HomeMy WebLinkAboutADUStudyReportRALEIGH URBAN DESIGN CENTER
REPORT 02:
ACCESSORY DWELLING UNIT PROGRAMS AND REGULATORY TOOLS
FALL 2020
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Demonstration/Pilot Project
Multiple ADUs
Anti-Displacement Programs
Pre-Approved Plans
Setback Relief
Tiny Home Village
Affordability Bonus
Flag Lots
Annual ADU Monitoring
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Permitting, Processing and Design Assistance
Programs
Regulatory Tools
Raleigh Urban Design Center | 1 Exchange Plz, Raleigh, NC, 27601 | 919.996.4642
RALEIGH URBAN DESIGN CENTER
Charles Dillard, AICP, Urban Designer
Joe Michael, AIA Principal Urban Designer
Elizabeth Nooe, Associate AIA, Urban Designer
Lee Stevens, Urban Designer
ACCESSORY DWELLING UNIT PROGRAMS AND REGULATORY TOOLS
URBAN DESIGN REPORTPREFACE
The purpose of this study is to present research
into best practices in approaches to Accessory Dwelling
Units. The report provides a rationale for programs
and regulatory tools the City of Raleigh can employ
to facilitate construction of ADUs, particularly as
affordable housing.
Limits of Zoning Regulations
03 Introduction
Summer 2020
3
INTRODUCTION
Limits of Zoning Regulations
Raleigh’s experience with ADUs has mirrored that
of peer cities nationally. Particularly high demand
cities like Asheville, Portland and Los Angeles have
responded to the converging housing and climate
crises by quickly adopting standards to enable ADU
construction. Raleigh’s 2020 UDO revisions are a
significant regulatory step toward facilitating ADUs
However, flexible regulatory environments have not
been effective in inducing anticipated demand. It is
only through the application of programs, policies
and constant regulatory evolution that cities have
seen ADUs built in meaningful numbers and in ways
that help combat the extreme shortage of housing.
This document is a summary of best practices from
across the United States. The programs and regulatory
approaches presented here are intended as precedents
for future ADU approaches. Some of the tools are
intended simply to increase supply, while others are
meant to provide explicitly affordable housing.
Three cities - Portland, Seattle, and Los Angeles, have
seen the most significant and meaningful increase
in ADU construction. These cities are supported by
permissive state law, particularly Los Angeles, where
the State of California has created the nation’s most
pro-ADU state statutes in response to that state’s
housing crisis.
Even with programs and regulatory approaches that
favor ADUs, the units account for only approximately
two percent of new housing units in these three
cities.
A two percent share of new housing units would put
Raleigh among the nation’s cities with the highest
ADU uptake. With approximately 11,000 new housing
units created in the city annually, this would mean
over 200 ADUs could be constructed throughout the
city’s residential zoning districts each year.
While not always affordable, ADUs are typically rented
at or below market rate. Data from Portland shows
that 15 percent of ADU inhabitants pay no rent,
while in San Francisco, ADUs rent for 19 percent less
than market rate rental units. Additionally, programs
targeting affordability can provide guaranteed
affordable housing. With a need for more than 60,000
units of affordable housing in 2019, Wake County
has recommended ADUs as one tool in the effort to
increase housing affordability and security.
ADUs are likely to be a small part of Raleigh’s housing
solution. However, ADUs fill a particular niche in the
housing market, as detailed in this document. As such,
this document lays out near term recommendations
that can be accomplished within six months and
longer term strategies that can be explored as desired.
4
PROGRAMS
Permitting, Processing and Design Assistance
Definition:
A broad set of programs that seek to reduce
the cost and time commitment required to
construct ADUs. Approaches include reduced
or eliminated permitting fees, expedited
processing, design assistance and education.
Some municipalities have created “one-stop-
shops” or guidebooks that serve to educate
their communities about ADUs and the
rules regulating them, help them identify
opportunities for constructing ADUs on their
property, and assist with design and permitting
processes.
Rationale:
The nature of ADUs – small structures typically
located in the rear yard of properties, is suited
for small scale or novice developers. Guidebooks
and one-stop-shops can be critical in educating
communities, reducing risks, and building
ADUs in meaningful numbers and in ways that
strengthen neighborhoods and create a more
equitable city.
Where Practiced
• California applied new ADU rules in 2020, one
of which prohibits municipalities from charging
impact fees for ADUs under 750 square feet.
Impact fees for larger ADUs are mandated
to be proportional to the size of the ADU in
relation to the primary dwelling. Impact fees in
California
• San Francisco created sf-ADU, a guidebook
that “helps define the various physical forms
for ADUs; multiple City Codes which regulate
adding ADUs, and when such investment
is financially feasible or beneficial to small
property owners.” The guide includes typical
floor plans, traditional and novel ADU formats,
and pro forma examples.
• San Mateo County, CA established the Second
Unit Resources Center, a hub for information on
ADUs, local ordinances, and programs available
to facilitate their construction. The site includes
a calculator that allows prospective builders to
estimate project costs, anticipated rents and
expenses, and other financial considerations.
The County also established in 2019 a One Stop
Shop Program that provides up to 100 hours of
project management to help design, permit and
process ADUs.
Recommendations
>Create an ADU Resource Guide to educate
homeowners and the development
community (Near-Term)
Principles:
• Format guidebooks and one-stop-shops to be
engaging and easy to use
• Designate and train staff to coordinate and
administer ADU Resource Center
Equity Opportunities:
• Supports inexperienced ADU builders
• Explore partnership with NCSU.
For Further Consideration:
>Determine staff capacity
>Explore building permit and facility fee
reductions for ADUs (Medium-Term)
Principles:
• Eliminate fees for homeowners or where
affordability is guaranteed
• Prioritize financial assistance to disadvantaged
and lower-income developers
Equity Opportunities:
• Increased affordable housing stock
• Supports inexperienced ADU builders
• Lowers cost to entry
For Further Consideration:
• Determine impacts of reduction scenarios
5
looks like I can add a unit
to my lot! What’s Next?
1. collect initial information
2. design + permitting
3. construction
take photos of your lot
to capture angles that show the available space relative to existing structures.
Bring your information
to the pre-application process with the Dept. of Building & Safety.
Begin Preliminary Project Design andDetermine Financing
complete construction drawings
submit building permit application and pay fees
revise drawingsas required by city
building permit issued obtain bidsfrom contractors
select contractor
certificate of occupancy done! Your new unit is ready
construction inspections begin construction
make a sketch
of your existing house and yard, showing the location and dimensions of structures on your lot.
14 building an adu | citylab version 1.0 | Summer 2017 15
tips for Drawing your
existing lot
Sketching an adu on your
existing lot
Measure and draw the shape of your lot.
Make notes of measurements on the sketch in terms of feet and inches.
As precisely as you can, draw the outline of your current house with measurements.
Measure and draw other permanent structures where they exist on your lot, such as a garage. Mark the location of the driveway, major trees, and all structures (even if they will be demolished).
Make a copy of the drawing of your existing lot and sketch a floor plan of the ADU you want to build.
Show where you would park a car(s).Tip: a typical parking space is 8ft 6in x 18 ft
Show any streets and alleys adjoining your lot.
Measure and block out 5 feet from each property line (for the setbacks).
Remember to leave at least 10 feet between the main house and your ADU, and avoid placing any structure(s) in the side and rear setbacks.
7Homeowner Design Package The Backyard Homes Project
The Micro-Unit (2BR)$ 180,000 596 SF2 Bed, 1 Bath
The Micro-Unit plan focuses on creating the most efficient use of space -- fitting the most comfortable, functional, and beautiful spaces into the least amount of square footage. The Living, Dining, and Kitchen areas all open up to the patio, allowing them to feel much larger and connected to the outdoors. This version includes two bedrooms, along with a built-in desk in the living room and a built-in window table in the kitchen.
Exterior Styles
Starting at:
About the Home
ModernThis style is characterized by minimal, clean lines and simple forms. Pictured here is a Sawtooth roof.
SpanishThis style is inspired by traditional Spanish architecture. It typically features a covered outdoor patio with columns, along with archway openings.
CraftsmanThis style is inspired by the Craftsman homes found throughout LA, typically characterized by pitched roofs and wood detailing.
FLOOR PLANS
Homeowner Design
Package
LA Backyard Homes Project
Their Design Package provides
building plans and budgets to
meet a wide array of housing
needs. (LA Mas)
ADU Guidebook
City of LA/UCLA cityLAB
Following the 2017 passage of state laws around ADUs, the LA Dept. of
City Planning partnered with UCLA’s cityLAB to create this document
that is intended as a guide for ADU developers, up to 78 percent of
whom are homeowners. (accessorydwellings.org)
ADU Guidebook Mock-Up
Many Raleigh residents
have concerns about ADUs.
Many ADU developers are
unfamiliar with the process
of designing and building.
Even seasoned affordable
housing developers may
be unaware of programs
supporting ADUs. A helpful
and engaging guidebook
and website can be a tool
in building public trust and
understanding. The diagram
to the right is an example of
a narrative-based approach
that many cities have
adopted.
Blake, 32 Logan + Jesse, 51, 56 Frankie, 73
Municipal permitting process expedited through the City
Blake used a localdesign firm found throughthe City’s ADU Hub to make a custom ADUthat can be rented or an office space
Frankie sells his land to a Community LandTrust for the appraised value, but maintainsownership of his home ADU Hub
$ADU Partners
Logan + Jesse bought plans they found onlinethat fit their needs
Municipal permitting process expedited through the City
Gary,41
Because Gary wants to make his ADU
affordable for renters, the City will give him a construction loan
Gary plans to convert hisdetached garage into an ADU
Municipal permitting process expedited through the City and fees waived for the affordable unit
Logan + Jesse opt in to the financing pilot program to help secure low-interest funds
to build without risk of getting priced out of their neighborhood
Because Blake’s ADU is less than750 square feet, she isn’t charged any fees by the City typically associated with construction
$$$
The CLT uses pre-approved prototypeplans from the City’s HUB site to skipthe permitting process
As the land is next to a transit stop,the CLT is eligible to build an extra ADU on the land
1 2
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PROGRAMS
Demonstration/Pilot Project
Definition:
A time-limited program to develop one or
more ADUs, the primary purpose of which is
to demonstrate the feasibility and impacts
of ADUs. Demonstration projects can pilot
potential long-term design standards or equity
and affordability programs. Pilot programs can
also test tenure models (e.g. community land
trust) and financing products
Rationale:
Despite continued effort to facilitate ADU
development nationally, construction has not
occurred at the intended pace. Demonstration
projects can be valuable experiments for
communities interested in ADUs but unsure of
how to regulate, incentivize, or finance them.
Demonstration projects are frequently executed
collaboratively by government, non-profit and
private sector partnerships.
Where Practiced
• Los Angeles established a partnership between
city government, non-profits and private sector
firms to conduct a pilot project to design,
permit, and build a new, two bedroom, two
bathroom, 1,000 SF ADU within a historic
district and on a hillside lot. The intentionally
difficult program demonstrated how ADUs can
be contextually designed, what regulations,
policies and programs are needed, and how
ADUs can be financed.
• Los Angeles County’s ADU Pilot Program
has a goal of demonstrating how ADUs
can be a strategy to provide homes to the
currently unhoused. The program streamlines
the permitting process, provides technical
assistance to homeowners, and most
substantially, financial incentives for preserving
and constructing accessory dwelling units
in exchange for housing homeless families/
individuals.
• Multnomah County, Oregon conducted a pilot
program, A Place for You to experiment with
different ADU building models and permitting
approaches. Funding from local government
and charitable organizations ($500,000)
constructed four ADUs – two modular and
constructed off site and two constructed on
site using innovative technologies. Each of the
ADUs will be the home for at least five years
to a formerly unhoused individual or family.
Following the five year period, the property
owner has the option to purchase the unit at a
reduced price.
LA Pilot Program
City of Los Angeles and partners
Highland Park ADU created through the LA pilot
program. The program intentionally selected a
sloped site in a historic district to determine ADU
feasibility in difficult conditions. Promotional
material for the program is to the right. The
completed ADU is below. (Stephen Schauer)
7
Recommendations
>Study Pilot Program feasibility to test
programs and regulations (Long-Term)
Principles:
• Facilitate permitting and approvals process
• Partner with non-profits and private sector
• Monitor experience to inform ADU regulations,
policies and programs
Equity Opportunities:
• Program can require affordability
• Provides baseline ADU rental rate data to inform
future affordability programs
For Further Consideration:
• Engage potential participating neighborhoods
• Identify community, non-profit and private sector
partners
The programs recommended on the following
pages could be tested as demonstration projects.
Such projects provide valuable baseline data on
ADU rental rates, construction costs, and length
of approvals processes, as well as a greater
understanding of design standards. Well-monitored
demonstration projects can inform future programs,
policies and regulations.
8
PROGRAMS
Pre-Approved Plans
Definition:
Acknowledging the typically simple form and
construction type of ADUs, municipalities in
communities experiencing severe housing
shortages have pre-approved building plans to
reduce costs and ensure a quick and efficient
permitting process. Pre-approved ADU plans
can be provided free of charge or for a fee –
typically a relatively small royalty fee to the
ADU designer.
Rationale:
Pre-approved plans reduce costs and promote
quick and efficient permitting and construction.
This low-risk program type can facilitate
development for some prospective developers
who desire a more hands-off approach and/
or lack the willingness or ability to manage
a construction project. Raleigh’s strong local
design industry and NCSU’s Design School are
assets to consider in the creation of such a
program.
Where Practiced
• San Diego, through its Housing SD program,
accepts pre-approved ADU plans, in addition to
fee waivers, expedited processing, and design
standard relaxations.
• San Jose’s pre-approved plans include a pre-
fabricated modular unit.
• Seattle engaged its residents on design
principles and criteria and invited designers
and builders to submit plans. City staff selected
the plans, which are available to residents for
the price of a royalty to the designer.
Recommendation
>Create pre-approved ADU program
(Medium-Term)
Principles:
• Promote local designers and construction firms
• Ensure MWBE representation
• Pre-approve ADUs designed for accessibility
• Consider a range of design styles
Equity Opportunities:
• Supports local and MWBE firms
• Reduces cost and other barriers
• Reduces staff resources required to permit
housing units
For Further Consideration:
• Engage design industry in program development
9
Pre-approved DADUs
Seattle
Seattle has pre-approved 10 ADUs
and lists 153 others designs on
its page. Each of the pre-approved
designs is profiled, as shown to the
right. Many also offer detailed PDF
drawing and presentation sets that
include renderings and diagrams.
(City of Seattle)
Permit Ready ADU
(PRADU)
City of Encinitas
Residents can select from eight
pre-approved plans that allow for
customizing materials and door/
window placement. Applicants
must still acquire some permits to
construct. (City of Encinitas)
10
PROGRAMS
Affordability Bonus
Definition:
A bonus amount of additional square footage or
unit density. Typically, the bonus is granted in
exchange for affordability guarantees.
Rationale:
Affordability bonuses facilitate cost-efficient
affordable housing units. Bonuses can be
granted in exchange for a range of benefits,
including affordability and sustainability.
Where Practiced
• Portland – Residential Infill Project permits
an additional 0.1 bonus FAR when at least one
housing unit on a residentially-zoned property
is affordable to at least 80 percent AMI. To
promote neighborhood character preservation,
Portland also offers the same bonus when infill
units are added to a property whose existing
home’s façade remains.
• Austin – conducts the Affordability Unlocked
program, which waives or modifies some
development restrictions in exchange for
providing low- and moderate-income housing.
Bonuses include height and density increases,
parking and compatibility waivers, and
reductions in minimum lot sizes. While broad
in nature and not targeted specifically to ADUs,
the model could be uses to facilitate infill
development including ADUs.
• Seattle permits second ADUs only when
developers agree to rigorous green building
standards or commit to reserving the ADU for
affordable housing.
Recommendations
>Study feasibility or Affordable ADU Bonus
Program (Long-Term)
Principles:
• Consider bulk and additional unit bonuses
• Consider reduction in min. lot area standards
• Prioritize areas with demonstrated demand
Equity Opportunities:
• Encourages construction of affordable housing
For Further Consideration:
• Additional study needed to determine feasibility
• Determine areas appropriate for bonus
• Engage affordable housing developers and
advocates, in program creation
Affordability Bonuses
Seattle and Portland
These cities, among others, offer additional units or increased square footage standards when affordability
is guaranteed. FAR and permeable surface standards still apply. Similar bonus programs exist to incentivize
retention of existing built character and sustainable building practices.
11
Seattle and Portland Affordability Bonuses typically permit one
additional ADU in exchange for affordability guarantees
12
PROGRAMS
Anti-Displacement Programs
Definition:
ADUs can be an effective tool in fighting
displacement of renters and homeowners.
Some programs are tailored to fixed-
income homeowners in rapidly appreciating
neighborhoods to help them remain physically
rooted to their communities. Others are
structured to promote aging-in-place.
Rationale:
Housing shortages create instability in
neighborhoods. Homeowners on fixed or low
incomes in rapidly appreciating neighborhoods
are impacted heavily by rising tax rates. Older
residents also may find their existing home
inaccessible and desire a newly-built ADU that
is designed to be accessible. A program aimed
at fighting displacement, particularly in rapidly
appreciating areas of Raleigh, can be part of the
city’s effort to ameliorate and prevent structural
racism in the housing market.
Where Practiced
• Seattle’s Home Repair Program (similar to
Raleigh’s Homeowner Rehabilitation Program)
is piloting low-interest financing to homeowners
at risk of displacement. The value of the
property is leveraged without having to sell,
while the homeowner also avoids assuming high
levels of risk or debt.
• Santa Cruz County administers the My House
My Home program in partnership with Habitat
for Humanity. The county provides low, simple
interest financing to help low-income senior
homeowners build ADUs on their property.
The loans are deferrable for up to 30 years
or payable upon sale or transfer. In exchange,
the owners agree to rent the ADU – or their
primary home – to households earning at or
below 60 percent of the area median income.
• Los Angeles is monitoring a three-year pilot
program, the LA ADU Accelerator Program
to identify housing opportunities for older
adults facing housing insecurity. The city
screens ADU owners and renters to ensure an
easy and efficient experience. In exchange for
participating, homeowners receive guaranteed
timely rent and landlord support.
Recommendations
>Explore creation of Anti-Displacement
Program (Long-Term)
Principles:
• Partner with non-profit housing providers
• Provide financing - loans, grants, underwriting
• Prioritize community ownership models (CLTs)
• Prioritize areas with significant displacement
• Pair with bulk and additional unit bonuses
Equity Opportunities:
• Encourages construction of affordable housing
• Helps residents stay in their communities
For Further Consideration:
• Additional study needed to determine feasibility
>Explore loan program to assist
homeowners at risk of displacement with
ADU construction (Long-Term)
Principles:
• Provide low-cost loans for ADU construction or
conversion
• Require affordable rental rates
• Explore use of Homeowner Rehabilitation
Program funds
Equity Opportunities:
• Encourages construction of affordable housing
• Helps residents stay in their communities
For Further Consideration:
• Additional study needed to determine feasibility
Retired homeowners on fixed income faced with rising property taxes and
upkeep in a gentrifying neighborhood.
Owners recieve assistance to build ADU or sell land to CLT, providing rental
income or an infusion of cash. They can remain in their home.
ADU provides new
affordable home.
Anti-Displacement Programs
Seattle, Santa Cruz, CA
These pilot programs provide low risk ADU financing to homeowners at risk of displacement. Some owners
decide to rent out the ADU, others live in the ADU and rent the primary home at an affordable rate. Such
programs can also be used by Community Land Trusts to preserve and create perpetually affordable housing.
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PROGRAMS
Tiny Home Village
Definition:
A small collection of tiny homes, typically
arranged in a village format along with services
and open spaces, that provides short- and
medium-term housing for the unhoused.
Rationale:
The population of unhoused residents is
growing. Tiny home villages can provide short-
to medium-term housing for the unhoused. Site
selection should ensure that residents are not
isolated and can access services and participate
in their communities. Tiny Home Villages are
the emergency shelter most effective in limiting
the spread of COVID-19.
Where Practiced
• Seattle partners with the Low Income Housing
Institute to construct tiny home villages in
response to the city’s homelessness crisis. The
10 villages are located throughout the city on
government, private, non-profit and church-
owned properties. Sites range from 6,000
square feet to 30,000 square feet. In 2018,
Seattle’s villages served nearly 900 unhoused
individuals, with village operating costs ranging
from $60,000 to $500,000.
• Austin is home to Community First, a 27-acre
tiny home village of 180 200-square foot homes
and on-site employment opportunities. The
village was constructed with $18 million in
charitable donations.
• Bernalillo County (Albuquerque) is creating
a $4.34 million tiny home village. The village
contains a “community house” with bathrooms,
kitchen and common space and a wraparound
porch. The County’s goals are to provide “safe,
stable, and attractive” transition housing in a
holistic neighborhood where residents can work
and access services. The one-acre site hosts 30
124 square foot homes. The ultimate cost of
the project was $4.34 million.
Recommendations
>Explore partnership with non-profit sector
to construct Tiny Home Village program
(Long-Term)
Principles:
• Locate close to services and amenities
• City in funding role
• Foster collaboration between public, private and
non-profit sectors
Equity Opportunities:
• Housing for the unsheltered
• Emergency housing for NC communities
displaced by climate change
For Further Consideration:
• Additional study needed to determine feasibility
Bernalillo Co. Tiny Home Village
Albuquerque
The village’s plan includes a “Village House” at its
center to provide the community an on-site location
for service provision. The village also includes
gardens and detailed landscape design.
Seattle Tiny Home Village
City of Seattle/Low Income Housing Institute
Tiny Home Village, Seattle, WA. Seattle’s Low
Income Housing Institute, with City of Seattle
financial backing, has created 10 tiny home villages,
housing hundreds of previously unsheltered
households. (wbur.org)
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VILLAGE HOUSE2,515 SF
GARDEN
FENCE AROUNDPERIMETERPROPERTY LINE
PROPERTY LINE
FENCE AROUNDPERIMETER
PROPERTY LINE SECURITY FENCE (E) CURB CUT(E) SIDE WALK
WRAP AROUND PORCH
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(TO REMAIN) 7,660 SF
DUMPSTERENCLOSURE
MOTORIZEDVEHICULAR GATE
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OUTDOORPATIO
SHADESTRUCTURE
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6' WIDE LANDSCAPE BUFFER AT PERIMETER
6' WIDE LANDSCAPE BUFFERAT PERIMETER
DONATIONS DROP-OFF
(E) PARKING LOT
ASPHALT PARKING7 SPACES
VACANT LOT
CRUSHER FINE PATH
LAWN
CLOTHESLINE
CISTERN
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(E) CURB CUT(E) CURB CUT(E) CURB CUTFUTURE DONATION STORAGE CONTAINER LOCATIONS
EXISTING ASPHALT, TO REMAIN
TOOL SHED
GUARDSHACK
TOOL SHED
(E) CURB CUT TO BE CLOSED.INFILL SIDEWALK FLUSH WITH ADJ.FLATWORK
AS-5011
/A1AS-501
A-106B3
16
PROGRAMS
Annual ADU Monitoring
Definition:
The general prohibition of ADUs across the
country contributes to a lack of knowledge
regarding their impacts as well as their role
within the housing market and physical
environment. Some cities are instituting
rigorous monitoring programs to better
understand ADUs, their impacts and their
role in providing needed density and greater
affordability.
Rationale:
The city currently monitors a range of
programs and services. Monitoring and annually
reporting on ADU development, the units’
role in the housing market, and their impact
on the environment and communities allows
for a measured introduction of ADUs into
neighborhoods while facilitating their role in
reducing the shortage of housing, particularly
affordable units.
Where Practiced
• Seattle, through a mayoral executive order,
initiated in 2019 an annual reporting process
to monitor ADU build-out. City staff track ADU
use, rental rates, affordability, parking, and
impact on the city’s open space, tree canopy
and economy. The goal of the reporting is
to allow for continual evolution of the city’s
approach to ADUs.
Recommendations
>Create ADU monitoring program
(Near-Term)
Principles:
• Monitor number, location and uses of ADUs
• Monitor rental rates and contribution to
affordable housing supply
• Monitor parking usage and provision
• Monitor impacts to green space and tree canopy
• Monitor impacts to stormwater infrastructure
Equity Opportunities:
• Improved understanding of ADU contribution to
housing supply and cost
• Improved understanding of ADU use
17
Duplex ADU, Healdsburg, CA. A renovation of two exisitng ADUs and one primary home. Jim Heild and Daniel Parolek
18
REGULATORY TOOLS
Multiple ADUs
Definition:
A rule permitting multiple Accessory Dwelling
Units on one property.
Rationale:
Permitting multiple ADUs on a lot allows for
much-needed densification at a scale consistent
with neighborhoods. However, such a rule is
best administered within the framework of
a Land/DU and/or Floor Area Ratio approach
and is most appropriately applied only in areas
close to high intensity urban centers and areas
with demonstrated demand for greater unit
density. It is also recommended that multiple-
ADU developments should only be permitted as
an incentive in the development of affordable
housing.
Where Practiced
• Portland uses a Land/DU + FAR approach that
creates a flexible development environment.
The approach permits a homeowner or
developer to allocate units in various forms
and combinations. For example, a property
owner in Portland’s R7 district (analogous to
Raleigh’s R-6) with a minimum 5,000 SF lot can
construct either a triples, a duplex with one
ADU, or a single family house with two ADUs.
• California state law (AB 68) requires that
municipalities permit up to two ADUs on
residential properties with zoning that permits
multifamily dwellings (i.e. Missing Middle).
Some municipalities permit two detached
ADUs.
• Seattle, like California, permits one attached
and one detached ADU on each residential lot.
Recommendation
>Explore UDO revisions to permit multiple
ADUs in TOD-R and other high demand
areas (Long-Term)
Principles:
• A Land/DU approach is most flexible
• Apply citywide or in targeted areas with
demonstrated demand
• Permit additional ADUs in affordability programs
Equity Opportunities:
• Increases supply
• More affordable housing in high-demand areas
For Further Consideration:
• Engage public on density standards and Missing
Middle Housing
ADU Court (4 Units)
Duplex ADU (2 Units)
Multiple ADUs
Portland, California, others
Portland and California now
permit two ADUs on a lot. Many
cities are permitting duplexes,
triplexes and quads in residential
districts. While multiple ADU
developments should only be
permitted after rigorous study and
outreach, Raleigh’s relatively large
lot sizes offer opportunities for
multiple ADU formats that do not
exist in denser cities with smaller
lots. Multiple unit formats can
also be paired with affordability
programs.
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Traditional ADU
3rd Unit
Multi-Unit ADU
(4-8 Units)
Zero Lot Line
or
Duplex ADUs
ADU Row
(4-8 Units)
Fee Simple
Duplex +
ADU (2 Units)
Duplex
ADU
Flag Lot
Condominium
Duplex +
ADU (2 Units)
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REGULATORY TOOLS
Setback Relief
Definition:
Many cities permit relief from side and rear
setbacks in their densest residential-only zoning
districts to allow zero lot line homes. Primary
and accessory dwellings in Raleigh’s oldest
neighborhoods were commonly built up to the
property line. Rigorous design standards are
necessary to mitigate impacts to neighboring
properties.
Rationale:
Zero lot line homes are a common reality in
Raleigh today. Exemptions from side and rear
setbacks in R-10 and TOD-R-mapped are
encouraged, but only according to rigorous
building and landscape design standards.
Where Practiced
• Portland permits structures in the setbacks
in their three densest residential districts -
roughly corresponding with Raleigh’s R-6 and
R-10 districts. Design standards ensure minimal
impact to neighboring property owners.
• Austin, through its Affordability Unlocked
Program, permits a reduction in front and
rear setbacks by 50 percent in exchange for
affordability.
Recommendation
>Explore revising UDO setback standards
to permit limited exemptions for ADUs in
high-demand areas (Medium-Term)
Principles:
• Establish maximum encroachment length
• Develop rigorous design standards to mitigate
impacts to neighboring properties
Equity Opportunities:
• Reduces barrier to housing construction
For Further Consideration:
• Further study needed to determine feasibility
and extent of setback exemptions
• Engage public on setback exemptions as part of
Missing Middle housing outreach
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Boylan Heights garage within the side setback - existing non-conformity. Permitting new
ADUs with similar scale and relationship to context would not be permitted today. Google
Saunders Street existing non-conforming homes. When built according to rigorous urban design standards, homes can be placed closely together while retaining privacy and desirability. Google
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REGULATORY TOOLS
Flag Lots
Definition:
A parcel behind one or more parcels that
maintains access to a public street via a long
narrow access way, typically a driveway. A
flag Lot home is not technically an ADU, but
typically is similar in form and scale. As such,
flag lots can be a strategy to finance or sell
ADUs.
Where Practiced
• Broadly applied
• Durham, in its Expanding Housing Choices
initiative, relaxed standards for flag lots
in recognition of their role in facilitating
development of infill housing with traditional
mortgage products.
Recommendation
>Explore revising UDO to permit Flag Lots
(Long-Term)
Principles:
• Permit larger unit sizes on flag lots
• Permit reduced pole width in areas with
demonstrated demand for greater unit density
Equity Opportunities:
• Facilitates traditional mortgage products for
ADUs
• Affordable Ownership Opportunity
For Further Consideration:
• Engage public on desirability of flag lots
• Continue study as part of Missing Middle housing
reform
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Flag Lots can allow for flexible subdivision of existing ADUs or to create land parcels that are well understood
by the financial sector and for which traditional mortgage products exist. hawaiiadu.org
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SUMMARY
Recommendations
Near-Term Strategies (6 Months)
Medium-Term Strategies (1-2 Years)
Long-Term Strategies (2 or more years)
This document provides a broad understanding of
effective best practices in use nationally. ADUs are a
small but necessary component of any city’s housing
strategy. These units are often an ideal option for
homeowners at risk of displacement - whether they
live in the ADU or in their current home. They are
ideal for those who desire to “age in place” - they
offer smaller, more accessible footprints in familiar
neighborhoods. They are ideal for those who require
additional care or temporary housing.
The broad range of recommended tools provided
in this document could facilitate more equitable
development in Raleigh’s neighborhoods, frequently at
a scale consistent with built context.
As stated in this report, many of the recommendations
require additional study to craft specific programs or
regulatory approaches.
>Create an ADU Resource Guide to
educate homeowners and the devel-
opment community
>Create ADU monitoring program
>Create Pre-Approved ADU Program
>Explore building permit and facility
fee reductions for ADUs
>Study feasibility of Pilot Program to test
ADU design typologies
>Study feasibility of Affordable ADU Bonus
Program
>Explore creation of Anti-Displacement
Program
>Explore loan program to assist homeowners
at risk of displacement with ADU
construction
>Explore partnership with non-profit sector
to construct Tiny Home Village program
>Explore UDO revisions to permit multiple
ADUs in TOD-R and other high-demand
areas
>Explore revising UDO setback standards to
permit limited exemptions for ADUs in high-
demand areas
>Explore revising UDO to permit Flag Lots
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