Tiny House as ADU

Montgomery (County), Maryland


Name Tiny House as ADU
Municipality Montgomery (County)
Zoning Districts Generally, zones that permit Residential Uses
Effective Date 12/31/2019
Municipal Code Section 3.3.3. Accessory Residential Uses
Code Link https://codelibrary.amlegal.com/codes/montgomerycounty/latest/montgomeryco_md_zone2014/0-0-0-1110
Authority Department of Housing and Community Affairs


Are ADUs, including “tiny houses,” already allowed in Montgomery County?
Yes, they are. They can be built in, or as an addition to, an existing home and as a detached unit on lots of one acre or more. There are 414 licensed ADUs in the County; 356 of them (86 percent) are in the County’s smaller-lot residential zones found in areas like Wheaton, Silver Spring, Aspen Hill, Bethesda, Kensington, Takoma Park, Colesville, and Germantown. There are also unlicensed ADUs, but the County does not know how many.

To learn more about ADUs or to apply for an ADU license, visit the DHCA Licensing and Registration Class 3 Accessory Dwelling Unit webpage or call 311 (240-777-0311).

New information about Accessory Dwelling Units (ADUs), such as a basement apartment, in-law suite or tiny home, is now available on the Montgomery County website and by calling 311. The information reflects changes in the County’s Zoning Text Amendment 19-01 that take effect on Tuesday, Dec. 31.

An ADU is a housing unit located on the same lot as a single-family detached house – subject to specific legal requirements.  An ADU is not permitted in a townhouse, condo, duplex or mobile home and may not be used as a short-term vacation rental.

To ensure compliance with health and safety laws, all existing ADUs and proposed ADUs must be licensed with the Montgomery County Department of Housing and Community Affairs (DHCA).  ADUs are inspected at licensure application for compliance with County housing and zoning codes. Required building permits are issued by the Department of Permitting Services.

ADUs located within the following municipalities are not required to be licensed with DHCA: Town of Laytonsville, Town of Barnesville, Town of Garrett Park, Villages of North Chevy Chase, City of Rockville and City of Gaithersburg. Homeowners in the City of Takoma Park must obtain a one-time ADU license issued by DHCA and maintain a renewable rental license with the City of Takoma Park.

Homeowners with a unit previously licensed with DHCA as an “accessory apartment” will be reclassified as an ADU.


Key Contacts

Department of Housing and Community Affairs

Department of Housing and Community Affairs
1401 Rockville Pike, 4th Floor
Rockville, MD 20852




Information Sheet

Updated Nov 24 by Laura

THIA will be constantly updating the legislation data. Check back often. Suggest A Correction if you are aware of any missing or incorrect information. AND keep scrolling to learn more about getting guidance.



Building Code — Legislation that speaks to how to construct a tiny house.

Zoning Code — Legislation that speaks to how the lot will be used.


ADU — Accessory Dwelling Unit

DMV — Division of Motor Vehicles

IB — Industrialized Buildings

IRC — International Residential Code

PUD — Planned Unit Development

RV — Recreational Vehicle

SF — Single Family Dwelling

T — Transitional Housing

UDO — Unified Development Ordinance

Please Suggest a Correction if you find broken links or misinformation.

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