2019-04-24 (HPB Staff Report)To: Chair Foulkes and Board Members Date: April 24, 2019
From: Daniel Fama, Senior Planner
Subject: ADU Standards for HRI Properties
Background: Accessory Dwelling Units (ADUs) are small living units ancillary to a
single-family home, colloquially known as "granny-flats," "mother-in-law-apartments,"
"in-law units," etc. There are three types of ADUs: (1) "Attached," which are constructed
as a physical expansion (i.e., addition) to the primary house; (2) "detached," which are
constructed as a separate structure from the primary house; and (3) "interior" which are created using the existing floor area of the primary house, as illustrated below:
Detached Attatched Interior
A key feature of State law as it pertains to construction of ADUs is that they cannot be subject to any form of discretionary planning review, such as a Historic Resource
Alteration Permit or Site and Architectural Review Permit, which is how the City typically
oversees architectural design. This means that the City's ability to control the design of
an ADU or its integration with a primary home is significantly diminished compared to
non-ADU structures and additions.
The City is currently in process of updating its ADU ordinance to reflect recent State
legislation and to generally relax the existing standards to promote the creation of
additional housing in the community. The Planning Commission held study sessions at
its March 12th and March 26th meetings to discuss potential changes to the ordinance (reference Attachment 1 – PC Staff Report). By the end of the second meeting, a
majority of the Commission came to a consensus on new standards that will be
recommended to the City Council as summarized in Attachment 2.
Based on the Planning Commission's direction, staff will be drafting a new ADU
ordinance. As part of this process, it would be advantageous to develop specific standards for construction of ADUs on HRI-listed properties in order to protect their
historic integrity. Although the Board does not have a formal role in preparation of the
draft ADU ordinance, staff is requesting the Board's input to develop these standards in
order to aid the Planning Commission's deliberation.
City of Campbell MEMORANDUM
Planning Division
ITEM NO. 3
Staff Memorandum ~ HPB Meeting of April 24, 2019 Page 2 of 3 ADU Standards for HRI Properties
Discussion: Based on a Listserv inquiry to other cities, staff has created a summary table of the various standards and requirements for historic properties developed by the
cities of Benicia, Pasadena, Glendale, Santa Barbara, and Santa Rosa (reference
Attachment 3). Based on this research, the following (non-mutually exclusive) options
may be considered. If individual Board Members have additional ideas, those may also
be shared at the meeting.
Prohibit ADUs on Structures of Merit, Landmark and/or District Properties:
This would be the most restrictive approach for governing ADUs on historic
properties, one which staff would recommend against. However, if the Board
feels strongly about this option, that preference may be communicated to the
Planning Commission (although it would unlikely be incorporated into the draftordinance).
o A softer version of this option would be to prohibit "attached" ADUs due to
the risk of diminishing the historic integrity of the historic home. This would
still allow homeowner to construct "detached" and "interior" ADUs.
Special Development Standards: A separate set of development standardscould be developed for HRI properties:
o Placement: The Commission's consensus would allow "detached" ADUs
to be placed in front of, to the side, or to the rear of the primary house. For
HRI properties, placement could be restricted to the rear of the primary
home (or be required not to be visible from the public right-of-way) so thatthe ADU would not disrupt the appearance of the historic home.
o Second-Story "Attached" ADU: "Attached" ADUs could be restricted to the
first-floor so as to prohibit second-story ADUs atop of a historic home. As
noted above, without the standard permitting tools, it would be very
difficult to ensure that a second-story addition complies with the Secretaryof the Interior Standards and/or the City's Historic Design Guidelines.
o "Attached" ADU Placement: "Attached" ADUs could also be restricted to
the rear of the home so that they would not change the outward
appearance of the historic home.
o 2-Story ADUs: The Commission's recommendation would allow a"detached" ADU placed atop of a detached garage on a property with a
two-story home. This allowance could result in a two-story structure being
visible from the street, again disrupting the appearance of the historic
home, which may warrant a prohibition for HRI properties.
o Maximum Size: "Detached" ADUs could be up to the State maximum of1,200 square-feet, subject to the applicable development standards (e.g.,
FAR/Lot Coverage). Although the Planning Commission did not feel it
necessary to constrain the size of an ADU, it might be warranted to ensure
that on a historic property that an ADU does not exceed the size of the
primary home (which tend to be smaller than contemporary homes).
Staff Memorandum ~ HPB Meeting of April 24, 2019 Page 3 of 3 ADU Standards for HRI Properties
Special Design Standards: Although the Planning Commission's consensuswould require design consistency with the primary house for "detached" ADUs in
certain circumstances, more specific design standards could be developed for
HRI properties to provide for a greater degree of design consistency (as the City
of Benicia has done).
Zoning Exception: The Historic Preservation Ordinances provides for a type ofVariance called a "Zoning Exception" to allow flexibility to design standards. This
section could be amended to make specific reference to construction of ADUs. If
the City does adopt stricter standards for HRI properties, a "Zoning Exception"
could provide case-by-case flexibility.
Attachments: 1.Planning Commission Staff Report, dated March 12, 2019
2.ADU Recommendation Summary
3.Historic ADU Summary Table
To: Chair Hernandez and Planning Commissioners Date: March 12, 2019
From: Daniel Fama, Senior Planner
Via: Paul Kermoyan, Community Development Director
Subject: Accessory Dwelling Unit (ADU) Ordinance Update (PLN2017-375)
Planning Commission Study Session
BACKGROUND
Accessory dwelling units (ADU)—previously termed secondary dwelling units—have been allowed since the 1982 adoption of the Mello Act. The current regulatory environment was established with the passage Senate Bill (SB) 1069 and Assembly Bill (AB) 2299 in 2016. This
legislative package required local jurisdictions to adopt new ADU provisions to ease parking
requirements, increase unit sizes, remove fire sprinkler requirements, and simplify garage
conversions. The City Council adopted Ordinance No. 2216 on December 16, 2016 to incorporate new Chapter 21.23 (Accessory Dwelling Units) consistent with State law.
A second round of legislation (SB 229 and AB 494) was signed into law in October 2017 that
clarified and further eased requirements for construction of ADUs, specifically:
•Clarifies an ADU can be created through the conversion of a garage, carport or coveredparking structure.
•Requires special districts and water corporations to charge a proportional fee scale based
upon the ADUs size or its number of plumbing fixtures.
•Requires ADUs be allowed in any zoning district where a single-family residence is
permitted.
•Reduces the maximum number of parking spaces for an ADU to one space.
•Allows replacement parking spaces to be located in any configuration, as a result, of a
parking structure conversion to an ADU.
•Authorizes the Department of Housing and Community Development to review and
comment on ADU ordinances.
•Defines the term "tandem parking" to mean two or more automobiles.
In response to this legislation, as well as an October 17, 2017 City Council appeal hearing
pertaining to a proposed "garage conversion", staff was directed to prepare an ordinance update
to make the necessary revisions. A narrowly tailored ordinance update was presented to the
Planning Commission on February 15, 2018. Many residents offered testimony regarding the
need to reduce the minimum lot size (which is not a State mandate). Some felt it should be reduced to 8,000 square-feet while others felt it should be reduced even lower. The Commission
asked staff to research the ADU policies of other area cities so they could understand how
neighboring communities addressed this issue.
MEMORANDUM
Community Development Department
Planning Division
Attachment 1
Planning Commission Study Session – March 12, 2019 Page 2
PLN2017-375 ~ Accessory Dwelling Units.
However, the Council requested that this matter be agenized for a public discussion so that specific direction could be provided to the Planning Commission on the minimum lot size requirement. The study session was held on June 5, 2018, wherein the Council provided
guidance that the 10,000 square-foot minimum lot size was too high, with some Council
Members commenting that no minimum should considered. The Council also asked to look at
other variables such as unit size and open space. Nevertheless, no specific direction was provided leaving staff with the responsibility of researching how best to address the most appropriate minimum lot size.
Following the Council meeting staff prepared a comprehensive rewrite of the ADU ordinance that was presented to the Planning Commission on November 27, 2018 (reference Attachment 1
–Staff Report). In response to public comment and Commission questions at the meeting, the
public hearing was continued so that staff could conduct research on various development
standards (e.g., setbacks, 2nd-story ADUs, etc.), an alternate affordable housing incentive, and
Junior ADUs. Staff indicated that a study session would be scheduled so that the Commission may form a consensus on standards and requirements to be incorporated into a revised ordinance.
Since that time, staff continues to process permit submittals for ADUs. In the last year, a dozen
applications were submitted, and since the beginning of this year, an additional seven
applications were received.
DISCUSSION
The following discussion provides a comprehensive overview of the potential standards and
restrictions that may be applied to construction of ADUs, as well as a discussion on a below-
market-rate (BMR) incentive, Junior ADU options, and potential creation of a broader ADU development policy.
Development Standards
Minimum Lot Size: At its June 5, 2018 study session, the Council indicated that the current 10,000 square-foot lot size is too high and was willing to reduce it and possibly eliminate it so long as there were "other controls" in place, such as Floor Area Ration (FAR), Lot Coverage,
Minimum Open Space, etc.
Options Descriptions
Option 1
No Minimum Lot Size
Simple elimination of the minimum lot size, as previously recommended by staff, would maximize the number of properties eligible to construct an ADU
Option 2
6,000 Square-
Foot Minimum Lot Size
If the Commission believes eliminating the minimum lot size is too permissive, establishment of a 6,000 square-foot minimum lot size could be
considered. This would create consistency with the City's residential zoning
districts, none of which have a minimum lot size of less than 6,000 square-
feet.
Staff Note: The disadvantage of this option would be similar to the current 10,000 square-foot minimum lot size. There will always be properties that do
not quite satisfy the minimum lot size, the owners of which inevitably will
claim to be disenfranchised.
Planning Commission Study Session – March 12, 2019 Page 3
PLN2017-375 ~ Accessory Dwelling Units.
Maximum ADU Size: State law allows ADUs to be constructed up to 1,200 square-feet or 50% of the primary dwelling's living area if attached or interior, whichever is less. The City's current
standards comply with this limitation by tying the size of the ADU to the lot area as shown
below:
Lot Area (Sq. Ft.) Maximum Size (Sq. Ft.)
10,000-10,999 700
11,000-11,999 800
12,000-12,999 900
13,000-13,999 1,000
14,000-14,999 1,100
15,000 or greater 1,200
However, with the elimination or reduction of the minimum lot size, the Commission must
consider whether the size of the ADU should continue to be tied to lot area in some manner, be
limited by some other metric, or simply be controlled by the development standards of the
zoning district:
Options Descriptions
Option 1(a)
Tiered by Lot
Size
If the Commission wishes to generally maintain the existing size limitation,
the current tiering could be expanded by including an additional tier that
would allow lots under 10,000 square-feet to have an ADU of no greater than 600 square-feet:
Lot Area (Sq. Ft.) Maximum Size (Sq. Ft.)
>10,000 600
10,000-10,999 700
11,000-11,999 800
12,000-12,999 900
13,000-13,999 1,000
14,000-14,999 1,100
15,000 or greater 1,200
Option 1(b) Tiered by Lot
Size
The Commission could also establish a new tiering structure if the 15,000
square-foot top tier is deemed too high. For instance, the following table
would allow a maximum sized ADU (1,200 square-feet) on a 12,000 square-
foot lot and tier downward:
Lot Area (Sq. Ft.) Maximum Size (Sq. Ft.)
> 6,000 500
6,000-6,999 600
7,000-7,999 700
8,000-8,999 800
9,000-9,999 900
10,000-10,999 1,000
11,000-11,999 1,100
12,000 or greater 1,200
Planning Commission Study Session – March 12, 2019 Page 4
PLN2017-375 ~ Accessory Dwelling Units.
Options Descriptions
Staff Note: This option could also incorporate a smaller maximum size than
1,200 square-feet. For example, San Jose's top tier is 900 square-feet for lots
larger than 10,000 square-feet.
Option 2 State Maximum
Allow an ADU up to the State maximum of 1,200 square-feet, as may be
limited by the applicable Floor Area Ratio (FAR), lot coverage, and open
space requirements of the property's zoning district, irrespective of lot area.
Staff Note: Certain P-D (Planned Development) zoned properties in the South Downtown neighborhood do not have specific development standards,
which would effectively allow a maximum sized ADU (1,200 square feet)
irrespective of how large the primary dwelling is and/or whether other
structures exist on the property, such as a detached garage, unless specific
restrictions were established.
Option 3 Local Maximum
Similar to Option 2 (State Maximum), the City could establish its own local
maximum size irrespective of lot area. For example, Mountain View and Sunnyvale have a maximum size of 700 square-feet.
Staff Note: This option would be a return to the format that previously
existed prior to 2016 when the City imposed a flat maximum size of 640
square-feet.
Option 4
Proportional to Lot Area
Restrict the size of the ADU relative to the size of the lot. For instance,
Cupertino specifies the maximum size shall be no greater than 10% of the lot
area. Such an approach maintains a relationship between lot area and ADU
size, similar to Option 1 (Tiered Approach), but at a more granular scale.
Staff Note: Because the size of an ADU would be so closely linked to lot area, staff would likely have to require boundary surveys for many properties
to verify the exact lot size to determine the allowable ADU size, at the
homeowner's expense.
Option 5 Proportional to
Primary
Dwelling
Limit the size to the percentage of the primary dwelling's living area. For
instance, San Mateo County limits the maximum size to 750 square-feet or
35% of the primary dwelling's existing or proposed living area, whichever is
larger, up to a maximum of 1,200 square-feet (requiring a 3,428 square-foot primary dwelling to maximize the size of the ADU).
Staff Note: Similar to Option 4 (Proportional to Lot Area), staff would likely
need to require measured floor plans of the primary dwelling to verify the
existing size to determine the allowable ADU size, at the homeowner's
expense. This option may also be seen as unfair to homeowners with smaller homes who would be disadvantaged.
Primary Dwelling Type: Currently and as previously recommended by staff, the ability to construct an ADU would be limited to residential properties developed with a single detached
single-family dwelling as the property's "primary dwelling". However, if the Commission wished
to expand the ability to create an ADU, the definition of "primary dwelling" could be broadened,
as noted below:
Planning Commission Study Session – March 12, 2019 Page 5
PLN2017-375 ~ Accessory Dwelling Units.
Options Descriptions
Option 1 Detached Single-
Family
As noted, only properties with a single detached single-family dwelling could
construct an ADU, excluding P-D (Planned Development) properties that
have already been developed with more than one primary dwelling unit.
Option 2
Detached Single-Family and Townhomes
In addition to single-family dwellings, attached townhome dwellings could
also be afforded the ability to create an interior ADU (i.e., due to lot size and
physical limitations such ADUs would need to be created from the existing
rooms).
Staff Note: Since all townhome developments are governed by CC&R
documents, the ability to create an interior ADU would be contingent on
securing Homeowner's Association (HOA) approval. State law does not
prohibit any such private restrictions from being enforced.
Setbacks: Another key consideration has been the establishment of new setback standards for
ADUs. Historically, the City has required that ADUs comply with the setback standards applicable to the primary dwelling. However, this has created a significant burden in the San Tomas Area due to the 20- to 25-foot rear setback and 8- to 10-foot side setback requirements
established by the San Tomas Area Neighborhood Plan. For this reason, staff had previously
recommended establishment of uniform setbacks for detached ADUs based on those adopted in
Campbell Village Area Neighborhood Plan. In addition to reducing an existing constraint, it would also simplify the regulation of ADUs by creating City-wide uniformity.
However, some residents expressed concern that the recommended standards were still too
burdensome. The following table provides a comparison between current standards, the previous
recommended standards, and a more permissive alternate option based in part on community feedback. Note that more permissive setbacks would not apply to the properties subject to the Campbell Village Area Neighborhood Plan, which incorporates its own standards that would
supersede those adopted by a new ADU ordinance. The City Council would need to authorize an
Amendment to the Neighborhood Plan to create City-wide uniformity, which they have not done.
Development
Standard Current Standards Previous Staff
Recommendation
Alternate (Permissive)
Option
Setbacks
Front
The same standard as for the primary dwelling
The same standard as for the primary dwelling
Rear 10 feet 5 feet
Interior Sides 5 feet 5 feet
Street Side 12 feet 5 feet
Building Separation
Behind Distance equal to
building wall height of
the taller of the two
structures
10 feet 5 feet
Side 5 feet 5 feet
Planning Commission Study Session – March 12, 2019 Page 6
PLN2017-375 ~ Accessory Dwelling Units.
As requested by the Planning Commission, staff prepared various "fit plans" illustrating potential differences between the previous staff recommendation and the alternate option with regard to setbacks and building separation requirements. The fit plans are presented in four scenarios for
"typical" properties found in the San Tomas Area (which would see the most significant
changes) developed with average-sized homes. Two scenarios assume R-1-6 zoned, 6,000
square-foot lots (100-ft x 60-ft) and two others R-1-10 zoned, 10,000 square-foot lots (125-ft x 80-ft), with either attached or detached garages:
Scenario 1 – 6,000 SQ FT Lot w/ Attached Garage (reference Attachment 2)
Scenario 2 – 6,000 SQ FT Lot w/ Detached Garage (reference Attachment 3)
Scenario 3 – 10,000 SQ FT Lot w/ Attached Garage (reference Attachment 4)
Scenario 4 – 10,000 SQ FT Lot w/ Detached Garage (reference Attachment 5)
The fit plans reveal that for the 10,000 square-foot lots, either the previous staff recommendation
or the alternate option would allow a maximum sized ADU of up 1,200 square-feet with an
attached garage while maintaining consistency with the applicable FAR, lot coverage, and open space requirements. In other words, simply due to the size of a 10,000 square-foot lot, either set of standards would allow maximization of development, in both the attached or detached garage
scenarios.
However, on smaller 6,000 square-foot lots the effect of the lesser lot area is more pronounced than that of the development standards. For instance, the largest ADU that could reasonably be constructed on a property with a primary dwelling with an attached garage is approximately 800
square-feet simply due to the FAR and Lot Coverage requirements. Similarly, on properties with
detached garages, the need to maintain the minimum amount of open space (750 square-feet)
further reduces the effective maximum size of an ADU to approximately 500 square-feet.
Ultimately, the fit plan exercise demonstrates that the previous staff recommendations would not
create an undue burden on development ADUs, although the alternate standards would provide
greater flexibility in terms of ADU placement and configuration. However, a rear setback of 10-
feet may provide more a functional rear yard/patio area for the ADU than a 5-foot setback and also provide a greater sense of privacy for abutting properties. This option is contrary to public comment that contended that such a setback would create "dead space" behind the ADU.
Garage Size Restriction: Staff's previous recommendation would have placed a de-facto
restriction of 400 square-feet for a garage attached to an ADU. This proposal was intended to maintain a proportional relationship between an ADU and attached garage. Some cities have taken a similar or more restrictive approach, such as Mountain View who restricts garages to 200
square-feet, while others simply include uninhabitable area in the allowable ADU size
maximum.
However, some community members have argued that 400 square-feet is not sufficient to accommodate a two-car garage. Although staff disagrees with this assertion, the status quo has
not resulted in any indefinable harm such that a specific restriction may not be necessary. Even
without a specific restriction, the size of a garage would nonetheless be restrained by the FAR
and Lot Coverage maximums.
Planning Commission Study Session – March 12, 2019 Page 7
PLN2017-375 ~ Accessory Dwelling Units.
Options Descriptions
Option 1 No Restriction
Maintain the status quo of allowing attached garages to be as large as the
FAR and Lot Coverage would allow.
Option 2 Specific
Restriction
The Commission may recommend a specific size restriction for an attached
garage, such as staff's recommendation for 400 square-feet or a smaller or
larger size, as the Planning Commission deems appropriate.
Height: Historically, and in previous draft ordinances, the City has permitted ADUs at a
maximum height of 14-feet consistent with the standard for other detached structures such as
garages and workshops. However, as reflected in the development standard comparison table (reference Attachment 6), the height maximum can be increased. Generally speaking, increased height provides greater interior volume that can make an ADU feel "roomier," and also allow for
more sunlight due to higher window placement. Of course, a taller structure is also more evident
from neighboring properties.
Options Descriptions
Option 1 Current Standard Maintain the maximum 14-foot height standard.
Option 2 Taller Height
An increase in building height could be permitted and tied to a proportionally
greater side and rear setbacks, in the same manner that the City controls the
height other structures. Consistent with other cities, staff would encourage a
maximum height of no greater than 16- to 18-feet.
Option 3
Relative to
Primary Dwelling
The height of the ADU could be restricted by requiring the roof pitch to match
the predominant roof pitch of the primary dwelling. In this manner, the
maximum height would be defined by the building's width in combination with the roof pitch to create a proportional relationship between the dwellings.
Second-Story: Some Commissioners expressed openness to allowing a second-story option for an ADU. The following (not-mutually exclusive) options may be considered, however, it must be
noted that State law prohibits establishment of a setback greater than 5-feet for an ADU "that is
constructed above a garage".
Options Descriptions
Option 1
Existing Second-
Story Area
The least impactful option would be to allow an ADU to be created from a
primary dwelling's existing second-story living area. Since the second-story
would already be in existence, it would comply with the applicable setbacks
such that the State's 5-foot restriction would not be applicable.
Staff Note: State law requires these ADUs to have "independent exterior access from the existing residence" such that an exterior stairway up to the
ADU would be required.
Option 2 New Second-
Story Area
An ADU could be permitted as a second-story addition to an existing primary dwelling. However, to bypass the State's 5-foot setback maximum, the
allowance for a second-story ADU addition would have to be restricted to
areas not above a garage. As noted above, an exterior stairway would also be
required.
Planning Commission Study Session – March 12, 2019 Page 8
PLN2017-375 ~ Accessory Dwelling Units.
Options Descriptions
Option 3
Detached above Garage
An ADU could be allowed above an existing or proposed detached garage at
a five-foot setback. A corresponding height maximum would also need to be
established, somewhere in the range of 22- to 28-feet. The height could be
restricted by the height of the primary dwelling such that this option may only
be utilized on a property with a two-story primary dwelling.
Staff Note: An exterior stairway would generally be required, unless
sufficient space exists inside the garage to allow creation of an interior
stairway.
Option 4 (Not Allowed)
The Commission may recommend that ADUs on second-stories continue to
be prohibited.
Placement: As compared to accessory structures, the City has not generally limited the placement
of an ADU relative to the lot or the primary dwelling. This means that an ADU can be
constructed in front of, to the side, or behind the primary dwelling so long as the setback and separation standards are complied with. Staff's previous recommendations would have required that ADUs be located to the side or rear of the primary dwelling. This was intended to minimize
visibility of the ADU as to maintain the "ancillary" nature of the ADU as well as to achieve a
consistent development pattern along the street.
Options Descriptions
Option 1 No Restriction
Since there is not an identified example where placement of an ADU has been
found to be problematic, continuing the status quo may be appropriate in
order to provide maximum flexibility to homeowners.
Option 2
Behind and/or
Side of the
Primary Dwelling
Staff's previous recommendation would prohibit an ADU from being placed
in front of the primary dwelling. A stricter version of this option would
require the ADU to be placed behind the primary dwelling to significantly
minimize its visibility. However, such a restriction could limit the ability of a homeowner to create an ADU if the primary dwelling is unusually sited on
the property.
Option 3 Rear Half of the
Lot
A third option would be restricting the placement of an ADU to the rear half of the lot in the same manner the City governs detached garages and
workshops. This would establish a spatial relationship between the lot and
ADU rather than to the primary dwelling.
Design Requirements: Staff had previously recommended elimination of design standards for
detached ADUs for various reasons as noted in the November 27, 2018 staff report (reference
Attachment 1). However, Commissioner Ching raised a valid point that if ADUs are to be allowed in the front of the house, then there probably is a need for design requirements if the
City wishes to avoid poorly-designed ADUs. As such, a decision on potential design standards is
directly related to the allowable placement of an ADU.
Planning Commission Study Session – March 12, 2019 Page 9
PLN2017-375 ~ Accessory Dwelling Units.
Options Descriptions
Option 1 (a) No Standards
Citywide
If ADUs are limited to the rear of lot and/or the primary dwelling, design
standards could be eliminated entirely.
Option 1 (b)
No Standards
Select Areas
The City only regulates the design of homes in certain neighborhoods (i.e.,
San Tomas, Campbell Village, and Downtown). In other neighborhoods, a
property owner may design their home however they wish so long as it
complies with applicable setbacks, FAR, etc. In this regard, design requirements could be eliminated only those neighborhoods where the City
does not regulate design.
Option 2
Match the
Primary Dwelling
If ADUs are continued to be allowed in front of and/or the side of the primary dwelling, design standards could be established. Since design standards
should be objectively defined, they would effectively require duplicating the
appearance of the primary dwelling in terms of building form, roof pitch
colors, and materials.
Staff Note: This approach would significantly limit the ability of homeowners to utilize lower-cost prefabricated structures or design for the
future in anticipation of construction of a new primary dwelling.
Parking: SB 229 and AB 494 reduced the maximum number of parking spaces for a detached
ADU to one space per unit or bedroom, whichever is less (except for certain limited
circumstances where no parking is required). Currently, the City requires one space per bedroom,
which requires the City to revise its parking requirement in some manner.
Options Descriptions
Option 1
Eliminate the Parking Requirement
Since State law allows an existing or new driveway to satisfy the parking
requirement, a parking requirement is now largely hypothetical. As most
properties have a driveway, creation of an ADU would not generally require creation of an actual parking space unless a homeowner desired one. As such, eliminating the parking requirement outright may be seen as simply
acknowledging this reality.
Option 2 Conform to State
Law
As staff had previously recommended, the Commission may recommend
modifying the parking requirement to one space per unit or bedroom,
whichever is less, consistent with the maximum allowed by State law.
Option 3
Require Parking in Limited
Circumstances
A compromise option could be to require parking only when the primary
dwelling does not have its requisite two parking stalls, as Cupertino has
implemented. Thus, if the primary dwelling has no parking or only one space
the homeowner would either need to bring the primary dwelling into compliance or provide a parking space for the ADU.
Staff Note: This approach may be viewed as inconsistent with Legislature's
intent that cities treat ADUs as normal residential land use. In this regard, if
the City would allow an addition without regard to existing parking,
construction of an ADU should be given the same consideration
Planning Commission Study Session – March 12, 2019 Page 10
PLN2017-375 ~ Accessory Dwelling Units.
Additional Discussion Areas
Junior ADU: State Law provides for Junior Accessory Dwelling Units (JADU), which are quasi-
independent living units created from a bedroom within an existing residence. A JADU is
differentiated from an ADU by the lack of a private bathroom, but is required to have a small
kitchenette. Further, State law limits the size of an ADU to no more than 500 square-feet and prohibits imposition of a parking requirement (reference Attachment 7 – HCD FAQ).
In effect, a JADU provides homeowners the ability to take on a roommate with a greater degree
of privacy without having to construct a fully independent dwelling. In the context of providing additional housing options, JADUs do not have a discernable downside in as much as they provide for greater housing choices.
Options Descriptions
Option 1
Prohibit ADUs
State law does not require cities to allow JADUs. If the Commission does not
believe that they are necessary they do not need to be allowed.
Option 2
Allow either an ADU and JADU
If the Commission wishes to allow JADUs, the Commission may recommend
that either a JADU or an ADU be permitted, but not both. Of the cities that have allowed JADUs, nearly all have taken this approach.
Option 3 Allow both an ADU and JADU
The City may allow creation of both a JADU and ADU on the same property to maximize the degree of housing choice. Staff's inquiries have revealed the cities of Santa Rosa, Encinitas, and Sausalito have implemented this option.
Below-Market-Rate (BMR) Incentive: The draft ordinance previously considered by the Planning Commission would have tied the allowable size of an ADU to a below-market-rate
(BMR) incentive. Under the proposed standard, a homeowner would have been allowed a 700
square-foot (1 bedroom/1 bathroom) ADU by right. However, allowance for a larger ADU, up to
1,200 square-feet (2 bedrooms/2 bathrooms), would have been predicated on the homeowner voluntary deed restricting the ADU as a "lower-income" BMR unit.
At the public hearing, residents and some members of the Planning Commission expressed
concern that restricting the rental rates as a BMR unit would make constructing an ADU cost
prohibitive. There was also a concern that income restrictions for occupants of a BMR ADU could potentially displace family members in certain situations.
As requested, staff performed research on the financial implications of this approach. This
research involved a return-on-investment comparison between construction of a market-rate 700
square-foot (1-bedroom) ADU to an 1,200 square-foot (2-bedroom) BMR ("lower-income") ADU, taking into account prevailing construction cost, market- and below-market-rate rental
rates, and estimated loan cost amortized over 15 years (i.e., the typical term for a home equity
loan).1 Based on this analysis, it is evident that even taking into account the higher amount of
rent permitted for a larger size 2-bedroom ADU unit, the delta between construction/financing
and restricted BMR rent would result in an ongoing monthly loss for the period of financing.
1This research involved identifying comparable ADUs for rental comparison, contacting various construction companies for estimated per/sq. ft. construction cost which was compared to the City's permit valuations, and accounting for various "soft cost" including design, permit, school, and park fees. Financing cost assumed home
equity loans of $200,000 and $300,000 for a 700 sq. ft. and 1,200 sq. ft. ADU, respectively, at a 6.5% interest rate.
Planning Commission Study Session – March 12, 2019 Page 11
PLN2017-375 ~ Accessory Dwelling Units.
Metric 700 SF (1-Bed)
Market-Rate ADU
1,200 SF (2-Bed)
BMR Unit
Construction Cost $210,000 $336,000
Monthly Rent $2,500 $1,470
Average Monthly Financing Cost $1,575 $2,200
Monthly Gain/(Loss) $925 $(720)
As an alternative, the Commission may wish to consider linking a BMR incentive to the existing
owner-occupancy requirement. Currently and as previously proposed, a homeowner may only rent either the primary dwelling or the ADU at any given time. The other dwelling unit must
either be owner-occupied or remain unoccupied. The intent of this restriction is to maintain an
ADU as an accessory component of the primary dwelling, not to facilitate speculative
development. However, the ability to be relieved from this restriction would provide
homeowners the ability to retain their property should they need to move, which otherwise would not generally be possible.2 Elimination of this restriction would then be advantageous to
the homeowner by providing flexibility that had not previously existed while creating a BMR
unit that could potentially count towards the City's Regional Housing Need Allocation (RHNA)
obligation. This approach has several advantages over staff's previous recommendation:
•Is entirely voluntary without imposition of a new restriction(s);
•May be requested by a homeowner any time, not just at time of building permit issuance,
allowing greater flexibility;
•Can be applied to existing and future ADUs; and
•Would be more financially viable since the market-rate rent of the primary dwelling
would effectively subsidize the affordable BMR rent for the ADU.
The City of Santa Rosa has recently implemented this incentive program with some success. In the year since it has been in effect, the City has executed six 30-year affordability contracts. The
primary downside would be the increased oversight obligation necessary to ensure compliance
with the applicable occupancy restrictions for both contracted properties and non-contracted
properties alike.
In terms of the concern that family members could be potentially forced to vacate a BMR unit if
their income should exceed the State limit, Santa Rosa staff did indicate that their contracts have
an opt-out clause should the homeowner wish to terminate the contract and resume occupancy of
the property. However, such a provision would prevent the BMR ADUs from counting as
affordable housing units for the City's RHNA obligation.
ADU Development Policy: Creation of ADUs will generally be a minor component of housing
production since their construction reflects the financial capacity of individual property owners.
Although numerous homeowners may wish to construct an ADU, many will be unable to do so
simply because of the cost of construction. In comparison, larger projects benefit from economies of scale that allow developers to construct housing at a lower cost-basis than
individual homeowners.
2 Peterson, K. (2018) Backdoor Revolution. Portland, OR: Accessory Dwelling Strategies, LLC.
Planning Commission Study Session – March 12, 2019 Page 12
PLN2017-375 ~ Accessory Dwelling Units.
As such, the Commission may wish to consider exploring whether new multi-unit projects over a certain size (e.g., 5-10 homes or more) should be required to include ADUs, in either an ordinance or adopted policy. Some developers, such as Lennar (Next Gen – Home within a
Home), have already begun to do this. Such an approach would effectively double the number of
housing units produced with new subdivision projects without. In addition to increasing the value
of the new housing projects (a positive from a developer's perspective), the potential rental income from an ADU may also facilitate mortgage financing since prospective buyers may be able to point to future rent as a source of income.
A variation of this concept, should a regulatory requirement be deemed too burdensome, would be to require certain housing projects to make the new units "ADU ready," such that the homes designed and outfitted with the requisite infrastructure (i.e., plumbing, electrical, etc.) to
accommodate an ADU. In this manner, even if a developer opts not to construct an ADU with
the initial construction, a future homeowner could create the ADU at a significantly lower cost.
Fire Sprinkler Requirements: To lessen the cost of construction for ADUs, State law specifies that "accessory dwelling units shall not be required to provide fire sprinklers if they are not
required for the primary residence". Unfortunately, that language has not been entirely effective
in relieving property owners from being required to provide fire sprinklers in new ADUs by the
County Fire District, who has taken a conservative interpretation of this provision. However, since the fire sprinkler requirements are adopted locally the City may modify them for further clarity. The key component of this issue is the ability for Fire to access or serve the ADU. A
future ordinance should include language that clearly explains when fire sprinklers are or are not
required.
Park Impact Fees: Currently, construction of an ADU incurs payment of a one-time park impact fee about approximately $7,500. Whether this fee remains appropriate—or whether it should be
applied to JADUs—will be discussed as part of the comprehensive park fee study that is
currently underway. It anticipated that the City Council will adopt a new park fee program before
the end of the fiscal year.
Attachments:
1. Planning Commission Staff Report, dated November 27, 2018
2.Fit Plan Scenario 1 – 6,000 SF Lot w/ Attached Garage
3.Fit Plan Scenario 2 – 6,000 SF Lot w/ Detached Garage4.Fit Plan Scenario 3 – 10,000 SF Lot w/ Attached Garage5.Fit Plan Scenario 4 – 10,000 SF Lot w/ Detached Garage
6. Development Standards Comparison
7. JADU Frequently Asked Questions (FAQ)
ADU PLANNING COMMISSION STUDY SESSION SUMMARY (MARCH 26, 2019)
•Minimum Lot Size: No minimum lot size.
•Maximum ADU Size: Up to the State maximum of 1,200 SF, as restricted by the FAR/Lot
Coverage maximums (and not to exceed 50% of the living area of the primary dwelling unit for
an attached/interior ADU, per State law).
•Primary Unit Type: Allowed only in association with detached single-family homes.
•Placement: No restriction; may be in front, to the side, or the rear of the main house, subject to
design standards, as noted below.
•Setbacks/Building Separation:
Property
Line Setbacks
Front The same standard as for the primary dwelling unit
Interior Side (each) 5 feet
Street Side 12 feet
Rear 5 feet
Separation from Primary Dwelling
Unit
If located behind the primary dwelling unit 10 feet
If located to the side of the
primary dwelling unit 5 feet
•Garage Size Limit: No limit (other than restricted by the FAR/Lot Coverage maximums).
•Maximum Height: Not exceed the height/# of stories of the main home.
•Second-Story: (1) Allow an ADU to be created from existing second-story space; (2) allow an
ADU as a second-story addition, but not above an attached garage; and (3) allow an ADU above
a detached garage on a property with an existing/proposed 2-story home (not to exceed the
height of the house). Exterior stairway to the ADU will be required.
•Design Requirement: Require design consistency with the main house only if the ADU is located
in front of or to the side of the main house. Also include privacy requirement for 2-story ADUs.
•Parking: One parking space per ADU, the maximum allowed by State law (main home does not
need to be parking compliant).
•Junior ADUs: Allow both a JADU and ADU on the same property.
•Owner Occupancy: Maintain an owner occupancy requirement.
•BMR Incentive: No clear resolution.
•ADU Development Policy: Require subdivisions with 5+ homes to include 20% of the units as
“ADU-ready”.
Attachment 2
City
(Ordinance Link) STANDARDS
Benicia
(BMC Sec. 17.70.060)
6.In the H historic overlay district, an accessory dwelling unit shall conform to the following additional
requirements:
a.Detached accessory dwellings and building additions shall be located behind the primary dwelling
and shall not exceed the height or footprint of the primary dwelling.
b.An attached accessory dwelling unit shall not result in a rooftop addition or any increase in building
height.
c.A building addition for an attached accessory dwelling unit shall be inset or separated by a connector
that is offset at least 18 inches from the parallel side or rear building wall to distinguish it from the
primary dwelling. A building addition for an attached ADU shall not extend beyond the side wall of the
primary dwelling.
d.Exterior building and trim materials shall be horizontal wood siding or shingles. However, if stucco is
the predominant finish for the primary residence, then a stucco exterior may also be applied to the
accessory dwelling. Synthetic stucco (e.g., EIFS or DryVit) is prohibited.
e.The exterior walls of an accessory dwelling shall utilize the same base and trim colors as the primary
residence.
f.The roof shall utilize the same material and color as the primary residence and shall match the
primary residence in overall appearance.
g.Gutters shall not be constructed of plastic or PVC materials and shall apply a similar profile as gutters
located on the primary residence.
h.Windows shall be taller than they are wide or shall match the proportions of the primary dwelling’s
windows. Windows in small spaces, such as bathroom windows, may be horizontally oriented.
i.Window pane divisions shall be true or simulated divided lites (muntins applied to both the interior
and exterior of the glass).
j.Window frames shall be painted or factory-finished. No metallic finishes such as silver or bronze
anodized aluminum are permitted.
k.Dormers shall not face an adjoining side yard.
Attachment 3
City
(Ordinance Link) STANDARDS
Pasadena
(PMC Sec.17.50.275)
4.Historic Districts. Accessory dwelling units are prohibited in historic districts (e.g., National Register,
Landmark, etc.) unless the accessory dwelling unit is one of the following:
a.A converted accessory dwelling unit; or
b.A newly constructed accessory dwelling unit that is not visible from the public right-of-way.
5.Individually Designated Historic Properties.
a.Newly constructed accessory dwelling units are prohibited on individually designated historic
properties.
b.Converted accessory dwelling units are permitted on individually designated historic properties.
D. Development standards. Except as identified in this Subsection, accessory dwelling units shall comply
with all of the development standards (e.g., encroachment plane, floor area, height, lot coverage,
setbacks, etc.) that apply to the primary residence.
1.Converted Accessory Dwelling Units.
…
e.Windows and doors for historic properties. Windows and doors (including opening and garage
doors) for historic properties that are original to the structure are required to be retained,
unless this requirement prevents creation of the accessory dwelling unit.
Glendale
(GMC Sec. 30.34.080)
6.For properties listed, or identified on a historic survey as potentially eligible on the California Register of
Historic Places, Glendale Register of Historic Properties, or any property in an adopted or nominated historic
district overlay zone, any exterior changes to an existing property to create an accessory dwelling unit shall
not be visible from the public street or sidewalk right-of-way immediately adjacent to the property and shall
not alter any defining historical characteristic.
City
(Ordinance Link) STANDARDS
Santa Barbara
(SBC 30.185.040)
8.Design Style. New detached or attached accessory dwelling units shall be compatible with the design of
the primary residential unit regarding style, fenestration, materials, colors and details if the accessory
dwelling unit meets any of the following:
…
d.Located on a site on which there is a historical resource listed on the National Register of Historic
Places or the California Register of Historic Places, or designated as a City of Santa Barbara Landmark or
Structure of Merit, or located in a designated historic district; or
9.Privacy Standards. The construction of an accessory dwelling unit where any portion of the proposed
construction is either: two or more stories tall, or 17 feet or taller in building height, shall comply with the
following:
…
…An applicant may propose an accessory dwelling unit that does not meet these design criteria subject to
approval by the Single Family Design Board or Historic Landmarks Commission, as appropriate.
U. Protection for Historic Resources. No accessory dwelling unit or junior accessory dwelling unit shall be
permitted if the proposal would cause a substantial adverse change in the significance of a historical
resource listed on the National Register of Historic Places or the California Register of Historic Places, or
designated as a City of Santa Barbara Landmark or Structure of Merit, or located in a designated historic
district. The Community Development Director shall make this determination by reviewing the proposal for
compliance with appropriate Secretary of Interior’s Standards for the Treatment of Historic Properties with
Guidelines for Preserving, Rehabilitating, Restoring and Reconstructing Historic Buildings.
City
(Ordinance Link) STANDARDS
Santa Rosa
(SRC Sec. 20-42.130)
B.
…
3. Shall not be allowed on, or adjacent to, real property that is listed in the California Register of
Historic Places.
Standards for Historic Preservation Districts.
a. Applicability. The requirements outlined below shall apply to new accessory dwelling units within
the Historic (-H) Combining District.
b. Development standards.
(1) Through photographs, color and material boards, architectural elevations, and other means,
the applicant shall demonstrate the consistency of the proposed design of accessory dwelling
unit’s colors, textures, materials, fenestration, decorative features and details, with that of the
time period of the residence’s construction and/or adjacent historic structures.
(2) For properties that are identified as a contributor to the District, through the preparation of
a historic resource survey by a qualified professional, the applicant shall demonstrate that the
proposed accessory dwelling unit will not negatively impact historic resources on the property,
and will be consistent with Secretary of the Interior Standards for Treatment of Historic Properties
as applicable.