Accessory Structures in Rockville, MD (2026)
5 verified accessory structures rules for Rockville, Maryland, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
A detached Accessory Dwelling Unit in Rockville must sit on a permanent foundation and stay at or under 75% of the main house's floor area, or up to 600 square feet if that house is under 800 square feet.
Rockville Detached ADU Size Limits
Some RestrictionsRockville City Code § 25.6.3.6(b)(3)
B. Detached Accessory Dwelling Units must be permanently attached to the ground by a foundation. C. Size limitation. Detached Accessory Dwelling Units may have a gross floor area: 1. If the principal dwelling unit has a gross floor area of 800 square feet or more, equal to or less than 75 percent of the total floor area of the principal ...
ADU Owner Occupancy
Owners of a Rockville one-family home with an accessory-apartment special exception must certify annually where they live and whether any part of the house is rented.
Rockville Accessory Apartment Owner Certification
Significant RestrictionsRockville City Code § 5-287 (adopting IPMC § 301.2.6)
301.2.6 Accessory apartments. The owner of a one-family dwelling in which there is an accessory apartment for which a special exception has been granted must: (a) Certify annually on a form provided by the Division of Inspection Services: (i) where the owner of the dwelling resides; and (ii) whether or not any portion of the structure ... is rented. (b) Permit periodic inspections by the Divisi...
ADU Rental Restrictions
Rockville, Maryland bars a landlord from holding rental licenses for both a house and its accessory apartment at once: only one of the two units on a lot may be licensed for rent at a time.
Rockville Accessory Apartment Rental License Limits
Significant RestrictionsRockville City Code § 18-112(3)–(4)
Where a single dwelling unit contains, or is attached to an accessory apartment, a single dwelling unit rental license may only be issued for that part of the building excluding the accessory apartment. In no case may a rental license be issued for a single dwelling unit and for an accessory apartment on the same lot;(4)Accessory apartment rental unit license. No license may be issued for an ac...
Shed & Carport Rules
Rockville zoning treats a carport as an accessory structure: it can't share a wall or roof with the house except through a short breezeway, and a detached carport must sit in the rear yard within set height and footprint caps.
Rockville Carport Placement Standards
Some RestrictionsRockville City Code § 25.8.1.3(b)
Accessory buildings and structures must be customarily associated with, and clearly incidental and subordinate to, a legally established principal structure. Attaching these structures to the main building by any part of a common wall or common roof is prohibited, except as follows: (1) One accessory building on a lot may be connected to a main building by an open, unenclosed breezeway no more ...
Tiny Homes
Rockville's residential code adopts IRC Appendix Q in full, giving tiny houses their own building standard instead of full-size dwelling rules.
Rockville Adopts IRC Appendix Q Tiny Houses
Some RestrictionsRockville City Code § 5-102
Appendix Q Tiny Houses of the IRC is adopted in its entirety. (Ord. No. 11-15, § 6, 6-1-15; Ord. No. 8-18, § 2, 5-14-18; Ord. No. 22-19, § 6, 9-9-19; Ord. No. 6-24, § I, 5-20-24) Secs. 5-103—5-110. - Reserved.
Looking for Montgomery County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Rockville city rules.
Accessory Structures in Montgomery County →