's transit access eliminates this requirement
ADU permitting processed through DC Department of Buildings via DC Access online portal
Historic preservation review required for properties in DC historic districts (approximately 30% of DC residential properties)
DC does not impose development impact fees, reducing ADU cost compared to many cities
Maximum one ADU per single-family lot in R-1 through R-4 zones
Detached ADU maximum 1,000 sqft or 35% of primary unit floor area
DC Zoning Commission periodically updates ADU provisions through formal rulemaking under Home Rule authority
Legislative History
2016 — 11 DCMR Amendment — ADU Provisions
DC Zoning Commission adopted comprehensive ADU provisions under 11 DCMR 1000 series effective September 6, 2016. Established by-right ADU approval, setback standards (12 ft rear, 3 ft side), maximum size (1,000 sqft or 35% of primary unit floor area), and no-parking policy. DC operated under Home Rule authority — these are local DC regulations, not state preemption.
2022 — 11 DCMR Amendment — ADU Expansion
DC Zoning Commission expanded ADU provisions to streamline the approval process and align with DC's affordable housing goals. Updates to setback standards, maximum size allowances, and processing timelines. DC DHCD housing programs provide supplemental incentives for income-restricted ADU production.
Official Sources
Source: DC Zoning Regulations Title 11 DCMR — Accessory Dwelling Unit Provisions. Last verified April 6, 2026. View source