ADU Rules in Baltimore, MD (2026)
ADU rules, permit requirements, size limits, and fees for Baltimore, MD. Source-cited from official municipal code.
Yes, ADUs are allowed in Baltimore, MD.
Baltimore, MD permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. State and local law governs the approval process. In Baltimore, the Baltimore City Department of Housing and Community Development (DHCD) — Permits and Inspections handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in Baltimore.
ADU Size Limits
ADU Size Limits in Baltimore: Detached ADU: up to 800 sq ft (max height: 20 feet). Attached ADU: 35% of primary dwelling floor area. Baltimore allows accessory dwelling units as part of its housing diversity strategy. Maximum 800 sqft for detached units. JADU is a California-specific concept — not applicable in Baltimore.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | 800 sq ft | 20 feet |
| Attached ADU | 35% of primary dwelling floor area | Per zone height limit |
Permit Fees
ADU Permit Fees in Baltimore: Plan check fee: $200–$800. Building permit fee: Based on construction value — typically $800–$3,000. Impact fees: None. School fees: None or N/A. Total estimated permit cost: $1,500–$5,000 total permit fees. Baltimore City does not charge development impact fees for residential ADU scale projects. DHCD may offer grant programs for eligible ADU conversions.
| Fee Type | Amount |
|---|---|
| Plan Check | $200–$800 |
| Building Permit | Based on construction value — typically $800–$3,000 |
| Impact Fees | None |
| School Fees | None |
| Total Estimate | $1,500–$5,000 total permit fees |
Permit Timeline
Baltimore ADU Permit Timeline: Baltimore City permit: typically 4-8 weeks via online permit system. Baltimore City Department of Housing and Community Development (DHCD) also has programs supporting ADU construction. Apply through the Baltimore City Department of Housing and Community Development (DHCD) — Permits and Inspections online permit portal. Phone: (410) 396-3360.
Setback Requirements
ADU Setback Requirements in Baltimore: Front setback: follows zone standard. Side setback: 3 feet. Rear setback: 5 feet. Baltimore minimum accessory structure setbacks: 5 ft rear, 3 ft side. Many Baltimore rowhouse lots are narrow and deep — ADUs typically placed in rear yards, often as carriage house conversions.
Parking Requirements
Parking Requirements: No additional parking required for accessory dwelling units in Baltimore City. Baltimore's transit access and walkable neighborhoods support parking-free ADU policy.
Restrictions & Requirements
- ADU must meet Baltimore City Zoning Code accessory use standards
- Only one accessory dwelling unit per lot
- Cannot be located in required front yard
- Cannot be separately conveyed from primary dwelling
- Must maintain minimum lot coverage limits per zone
- Lead paint and asbestos remediation required for older properties
How Many ADUs Are Allowed?
Number of ADUs Allowed in Baltimore: Single-family lots: 1. Multifamily properties: Multiple units in R-6 through R-10 and higher density zones per development standards. One ADU per single-family lot. Baltimore's housing policy emphasizes preserving and adding to its rowhome stock.
Single-Family Lots
1
Multifamily Properties
Multiple units in R-6 through R-10 and higher density zones per development standards
Historic District Considerations
Historic District Requirements: Baltimore has 22 historic districts where additional design review may be required for ADU construction. Design review approval is required before obtaining a building permit for properties in historic overlay zones. Baltimore has extensive historic district protections reflecting its role as one of the oldest major American cities. Key districts include Fells Point (oldest neighborhood), Federal Hill, Bolton Hill, Roland Park, Reservoir Hill, Mount Vernon Cultural District, and Jonestown. Baltimore's Commission for Historical and Architectural Preservation (CHAP) reviews exterior alterations in 22+ locally designated districts and National Register Historic Districts. Baltimore's brick rowhouse architecture is a defining feature — material changes require review in historic areas. Look up historic district boundaries at: https://planning.baltimorecity.gov/historic-preservation
Frequently Asked Questions
Can I build an ADU in Baltimore?
Yes. Baltimore, MD allows accessory dwelling units. On a single-family lot you can build 1.
How big can an ADU be in Baltimore?
The maximum size for a detached ADU in Baltimore is 800 square feet.
How long does it take to get an ADU permit in Baltimore?
The typical ADU permit timeline in Baltimore is Baltimore City permit: typically 4-8 weeks via online permit system. Baltimore City Department of Housing and Community Development (DHCD) also has programs supporting ADU construction.. Total estimated permit fees are $1,500–$5,000 total permit fees.
Do I need extra parking for an ADU in Baltimore?
No, Baltimore does not require additional parking for ADUs.
Do I have to live on-site to have an ADU in Baltimore?
No, owner-occupancy is not required for ADUs in Baltimore.
Source: Baltimore City Zoning Code (2017 Rewrite); DHCD Housing Programs. Last verified April 6, 2026. View source