ADU Laws And Permit Requirements in Maryland: What You Need to Know

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ADU Laws And Permit Requirements in Maryland: What You Need to Know

Maryland homeowners face significant changes ahead as new legislation reshapes the space for accessory dwelling units. The Maryland General Assembly has passed new legislation, specifically Senate Bill 891 and House Bill 1466, collectively known as the Accessory Dwelling Units Act of 2025. These laws will transform how property owners utilize their residential spaces, creating additional housing opportunities throughout the state.

At Doug Pruett Construction Company, we are one of the region's preferred residential and commercial remodeling companies. We always stay up to date with new laws and legislation related to our field, and you can expect code-compliant structures from us.

The bill will take effect on October 1, 2025, and applies to charter counties and the City of Baltimore. Local jurisdictions have one year to comply with this requirement. By October 1, 2026, all local legislative bodies need to adopt new laws authorizing the development of Accessory Dwelling Units. The mentioned timeline creates the need for urgency for local municipalities to establish the required regulatory frameworks.

The legislation defines ADU's with specific parameters. ADUs are secondary dwelling units located on the same lot as a primary single-family dwelling and not exceeding 75% of the size of the primary unit. This size restriction ensures units remain secondary in nature while providing meaningful living space.

Types of Accessory Dwelling Units

Property owners can choose from several ADU configurations. Detached units function as standalone structures separate from the main house. These provide maximum privacy and independence. Attached units share at least one wall with the primary residence.

This design offers convenient access while maintaining separation. Conversion projects transform existing spaces. Garages frequently become living areas through strategic renovation. Basements present another conversion opportunity. These projects often require less construction than new builds.

Permit Requirements and Approval Process

The permitting process varies by jurisdiction, and different counties and municipalities will establish their own specific requirements. Montgomery County provides detailed guidelines for current ADU applications. These include zoning compliance reviews and building code inspections.
Building permits remain mandatory for all ADU projects. Electrical, plumbing, and structural work requires professional oversight. Safety codes apply equally to accessory units and primary residences, and fire safety measures receive particular attention during inspections.

Setback requirements limit the placement of units. Height restrictions affect design possibilities. Parking requirements often mandate additional spaces. These regulations prevent overcrowding and maintain neighborhood character.

Homeowners Association Considerations

The legislation aims to address housing needs by making it easier for homeowners to create additional living spaces on their properties. However, homeowners' association rules may develop complications. The new law addresses this concern directly. The main provisions include a standard statewide policy framework that prohibits unreasonable restrictions and adjusts HOA rules to accommodate ADUs.
Review your HOA covenants before beginning any ADU project. Some associations may need to modify their restrictions. Legal consultation can help navigate these potential conflicts.

ADUs represent significant investments with multiple benefits. These units typically increase overall property values. Rental income provides ongoing financial returns. Construction costs vary widely based on unit type and local labor markets.

Detached units require the highest initial investment. Conversion projects often cost less but may have limitations. Financing options include home equity loans and construction loans. Some lenders offer specialized ADU financing programs.

Zoning And Land Use Compliance

Zoning classifications determine ADU eligibility. Single-family residential zones generally permit these units under the new law. Mixed-use areas may have different requirements, while commercial zones typically prohibit residential ADUs.
Lot size affects ADU feasibility, and minimum lot dimensions vary by jurisdiction. Some areas require specific lot coverage ratios. These restrictions prevent over-development of small parcels.

Implementation Timeline and Next Steps

The October 2025 effective date approaches rapidly, and property owners should begin planning now for potential projects. Local governments are developing their specific ordinances and procedures. Contact your municipal planning department for current information, as regulations will continue to evolve as jurisdictions implement the new law. Early consultation prevents costly mistakes during the approval process as professional assistance proves valuable for complex projects.

When we handle your ADU construction project, we follow all the necessary codes and assist with getting the permits. For more details, please call Doug Pruett Construction Company at 410-224-4057. You can also send us your queries via this Online Form, and one of our experts will get back to you shortly.

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