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The original item was published from 1/17/2020 8:21:17 AM to 1/27/2020 11:24:10 AM.

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Posted on: January 10, 2020

[ARCHIVED] County Council Adopts New Rules for Accessory Dwelling Units

The County Council adopted Zoning Text Amendment 19-01 (ZTA 19-01) “Accessory Residential Uses – Accessory Apartments” on July 23, 2019.  ZTA 19-01, which goes into effect on December 31, 2019, makes substantial changes to the rules governing “accessory dwelling units”, ADUs.  Zoning Text Amendments are the legislative device for changing the County’s Zoning Ordinance. 

The following material explains what an ADU is, what the new County rules for ADUs are, and ADUs within the Town.


What is an ADU? 
An ADU is a second dwelling unit located on a lot with a single-family house.  An ADU is subordinate to the house.  An attached ADU is one that is located inside the house, often in the basement.  A detached ADU is one that is in an accessory building in a rear yard (e.g., a converted garage, a “tiny” house, a granny pod, a pre-fabricated unit).  Currently, attached ADUs are allowed in all residential zones in the County, but detached ADUs are only allowed in “large lot” zones (1 acre or more minimum lot size).

What has the process been for making the zoning changes for ADUs? 
On February 14, 2019, the Planning Board considered ZTA 19-01 which specified the proposed changes to the rules that govern “ADUs.  On February 26, the County Council held a public hearing on the ZTA and then sent the ZTA to the Planning, Housing, and Economic Development (PHED) committee for consideration.  The PHED held three work sessions, recommended a number of amendments to the ZTA and sent it back to the County Council.  The County Council held work sessions on the ZTA on June 18 and on July 9, and unanimously voted to adopt it with amendments on July 23.  On July 16, the Council introduced companion Bill 22-19 Accessory Dwelling Units – Licensing Requirements-Amendments.  Bill 22-19 will amend the standards for minimum ceiling heights for basements or cellars used for ADUs and amend ADU licensing procedures.  A public hearing on Bill 19-22 is tentatively scheduled for September 10. The ZTA and Bill 19-22 will go into effect on December 31, 2019.

What problem is ZTA 19-01 trying to solve?
County Council member Hans Riemer introduced ZTA 19-01 to encourage the creation of more ADUs in single-family neighborhoods throughout the county.  Proponents of the ZTA see ADUs as a means of producing additional housing options, whether for extended families or as a source of supplemental income.  They also see ADUs as a means of increasing the supply of affordable housing, though there are no provisions in the ZTA to ensure affordability.

What are the most significant changes in the ADU rules?
ZTA 19-01 removes many of the current limits on creation of an attached ADU (see below).  The most significant change included in the ZTA is that, for the first time, detached ADUs will be allowed as a “Limited Use” in “small lot” neighborhoods like the Town (currently they are allowed as a limited use in “large lot” zones on lots of 1 acre or more).  Under the new rules, detached ADUs constructed in older buildings can have minimal or no setbacks from side and rear property lines.  In the Town, older garages often sit on or very close to the side and/or rear property lines.  Other significant changes are that greater density of ADUs will be allowed by right and both attached and detached ADUs will be allowed as part of new construction.

What are the County’s new ADU rules?

Rules for both Attached and Detached ADUs:

  • Both attached and detached ADUs will be allowed in the R-60 zone (all lots in the Town are zoned R-60).
  • One ADU (attached or detached) will be allowed per lot. The current distance separation requirement is being dropped.  This allows by right greater density of ADUs.
  • The property owner will be required to live either in the house or in the ADU.  This requirement will not be in the zoning code but will be a license requirement specified in Bill 19-22 discussed above.
  • A property with a licensed ADU cannot also get a license for short-term rentals (e.g., AirB&B).  After having an ADU for one year, the ADU license could be dropped and a license for a short-term rental unit obtained.  If that is done, the stove would have to be removed from the kitchen of the unit. Rentals of 30 days or less are considered to be short term.
  • A maximum of two adults can live in the ADU (the number of children allowed is regulated by county housing rules).
  • No off-street parking spaces will be required for ADUs in the Town because all lots are within a mile of Metro or Purple Line stations.

Rules for Attached ADUs

  • In most cases the size of an attached ADU will be limited to 1,200 square feet.  An attached ADU can be larger if located in the basement or cellar of the house and that basement or cellar is larger than 1,200 square feet.
  • The door for an attached ADU will have to be on the side or rear of the house, unless a second door already exists on the front of the house, or the house and ADU share an entrance.
  • Attached ADUs will be allowed in houses of any age (no longer just allowed in houses older than 5 years

Rules for Detached ADUs

  • The size of a detached ADU will be limited to the least of:
    • 50% of the footprint of the house;
    • 10% of the lot area; or
    • 1,200 square feet of gross floor area.
  • The maximum height of a detached ADU will be 20 feet. (Note that the Town does not allow the height of an accessory building to exceed 15 feet.)
  • There will be no setback requirements for a detached ADU located in an accessory building built before May 31, 2012.  If an existing building is enlarged (e.g., footprint or height changed), then it will be considered to be a new building and setbacks required for a new detached ADU will apply.
  • A detached ADU located in an accessory building built after May 30, 2012, must have a side setback at least as great as that required for a house and a rear setback of at least 12 feet.  The County will require a larger setback for detached ADUs with a wall-length greater than 24 feet (an extra foot of setback for each foot of wall length over 24 feet).  The County also will require a larger setback if the ADU is taller than 15 feet (note that the Town does not allow accessory buildings to be taller than 15 feet).
  • The County’s lot coverage rules will apply to detached ADUs.
  • There will be no screening requirements for detached ADUs, though if the ADU is closer to the side property line than a house is allowed to be, no new windows could be put in the wall on that side.

Will ADUs have an impact on schools?
If the ZTA encourages larger, family-sized ADUs, it is possible that there will be an increase in the number of students.  And although the owner of a newly built home must pay a school impact fee, a freestanding ADU for a family will generate no fees.

ADUs in the Town

What has the Town done so far?
The Town Council, assisted by the Land Use Committee, has kept up with each phase of ZTA 19-01’s progress.  Mayor Barney Rush testified for the Town at the Planning Board’s February 14 hearing and Council member Joel Rubin testified for the Town at the County Council’s February 26 public hearing. They conveyed the Town’s support for most of the ZTA’s provisions. 

The Town also expressed the position that size limits should be retained on ADUs and that existing accessory buildings converted to detached ADUs should not be exempt from setbacks.  Following the County Council’s June work session, the Town sent a letter expressing support for several of the changes made to the proposed ZTA arising from the work session review.   The letter specifically referenced our support for the following modifications to the initial draft ZTA: 1) retention, in most instances, of, the 1,200 square foot cap on the size of an ADU, and 2) retention of the requirement that, in most instances, an attached ADU must have a separate entrance at the side or the rear of the primary dwelling.  The Town again requested that existing accessory buildings converted to detached ADUS not be exempt from setbacks. Read the letter. The Town’s position on setbacks for detached ADUs should not prevent someone from having an ADU.  A resident interested in developing a non-conforming detached ADU could seek a variance, and, in any event, could build an attached ADU. The Town continues to solicit comments from residents.

Can the Town regulate ADUs in the Town?
The Town has the authority to regulate the setbacks, height, and mass of buildings in the Town, the amount of impervious surfaces, stormwater runoff, tree removal, and parking. The Town’s rules can be more restrictive, but not less restrictive than the County’s rules. Thus, the Town can regulate some aspects of an addition to a house used for an attached ADU and of an accessory building used for a detached ADU.

If the Town does not change its current rules for accessory buildings, what could happen with detached ADUs in the Town?

  • A detached garage built before May 31, 2012 could be converted to an ADU without regard to setbacks. Older garages often sit on or very close to the side and/or rear property lines. If the building does not meet the setbacks required for new ADUs, a new window could not be put in the side nearest the property line. The building’s footprint could not be enlarged or its height increased.
  • If a new building is constructed for a detached ADU it would have to:
    • Be located in the  rear yard and occupy no more than 25% of the rear yard;
    • Be located at least 12 feet from the rear property line;
    • Have at least the same side setbacks as currently required for a house;
    • Have a height of 12 feet or less if it has a flat roof or 15 feet or less for other roof types.  Its gross floor area would be limited by the County size limits (see above), by the County’s lot coverage rules, and by the Town’s Floor Area Ratio rules.

Would the Town’s stormwater regulations control stormwater runoff from a detached ADU?
Only if the footprint of a new detached ADU was 700 square feet or greater, or if construction on the lot requiring a stormwater plan took place within the prior 2 years.

Changing Town Rules to Govern ADUs
The Town can adopt rules to govern detached ADU setbacks, height, and screening, stormwater runoff, and impacts on the tree canopy. It can also adopt rules about parking requirements for attached and detached ADUs. But before considering any measures, we would like to hear views from residents on this matter. Please write to the Town Office if you have interest or questions.

Topics to Consider

  • Should the Town regulate the setbacks of a detached ADU located in an accessory building built before May 31, 2012?
  • Are the setbacks the County approved for detached ADUs built after May 30, 2012 adequate, or should the Town require more restrictive setbacks?
  • Should the Town require screening for a detached ADU?
  • Should the Town adopt regulations to control stormwater runoff from detached ADUs?
  • Should the Town adopt additional parking requirements for ADUs?

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