Accessory Structures in Baltimore, MD: What Residents Actually Need to Know

If you live in Baltimore or are thinking about moving there, accessory structures are one of those things you probably won't think about until they affect you directly. Baltimore has 6 specific rules on the books covering different aspects of accessory structures, and some of them might surprise you.

Shed Rules

Baltimore Building Code Section 105.2 exempts one-story detached accessory structures used as tool/storage sheds or playhouses from a building permit when floor area is 120 sq ft or less. Article 32 Sec. 15-501 still limits height to 15 ft and rear-yard coverage to 50%.

Key details: Permit Threshold: 120 sq ft (Sec. 105.2). Max Height: 15 ft (Sec. 15-501). Rear Yard Coverage: 50% max. Setbacks: Per district yard rules. Same Lot Rule: Required (Sec. 15-501).

Sheds exceeding 120 sq ft, taller than 15 ft, encroaching into required setbacks, covering more than 50% of the required rear yard, or installed before the principal dwelling are Code violations enforceable by DHCD and the Zoning Administrator. Penalties include stop-work orders, citations, and orders to remove or modify the structure. Adding electrical or plumbing without trade permits triggers separate enforcement under the Building Code.

ADU Rules

Baltimore's Article 32 Zoning Code does not have a general 'ADU' use, but Section 15-504 allows existing carriage houses in any Residential or OR District to be converted into a single-family detached dwelling, treated as an accessory structure on the same lot.

Key details: Zoning Code: Article 32 (TransForm Baltimore). Carriage House: Sec. 15-504. Min Floor Area: 350 sq ft. Max Expansion: 20% height or footprint. Accessory Height: 15 ft (Sec. 15-501).

Building or converting a structure to a dwelling without permits and zoning approval is a Code violation enforced by the Department of Housing and Community Development; violators face stop-work orders, citations, and the requirement to remove or restore unpermitted work. Carriage-house conversions exceeding the 20% size or height expansion limit lose the Section 15-504 allowance.

ADU Owner Occupancy

Baltimore City does not require owner-occupancy for ADU properties under Article 32. Property owners may build an ADU and rent both the primary unit and ADU to separate tenants. Maryland HB 538 (2024) explicitly prohibits local owner-occupancy requirements for ADUs. HOA and condominium covenants may still impose owner-occupancy through declarations.

Key details: City Rule: No owner-occupancy required. State Preemption: MD HB 538 (2024). HOA Law: MD Real Prop. Art. §11B. Condo Law: MD Real Prop. Art. Title 11.

No city enforcement of owner-occupancy. HOA/condo association violations result in declaration-based fines, typically $50-$500 per violation, with lien rights for unpaid assessments. Civil litigation in Maryland Circuit Court is available for declaration enforcement. State preemption under HB 538 may invalidate certain HOA restrictions enacted after October 2024.

If you are coming from a city with tighter rules, you will find Baltimore gives residents more flexibility on adu owner occupancy.

ADU Impact Fees

Baltimore City does not charge development impact fees on residential ADUs. Only standard permit and plan-review fees apply through DHCD. Department of Public Works (DPW) charges water/sewer connection fees only when a new service line or meter is installed. Maryland does not authorize broad municipal impact fees, unlike California or Arizona.

Key details: Municipal Impact Fees: None. Building Permit: ~1-1.5% of construction. Utility Connection: Only if new service. Vacant Lot Pilot: Fee waivers possible.

Failure to pay permit fees blocks permit issuance and inspection scheduling. Bypassing fees through unpermitted construction triggers Article 32 Title 13 fines ($500/day) and Article 33 building code penalties. DHCD may place liens for unpaid fees. Unpaid utility connection fees may result in service refusal.

The rules around adu impact fees in Baltimore lean permissive, but that does not mean anything goes.

ADU Permits

Baltimore permits ADUs under the TransForm Baltimore Zoning Code (Article 32, adopted 2017). Detached and attached ADUs are allowed in R-1 through R-8 districts subject to dimensional standards. Permits route through the Department of Housing and Community Development (DHCD) and Building, Fire, and Related Codes Administration. Maryland HB 538 (2024) sets a statewide ADU framework that limits some restrictive local rules.

Key details: Code Authority: Article 32, Title 7. By-Right Zones: R-1 through R-8. Max Size: 700 sq ft or 35% primary. Max Height: 25 feet. State Framework: MD HB 538 (2024).

Unpermitted ADU construction violates Article 32 Title 13 (Enforcement). Penalties include stop-work orders, civil citations of $500 per violation per day under Section 13-303, and possible structure removal orders. DHCD can place liens on the property. Article 33 (Building Code) violations may also apply. Operating an unregistered ADU as a separate rental triggers separate violations under Article 13 (Housing).

ADU Rental Restrictions

Baltimore requires a Rental Property License under Article 13 (Housing Code) for every rental dwelling unit, including ADUs. Annual licensing through DHCD with inspections. Short-term rentals require separate STR license under Article 15, Subtitle 47. Maryland has no statewide rent control authorization; Baltimore City voters approved rent stabilization in November 2024 (CB 24-0470 framework, with implementation by DHCD).

Key details: Rental License: Required (Article 13). STR License: Article 15 Subtitle 47. Hotel Tax: 9.5% city + 6% state. Rent Stabilization: Approved 2024 (implementation). Lead Certification: Pre-1978 properties.

Operating without a rental license violates Article 13 with fines of $1,000 per occurrence and possible property condemnation. STR violations under Article 15, Subtitle 47 carry fines of $1,000 per day and listing removal. Failure to certify lead-safe creates separate state liability under MD Environment Article. Hotel tax non-remittance triggers state and city collection actions.

The Bottom Line

Compared to many U.S. cities, Baltimore gives residents more room on accessory structures. 2 of the 6 rules here are rated permissive. But permissive does not mean unregulated. There are still requirements, and the city does enforce them when violations are reported.

This guide is based on Baltimore's current municipal code. Local rules can and do change, so check the individual ordinance pages for the latest details, penalties, and FAQs.