Before You Build in Gaithersburg, MD: Permit & Rule Checklist (2026)

Gaithersburg permits retaining walls where changes in street grade, width, or alignment make them necessary. Section 24-167 exempts retaining walls from the corner lot sight triangle restriction when they address grade changes. Retaining walls over 4 feet typically require a building permit and engineering review.

A Residential Fence Permit is required in Gaithersburg for all new fences and any additions or alterations to existing fences. Applications are submitted through the city permitting office and must comply with Chapter 24 zoning standards for height, location, and materials.

Outdoor swimming pools over 18 inches deep in Gaithersburg must be completely enclosed by an approved fence or wall at least 5 feet high. Gates must be self-closing and self-latching with the latch at least 4 feet from the ground on the pool side. Montgomery County Code Section 51-16 governs these requirements.

Gaithersburg Section 24-167 addresses shared property line fences. A side property line fence above 6 feet requires written consent from the adjoining property owner and city manager approval. Fences must be installed on or inside the property line, not on the neighbors land.

Gaithersburg Chapter 24 (Zoning) Section 24-167 limits fences to 3 feet in the front yard and 6 feet in the rear yard along public rights-of-way. Side property line fences are limited to 6 feet unless the adjoining owner provides written consent for a taller fence.

All swimming pools in Gaithersburg require a building permit from the City of Gaithersburg Permitting and Inspections Division before any construction or installation work begins. This requirement applies to in-ground pools, above-ground pools deeper than 24 inches, and permanently installed hot tubs and spas. A fence/barrier permit must be obtained simultaneously with the pool permit to ensure compliance with Montgomery County Code Chapter 51 safety barrier requirements. Separate electrical permits are required for pool pumps, heaters, underwater lighting, and GFCI-protected outlet installations, and all electrical work must be performed by a Maryland-licensed electrician. Plumbing permits may be needed for pool drain connections, water supply lines, and backflow prevention devices. The permit application requires submission of a site plan showing the pool location, setbacks from all property lines, the proposed barrier/fence location and specifications, electrical connection points, and drainage provisions. The city requires inspections at multiple construction stages including excavation, structural reinforcement, plumbing rough-in, electrical rough-in, barrier installation, and final completion. WSSC may require a separate fill permit or connection permit for initial pool filling. Processing time for pool permits is typically 10 to 20 business days from complete application submission.

Above-ground pools in Gaithersburg require a building permit if the water depth exceeds 24 inches. The same barrier and safety requirements that apply to in-ground pools apply to above-ground models. Pools must be set back from property lines per zoning district requirements and must not be placed in easements or over underground utilities.

Swimming pools in Gaithersburg capable of holding water more than 18 inches deep must be completely enclosed by a safety barrier at least 60 inches (5 feet) high under Montgomery County Code Chapter 51 (Section 51-15). This requirement applies to all pools constructed or installed after January 1, 1990, including both in-ground and above-ground pools. The barrier may consist of a fence, wall, building wall, or any combination that completely surrounds the pool area. Gates within the barrier must be self-closing and self-latching, with the latch mechanism located on the pool side of the gate at a minimum height of 48 inches (54 inches recommended) above the ground. Pedestrian access gates must swing outward, away from the pool. Fence openings must not permit passage of a 4-inch diameter sphere, which prevents small children from squeezing through gaps. For houses where an exterior door opens directly from the dwelling into the pool area, that door must be equipped with an audible alarm that sounds when opened, or the pool must be protected by an approved automatic safety cover meeting ASTM F1346 standards. Above-ground pools with non-climbable sides at least 48 inches high may use the pool wall as part of the required barrier, but access ladders and steps must be removable, lockable, or gated to prevent unsupervised child access.

Gaithersburg enforces pool safety rules through its building code and Montgomery County regulations. All residential pools must have barrier fencing at least 48 inches high with self-closing, self-latching gates. Drain entrapment protections compliant with the Virginia Graeme Baker Act are required. Pool owners must maintain safety equipment on site at all times.

Hot tubs and spas in Gaithersburg require an electrical permit for the dedicated circuit installation. Units with water depth exceeding 24 inches must meet barrier requirements. Hot tubs must have a locking safety cover compliant with ASTM F1346. Placement must comply with rear-yard setback requirements and cannot be in easements.

Converting a garage to living space in Gaithersburg requires a building permit and zoning review. The conversion must meet residential building code standards for habitable space including egress, insulation, ventilation, and ceiling height. Off-street parking requirements must still be satisfied after the conversion. Garage-to-ADU conversions follow the city's accessory dwelling unit regulations.

Gaithersburg permits accessory dwelling units in most residential zones following its ADU-friendly zoning amendments. ADUs may be attached to or detached from the primary dwelling. Units are limited to 50 percent of the primary dwelling floor area or 1,200 square feet, whichever is less. One off-street parking space is required. Owner occupancy of either the primary or accessory unit is required.

Tiny homes in Gaithersburg must comply with the International Residential Code minimum standards for dwelling units. Tiny homes on foundations may qualify as accessory dwelling units subject to ADU regulations. Tiny homes on wheels are classified as recreational vehicles and cannot be used as permanent residences. Minimum dwelling unit size is generally 150 square feet under the IRC Appendix Q provisions.

Storage sheds in Gaithersburg are regulated by the city's zoning ordinance and building code. Sheds under 200 square feet do not require a building permit but must comply with setback and height requirements. Sheds 200 square feet or larger require a building permit. All sheds must be in rear yards and set back at least 3 feet from property lines in most residential zones.

Carports in Gaithersburg are treated as accessory structures and require a building permit. They must meet setback requirements for the applicable zoning district. Carports may be attached or detached from the primary dwelling. Front-yard carports are generally not permitted in single-family residential zones unless approved through the site plan process.

Open outdoor burning is generally prohibited in Gaithersburg under Montgomery County regulations and the Maryland Fire Prevention Code. Recreational fires in approved fire pits are the primary exception. Burning of yard waste, leaves, trash, and construction debris is banned. The county may issue additional burn bans during high-risk conditions.

Gaithersburg permits recreational fire pits under Maryland Fire Prevention Code and Montgomery County fire regulations. Fire pits must be at least 15 feet from structures, property lines, and combustible materials. Only clean dry wood or gas fuel is permitted. A means of extinguishment must be readily available.

Gaithersburg enforces the Montgomery County Forest Conservation Law (Chapter 22A), the Roadside Tree Law (Chapter 49), and the Tree Canopy Law (Chapter 55), creating one of the strongest tree protection frameworks in the Washington DC metropolitan area. Permits are required for removing roadside trees or any trees on properties subject to active forest conservation plans. Development projects must meet specific tree canopy coverage targets, and the county has established a long-term goal of achieving 70 percent tree canopy coverage countywide. The Forest Conservation Law applies to all development activity on lots of 40,000 square feet (roughly one acre) or larger and requires submission and approval of a forest conservation plan before any clearing or grading begins. The Tree Canopy Law (Chapter 55) requires new subdivision and site plan development to plant or preserve a minimum percentage of tree canopy based on the zoning district. For individual residential lots under 40,000 square feet, a property owner may generally remove a private tree without a county permit, but HOA covenants, site plan conditions, and any recorded forest conservation easements may impose additional restrictions that survive from the original development approval.

Gaithersburg is served by WSSC Water (Washington Suburban Sanitary Commission), the bi-county water and sewer utility for Montgomery and Prince George's counties. Mandatory outdoor watering restrictions activate during drought emergencies declared by the Maryland Department of the Environment (MDE) under COMAR 26.03.04. Outside of declared drought conditions, no permanent watering schedule is imposed on Gaithersburg residents, unlike many western and southern cities that enforce year-round irrigation schedules. During a drought watch, voluntary conservation is requested. During a drought warning, odd-even address watering schedules may take effect. During a full drought emergency, all non-essential outdoor water use is prohibited, including lawn irrigation, car washing, and filling swimming pools. WSSC may also impose excess-use surcharges during declared emergencies. Gaithersburg falls entirely within the Chesapeake Bay watershed, which adds an environmental conservation dimension to all water management and fertilizer policies under the Maryland Fertilizer Use Act of 2011.

Trees overhanging public sidewalks and streets in Gaithersburg must maintain a minimum clearance of 8 feet above sidewalks and 14 feet above streets to ensure safe passage for pedestrians and vehicles. Property owners are responsible for trimming their own trees that encroach into these clearance zones, even if the trunk is on private property. Roadside trees planted within the public right-of-way along county-maintained roads are regulated under Montgomery County Code Chapter 49 (Roadside Trees) and require a permit from the county Department of Transportation before any cutting, trimming, or removal work is performed. A concurrent permit from the Maryland Department of Natural Resources is also required for roadside tree work under the state Roadside Tree Law (Natural Resources Article 5-406). Private trees on residential property can generally be trimmed without a government permit, as long as the work does not kill the tree and does not involve a specimen tree protected under the Forest Conservation Law (Chapter 22A). Utility companies including Pepco and BGE maintain their own trimming rights along power line corridors.