Rockville limits the percentage of a lot that may be covered by buildings and impervious surfaces. In single-family residential zones, building coverage is typically limited to 30% to 35% of lot area, with total impervious surface (including driveways and patios) capped at 45% to 55%. Exceeding coverage limits requires a variance from the Board of Appeals.
The City of Rockville Zoning Ordinance establishes maximum lot coverage standards to control density, preserve green space, and manage stormwater runoff. In the R-60 single-family zone, building coverage (the footprint of all roofed structures) is limited to approximately 35% of the total lot area. Total impervious surface coverage, which includes the building footprint plus driveways, sidewalks, patios, and other hardscaped areas, is typically capped at around 50% to 55% of the lot. The R-90 zone has lower coverage limits reflecting its larger-lot character, while the R-40 zone may allow slightly higher building coverage. Coverage calculations include the principal dwelling, attached and detached garages, covered porches, carports, sheds, and any other roofed structures. Open decks and certain permeable paving materials may be excluded from impervious surface calculations under specific conditions. The city's stormwater management requirements under Chapter 19 of the City Code impose additional controls on impervious surfaces, requiring on-site stormwater management for projects that increase impervious area beyond certain thresholds. This is particularly important in Rockville given the Chesapeake Bay watershed protection requirements. HOA communities may impose stricter lot coverage limits through their recorded covenants, particularly in newer planned developments. Contact the Department of Community Planning and Development Services at 240-314-8200 for coverage requirements and the Department of Public Works at 240-314-8500 for stormwater management questions.
Exceeding lot coverage limits without a variance is a zoning violation. The city may deny building permits for projects that exceed coverage limits. Existing coverage violations must be corrected or a variance obtained. Failure to comply with stormwater management requirements for impervious surfaces carries separate fines.
Rockville, MD
Construction noise in Rockville is permitted 7 AM to 7 PM weekdays and 9 AM to 5 PM weekends under MoCo Code Section 31B-6. Nighttime deliveries are prohibit...
Rockville, MD
Industrial noise in Rockville is regulated under MoCo Code Chapter 31B. Industrial limits are 75 dBA day, 70 dBA night. Equipment running 24 hours must meet ...
Rockville, MD
Rockville enforces noise limits under MoCo Code Chapter 31B. Daytime runs 7 AM to 9 PM weekdays, 9 AM to 9 PM weekends. Nighttime limit is 55 dBA at resident...
Rockville, MD
Rockville's animal control ordinance (Chapter 3) prohibits nuisance animal noise. Owners must prevent dogs from causing persistent noise that disturbs neighb...
Rockville, MD
Rockville sits between Reagan National and BWI but is outside both noise zones. Aircraft noise is federally regulated. The Maryland Environmental Noise Act o...
Rockville, MD
Maryland requires new homes after October 2023 to include EV-ready parking with a minimum 40-amp dedicated circuit. HOAs cannot prohibit charger installation.
Side-by-side rule comparisons with other cities in Montgomery County.
See how other cities in Montgomery County handle lot coverage limits.
See how Rockville's lot coverage limits rules stack up against other locations.
Quick Compare
Help us keep this page accurate. If you notice an error or outdated information, let us know.