ADU Rules in Ellicott City, Maryland

Ellicott City is an unincorporated community in Howard County, Maryland — the county seat of Howard County. There is no incorporated City of Ellicott City. All zoning and permitting is handled by Howard County. The historic downtown on the Patapsco River was devastated by catastrophic flash floods in July 2016 and again in May 2018, prompting major revisions to Howard County's floodplain and development regulations. Flood zone and stormwater requirements are a critical context for any development in or near Ellicott City.

CRITICAL: No City of Ellicott City Government

Ellicott City is NOT an incorporated city. All ADU permits, zoning questions, and inspections go through:

• Howard County Department of Planning and Zoning
• Howard County Department of Inspections, Licenses and Permits

CRITICAL: Post-Flood Development Regulations

The 2016 and 2018 floods caused catastrophic damage to Ellicott City's historic Main Street. Howard County has:

• Revised floodplain management regulations
• Implemented enhanced stormwater management requirements
• May have acquired flood-prone properties (some were demolished)
• Check current flood zone maps — they may differ significantly from pre-2018 maps

Before planning any ADU in Ellicott City, verify current flood zone status and post-flood regulations with Howard County.

Howard County ADU Rules

Howard County's Zoning Regulations govern ADUs in Ellicott City. Verify current ADU requirements with the Howard County Department of Planning and Zoning.

Permitted ADU Types

Per Howard County Zoning Regulations (verify current standards):

• Accessory apartments: Within or attached to primary structure
• Detached ADUs: Subject to Howard County standards

Verify current provisions with Howard County Department of Planning and Zoning.

Setbacks

Per Howard County residential zone:

• Rear: Minimum setback
• Side: Minimum setback

Floodplain and Stormwater

Properties anywhere near the Patapsco River, Tiber Branch, New Cut Road area, or Main Street may be in FEMA flood zones or subject to enhanced Howard County stormwater management requirements. Verify flood zone status before any investment.

Historic Ellicott City

Historic Ellicott City is on the National Register of Historic Places. Properties in the historic district require review — contact Howard County Historic Preservation office for exterior modification requirements.

Chesapeake Bay Critical Area

Properties within 1,000 feet of the Patapsco River (tidal portion) may be in Maryland's Critical Area. Verify Critical Area status.

Permit Process

1. Verify flood zone status: This is critical — check current FEMA maps with Howard County
2. Verify zoning: Howard County Dept. of Planning and Zoning
3. Historic review: If in the historic district
4. Stormwater review: Required for most new construction in Ellicott City area
5. Submit plans: Howard County Dept. of Inspections, Licenses and Permits
6. Building permit and inspections
7. CO: Required before occupancy

Contact

Howard County Department of Planning and Zoning 3430 Courthouse Drive, Ellicott City, MD 21043 Phone: (410) 313-2350 Website: howardcountymd.gov/planning-and-zoning

Disclaimer: There is no City of Ellicott City — Howard County governs. Post-2018 flood regulations significantly changed development requirements near the Patapsco River and Main Street. Verify current flood zone status and regulations before starting any project.