Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
Smart Growth / Smart Energy Toolkit
Accessory Dwelling Units Accessory Dwelling Units (ADU)(ADU)
Accessory Dwelling Units Accessory Dwelling Units (ADU)(ADU)
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
• An Accessory Dwelling Unit is a secondary housing unit on the same property as a main residence.
• ADUs are also called accessory apartments, in-law apartments, family apartments, or secondary units.
• ADUs are not duplexes :– Size of ADU is subsidiary to the main residence– Owner of ADU usually lives on the property
• ADUs are self-contained
What is an ADU?What is an ADU?
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
Why consider an ADU Why consider an ADU bylaw?bylaw?
• Shrinking household size
• Rising real estate costs
• Aging population
• Neighborhood stability
• Character of neighborhoods
• Environmental benefits
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
What does it do for you?What does it do for you?• Municipality:
– Increases tax revenue– Minimizes subsidies required for
affordable units– Maximizes use of existing infrastructure
and services– Keeps growing and aging families
together– Preserves existing homes and
historic structures– Promotes safe and stable neighborhoods
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
Who benefits from ADUs?Who benefits from ADUs?
• Homeowners – rental income
• Middle-income tenants – more units
• Local businesses – employee housing
• Real estate firms – rental stock
• Residential contractors – remodeling
• Lending institutions – home improvement loans
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
Affordable ADUsAffordable ADUs• Local Initiative Program can be an
instrument for affordability• ADU qualification conditions for MA
Subsidized Housing Inventory (SHI)– Unit approved by local bylaw and DHCD– Unit occupied by income-eligible tenant
(≤80% of area median income)– Unit rented at affordable price over term
of control
• For SHI details, contact Department of Housing and Community Development at www.mass.gov/dhcd
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
Who typically chooses to Who typically chooses to build ADUs?build ADUs?
• Older singles/couples
• Middle-aged "empty nesters"
• Younger singles/couples
• Single working parents
• People who travel often
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
• Apartments in single-family homes
• Additions to homes
• Conversion of garages or barns
• Free-standing cottages
• Designed into new construction
How and where are ADUs How and where are ADUs built?built?
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
ADUs and Neighborhood ADUs and Neighborhood TypeType
Traditional Neighborhood Blocks
Features:• Shallow lots, with or without
alley• Carriage houses and garages
at the back of the lot• Original carriage houses
small single bay buildings• ADUs sited along alley
frontage or rear property line
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
ADUs and Neighborhood ADUs and Neighborhood TypeType
Transitional Neighborhood Blocks
Features:• Pre-war grid blocks with pre-
and post war housing• Deep lots• Garages located in rear
yards• ADUs placed within garage
zone in rear yards
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
ADUs and Neighborhood ADUs and Neighborhood TypeType
Suburban Neighborhood Blocks
Features:• Cul-de-sac blocks• Small yards• Parking in front of lot with
20’ driveway parking• ADUs sited in rear lot
areas on bigger lots and/or garage conversions
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
ADU Option 1: Apartments ADU Option 1: Apartments within Single-Family Homeswithin Single-Family Homes
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
ADU Option 2: Additions to ADU Option 2: Additions to Single-Family HomesSingle-Family Homes
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
ADU Option 3: Conversion ADU Option 3: Conversion of Garages, Barns, of Garages, Barns,
OutbuildingsOutbuildings
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
ADU Option 4: Construction ADU Option 4: Construction of New Outbuildingsof New Outbuildings
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
ADU Option 5: Designed ADU Option 5: Designed into New Constructioninto New Construction
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
Regulation of ADUsRegulation of ADUs• Zoning ordinance/bylaw
– Specifies ADU conversion standards
• As-of-Right– For interior alterations
• Special Permit– For exterior changes and out buildings
• Licensing– Periodic appraisal of ADU via renewal
or for change in ownership
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
Summary of ADU Summary of ADU BenefitsBenefits
• Creates new housing using existing infrastructure and services
• Reduces energy consumption• Generates community dollars
through home equity• Reduces costs for the elderly• Preserves housing stock and
neighborhood stability
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
Selected MA Selected MA communities with ADU communities with ADU
bylawsbylaws• Case studies
– Pelham, rural community– Lexington, suburban community– Northampton, urban community
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
Additional InformationAdditional Information
• MA Housing Partnership (MHP)http://www.mhp.net
• MA Department of Housing and Community Development (DHCD)http://www.mass.gov/dhcd/
• Background on Subsidized Housing Inventoryhttp://www.mass.gov/dhcd
• Older Americans Act websitewww.aoa.dhhs.gov
Smart Growth / Smart Energy Toolkit Accessory Dwelling Units
Additional InformationAdditional Information• ‘Taking the Initiative – A Guidebook on Creating Local
Affordable Housing Strategies’, CHAPA and MHP, Chapter 3, pp. 49-51 (March 2003)http://www.mhp.net/uploads/resources/taking_the_initiative_guidebook__ch._111.pdf
• ‘Granny Flats Add Flexibility and Affordability’, New Urban News Ithaca, NY, New Urban Publications, (2001)http://www.newurbannews.com/accessory.html
• ‘Accessory Apartments’, Leo L. Cram, Missouri Gerontology Institute, University of Missouri (1993)http://muextension.missouri.edu/explore/aging/gg0014.htm
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