Maryland Garage Permits: What You Need to Know

Maryland's Statewide Building Code: A Consistent Baseline

Unlike states that leave code adoption entirely to local governments, Maryland enforces a unified statewide building code called the Maryland Building Performance Standards (MBPS). The MBPS requires every jurisdiction in the state to use the same edition of the International Building Code, the International Residential Code (IRC), and the International Energy Conservation Code (IECC). The Maryland Codes Administration, within the Department of Labor's Division of Labor and Industry, is the statewide adopting authority.

The current MBPS is based on the 2018 editions of the ICC codes with state modifications. Some jurisdictions, notably Montgomery County, have adopted the 2021 editions. Local jurisdictions can amend the state codes to suit local conditions, but they cannot adopt weaker codes. The energy code and accessibility code are exempt from home rule provisions, meaning local jurisdictions can only make those codes more stringent.

This statewide uniformity means the basic permit requirement for garages is consistent across Maryland: you need a building permit for any garage, attached or detached, in virtually every jurisdiction. The fees, review times, and specific local amendments vary, but the code foundation is the same.

For a broader look at garage permit rules across the country, see our national guide to garage permits.

The EV Charging Mandate: Maryland's Unique Requirement

Maryland is among the first states to require electric vehicle charging infrastructure in new residential construction. House Bill 830, effective October 1, 2023, requires all new single-family homes, townhouses, and duplexes to include either one installed Level 2 EV charger or one EV-ready parking space in the garage, carport, or driveway.

This law applies statewide and affects garage construction in two ways. First, if the garage is part of new home construction, the electrical plans must include EV charging infrastructure, which adds cost for the dedicated 240-volt circuit, conduit, and panel capacity. Second, even when building a standalone new garage for an existing home, many homeowners are choosing to include EV wiring during construction to avoid the higher cost of retrofitting later.

The law does not retroactively require EV charging in existing garages, but it is a factor to consider when planning new garage construction in Maryland.

Attached vs. Detached Garages

Both attached and detached garages require building permits throughout Maryland. The construction requirements differ based on the type.

An attached garage must meet fire separation requirements between the garage and living space, requires a full foundation extending to the local frost depth, and the structural connection to the house must be properly engineered. Attached garages are treated as part of the dwelling and must comply with the full IRC requirements for fire separation, structural integrity, and energy code.

A detached garage sits on its own foundation. In most Maryland counties, detached garages require a building permit regardless of size. Some counties, like Baltimore County, exempt accessory structures under 120 square feet from permits, but garages nearly always exceed this threshold. Howard County does not require a permit for detached structures under 200 square feet. Prince George's County requires a permit and structural plans for all garages.

In Gaithersburg, the City of Gaithersburg specifies that attached garages must be separated from the home living area by a minimum of 1/2-inch Type X drywall for walls and 5/8-inch Type X drywall for ceilings.

Fire Separation Requirements

Maryland follows the IRC's fire separation standards as adopted through the MBPS. For attached garages, the wall separating the garage from the living space must be covered with at least 1/2-inch Type X gypsum board on the garage side. If habitable rooms are above the garage, the ceiling must use 5/8-inch Type X gypsum board.

The door between the garage and the house must be a solid wood door at least 1-3/8 inches thick, a solid or honeycomb-core steel door of equal thickness, or a 20-minute fire-rated door. All garage-to-house doors must be self-closing. No door from the garage may open directly into a sleeping room.

For detached garages, fire separation from the house is generally not required unless the detached structure is within 3 feet of the dwelling. In that case, the same fire separation standards apply.

How Maryland Counties Handle Garage Permits

Baltimore City and Baltimore County

Baltimore City requires a building permit for any garage construction. Baltimore County requires permits for all accessory structures greater than 120 square feet, and for any accessory structure regardless of size if it is located in a designated historic district or on agricultural property requiring verification. Baltimore County processes permits through an online portal where applicants can view comments, upload revised documents, track permit status, and pay fees electronically.

Permit fees in Baltimore and Baltimore County are valuation-based, typically ranging from $200 to $700 or more for a standard garage. Review times average 10 to 20 business days. Baltimore County accepts Mastercard, Visa, and PayPal for electronic payments. Once all reviews are completed and approved, the permit is issued and the applicant is notified via email. Permits and approved plans must be available at the job site for inspections, and all construction must be completed exactly as stated on the approved plans.

Baltimore City's older rowhouse neighborhoods present unique challenges for garage construction. Many properties have limited rear yard space and narrow alley access. Setback compliance, lot coverage limits, and alley access width are common issues that must be resolved during the zoning review.

Prince George's County

Prince George's County, one of Maryland's most populous counties, requires a building permit for all garages, whether attached or detached. The county's Department of Permitting, Inspections, and Enforcement handles garage permits through its Momentum online portal.

Bowie and other Prince George's County cities follow the county's permitting process. Structural plans are required for all garage projects. If the garage requires changes to an existing driveway apron or a new driveway apron, a separate permit is required. Electrical work in attached garages requires an application for an electrical permit by a Master Electrician licensed by the State of Maryland. The county explicitly notes that details and restrictions for garages also apply to covered or enclosed boat storage facilities on residential lots.

If your property is in a subdivision with a Homeowners Association, a separate approval from the HOA may be necessary before applying for the county permit. Prince George's County is one of the most HOA-dense areas in Maryland, and many subdivisions have detailed architectural review requirements for garages.

Montgomery County

Montgomery County, through its Department of Permitting Services (DPS), has adopted some of the most up-to-date building codes in Maryland, including the 2021 IRC and 2021 IECC. The county's residential construction code page provides listings of codes, standards, and local policy interpretations that affect garage construction.

Review times for residential garage permits in Montgomery County typically run 10 to 20 business days. Permit fees are valuation-based. Montgomery County has extensive environmental regulations, including stormwater management requirements and forest conservation laws that may affect garage projects on larger lots. The county's proximity to Washington, DC means construction costs and labor rates are among the highest in Maryland.

Foundation Requirements

Maryland's frost depth ranges from approximately 24 inches on the Eastern Shore and coastal areas to 30 inches or more in the western mountain counties. Most of central Maryland, including the Baltimore metro area and Washington DC suburbs, uses a 30-inch frost depth.

Garage foundations must extend below the frost line. Harford County specifies that garages must have foundation anchorage with 1/2-inch diameter anchor bolts embedded at least 8 inches in poured concrete walls and 15 inches in grouted masonry walls. Anchors must be spaced no more than 6 feet apart and placed within 12 inches of all foundation corners.

Garage floor slabs must be at least 4 inches of concrete on 4 inches of crushed stone. The building site must be well-drained. Many Maryland counties require a frost-protected footing and foundation of masonry as piers or a continuous wall extending 30 inches below final grade.

MHIC Licensing: A State Requirement

Maryland requires all contractors performing home improvement work to be licensed by the Maryland Home Improvement Commission (MHIC). This includes garage construction, additions, and conversions. The MHIC has specific requirements for the form and content of every home improvement contract.

For new home construction that includes a garage, the builder must be registered with the Maryland Home Builder Registration Unit (MHBR). These licensing requirements apply statewide and are in addition to any local contractor registration.

Homeowners may perform some work themselves, but electrical work must be performed by a state-licensed master electrician. Before signing any home improvement contract for a garage project, verify the contractor's MHIC license status.

Chesapeake Bay Critical Area Considerations

Properties near the Chesapeake Bay and its tributaries may be subject to Maryland's Critical Area laws, which restrict development within 1,000 feet of tidal waters and tidal wetlands. These restrictions can affect garage construction by limiting impervious surface coverage, requiring stormwater management measures, and imposing additional setbacks.

Even small projects that might not ordinarily require a building permit, such as driveways and patio areas, must be reviewed for Critical Area compliance on waterfront properties. If your property is within the Critical Area, expect additional review steps and potentially longer processing times for your garage permit.

Electrical Requirements

Garage electrical work in Maryland requires a separate electrical permit pulled by a licensed master electrician. At minimum, a new garage needs circuits for lighting, a garage door opener, and at least one GFCI-protected receptacle.

For EV charger installations, the electrical plans must show the dedicated circuit, panel capacity, and conduit routing. Level 2 chargers require a 240-volt dedicated circuit. Maryland's EV-ready building requirement for new homes means the electrical infrastructure for EV charging should be included in new garage electrical plans from the start.

Garage Conversions

Converting a garage to living space requires a building permit in every Maryland jurisdiction. The conversion triggers current energy code requirements, egress window standards, and mechanical system upgrades. Many Maryland counties require that minimum off-street parking be maintained, so a conversion may require a zoning variance or construction of replacement parking.

Montgomery County and Prince George's County both have specific regulations governing garage conversions. Contact your county's permitting department early in the planning process to understand the full scope of requirements.

Consequences of Building Without a Permit

Maryland takes unpermitted construction seriously. Consequences include stop-work orders, fines, doubled permit fees for retroactive applications, and complications during home sales. Many Maryland counties charge increased permit costs for construction that begins without a permit, and some require the structure to be deconstructed in part or whole to allow proper inspections.

Garrett County notes that building permits last one year, and construction that does not begin within that period voids the permit. After construction begins, a permit can also be voided if there is no activity for over a year.

For home sales, unpermitted garages frequently surface during inspections and appraisals. Maryland title companies and lenders routinely flag unpermitted work, which can delay or derail a sale.

If you are also planning a shed, fence, or deck alongside your garage, check whether your county allows bundled permit applications. For an overview of all building permit requirements in Maryland, including patios and other project types, see our complete Maryland building permit guide.