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
Effective Date
2016-09-06
Preempts Local Ordinances
No — local rules may be stricter
Has State Law
Yes
Statewide Preemption Status Unconfirmed
No statewide preemption statute was confirmed for this jurisdiction — regulation is local. Local governments retain full authority to set their own rules.
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 · Source
DC allows ADUs by right in residential zones under 11 DCMR 1000 series provisions · Source
No owner-occupancy requirement — owners may rent both primary unit and ADU simultaneously · Source
No minimum parking required for ADUs — DC's transit access eliminates this requirement · Source
ADU permitting processed through DC Department of Buildings via DC Access online portal · Source
Historic preservation review required for properties in DC historic districts (approximately 30% of DC residential properties) · Source
DC does not impose development impact fees, reducing ADU cost compared to many cities · Source
Maximum one ADU per single-family lot in R-1 through R-4 zones · Source
Detached ADU maximum 1,000 sqft or 35% of primary unit floor area · Source
DC Zoning Commission periodically updates ADU provisions through formal rulemaking under Home Rule authority · Source
Legislative History
2016 — 11 DCMR Amendment — ADU Provisions · Source
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. · Source
2022 — 11 DCMR Amendment — ADU Expansion · Source
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. · Source
Official Sources
Source: DC Zoning Regulations Title 11 DCMR — Accessory Dwelling Unit Provisions. Last verified April 6, 2026. View source