5 county-level rules, plus city-specific rules for 3 cities in Montgomery County, Maryland.
Verified from official government sources
ZTA 19-01 (Oct 2019) allows ADUs by right in most residential zones. Max 1,200 sq ft or 50% of principal dwelling. No extra parking needed. Owner occupancy required.
Sheds up to 200 sq ft and one story are permit-exempt in MoCo but must meet setbacks under Zoning Section 59.3.6. Larger sheds need a DPS building permit.
Garage conversions in MoCo require a DPS building permit and must meet IRC habitable room standards. Replacement parking may be needed if the garage served a required space.
Carports over 200 sq ft need a DPS building permit under Zoning Section 59.3.6. Must be open on at least two sides or they are reclassified as garages.
No standalone tiny home ordinance in MoCo. Tiny homes on foundations may qualify as ADUs under ZTA 19-01. Tiny homes on wheels are classified as RVs, not dwellings.
3 cities in Montgomery County have their own accessory structures rules. Each link goes to that city's dedicated page with code citations.
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Montgomery County Ordinance Hub →