Montgomery County requires DPS building permits for retaining walls over 4 feet in height or supporting a surcharge load. Engineered plans from a licensed PE are mandatory for walls over 4 feet. Stormwater management review is required in the Chesapeake Bay watershed under WSSC and DEP rules.
Montgomery County DPS requires a building permit for any retaining wall exceeding 4 feet in exposed height or supporting a surcharge load (driveway, structure, slope). Walls over 4 feet must include engineered plans stamped by a licensed Professional Engineer (PE) registered in Maryland. Retaining walls in Special Protection Areas (SPAs) or stream valley buffers require environmental review by the Department of Environmental Protection (DEP). The county follows the International Building Code (IBC) as adopted by Maryland for structural requirements including footing depth, drainage provisions, and soil bearing capacity. WSSC stormwater management approval is needed when retaining walls alter drainage patterns. Tiered retaining walls spaced less than the height of the lower wall apart are measured as a single wall for height calculations. Gabion walls, modular block, poured concrete, and timber walls are all acceptable materials if engineered properly. Walls within 5 feet of a property line require sediment control approval.
Unpermitted retaining wall: stop-work order and removal order from DPS. Fines up to $500 per day for continued violation. Failed wall causing drainage damage to neighbors: civil liability. SPA violations: DEP enforcement action with fines up to $10,000.
Montgomery County, MD
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