HomeMy WebLinkAboutA043 - Staff report on State Law Changes to Accessory Dwelling Unit (ADU) Zoning StandardsITEM #:46
DEPT:P&H
May 27, 2025
Staff Report
STATE LAW CHANGES TO ACCESSORY DWELLING UNIT (ADU) ZONING STANDARD
BACKGROUND:
In 2022, the City adopted standards for the construction of Accessory Dwelling Units (ADUs).
The adopted standards relied upon the City's current accessory building provisions related to
size and setback encroachments. ADUs were required to be detached from the principal
home, include one parking space in addition to that of the single-family home, and at
least one of the two units must be the primary residence of the owner. The City allowed
for reduced setbacks in the rear yard for both one story and two-story structures of as
little as three feet.
On May 1, the Governor signed into law Senate File 592 (attached). This legislation,
which will go into effect on July 1, 2025, requires cities to allow for ADUs that meet
minimum standards. In general, the law is trying to support new ADU construction by
requiring cities to allow for an ADU with any single-family home and to treat the ADU
the same as a single-family home. The new law does not preempt restrictive covenants.
The law contains some standards that conflict with those adopted by the City, and the
City standards must now be modified to rectify these conflicts.
A summary of the conflicting provisions of the new state law and the existing City standards
follows below:
Standards that Differ
Standards City Standards State Law Minimums to
Allow
Maximum Size 900 square feet for entire
accessory structure
1,000 square feet for ADU, or
50% of the single-family home
size, whichever is greater
Parking 1 space for ADU, + 2 spaces
for a home
None required beyond 2
spaces
Residency Requirement Owner Primary Residence on
site No limitation allowed
Structure Type Detached only
Attached or Detached (believe
it limits conversions)
Use of Mobile Home Not Allowed Allowed when on a foundation
Maximum Height
Up to 80% of single-family
home height or 20 feet,
whichever is lower
No different than single family
home maximums
Bedroom Limitation 1 bedroom maximum Not referenced
1
Rental/Occupancy
Treat same as SF house (3
adults for 1 bedroom)
Additional limits in Near
Campus Neighborhoods.
Treat the same as a SF house
(unclear if Near Campus
limitations will apply, they
should)
Design/Aesthetics
No specific standards, except
SF Overlay and Historic
District
Can’t treat differently than SF
home, can’t require matching
roof form, materials, colors.
OPTIONS:
Option 1 - Change local setback encroachments along with new State law requirements
Rear yard single family home setbacks are typically 20 feet. Accessory buildings of all types
are allowed to encroach for up to 20% of the rear yard area with a minimum setback of 3 feet,
including for two story accessory buildings. Eliminating or reducing the allowed setback
encroachments for large structures or two-story structures is an option, if Council is
concerned about compatibility due to the new state mandated changes. Council could
elect to continue the rear yard exception for properties with an alley that may have a
ADU structure located above a garage.
Option 2 - Only make changes needed to meet new State law
This option would be the most permissive as it would incorporate all the new state
allowances and continue the City's local encroachment options.
Option 3 - Make Other Changes along with new State law
The City Council can modify other standards as long as they treat ADUs and single-
family homes the same. Because of the state's one-size-fits-all approach, other
changes to address potential ADU issues such as requiring more parking for a single-
family homes, increased setbacks, reduced lot coverage, etc. may be punitive to single
family homeowners that are only concerned about their home and typical accessory
structures.
STAFF COMMENTS:
If Council desires to modify some of the current standards to be more restrictive
(Option 1) while updating zoning standards to conform to the state law, an expedited
schedule is needed to potentially have new standards in place when the state law
becomes effective on July 1.
If the proposed changes affect Historic Resources, the Historic Preservation Commission
(HPC) has an advisory step before P&Z consideration and Council approval. Approval prior to
July 1 would require HPC to consider the changes on June 9, P&Z to review on June 18, and
a City Council hearing and three readings on June 24.
With City Council's guidance regarding how to proceed, Planning staff will work with City
Attorney to draft an ordinance and proceed through the amendment process.
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ATTACHMENT(S):
ADU State Law.pdf
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Senate File 592, p. 4
NEW SUBSECTION, 20. a. A city shall allow a minimum of
one accessory dwelling unit on the same lot as a single family
residence in accordance with the following conditions:
(1) An accessory dwelling unit shall comply with all
applicable building regulations as defined in chapter 103A,
(2) An accessory dwelling unit shall not exceed one thousand
square feet or fifty percent of the size of the single family
residence, whichever is larger.
(3) An accessory dwelling unit shall be prohibited or
limited only to the extent that a state historic building code
restriction, as adopted by a city in accordance with section
103A.43, subsection 3, a deed restriction, or a rule of a
common interest community, as defined in section 499C.1, limits
or prohibits the construction or use of an accessory dwelling
unit. The imposition of an ordinance, motion, resolution, or
amendment regulating accessory dwelling units that is more
restrictive when applied to a common interest community than
when applied to a single family residence is prohibited.
(4) If a manufactured home as defined in section 435.1,
subsection 3, or a mobile home as defined in section 435.1,
subsection 5, is used as an accessory dwelling unit, the
manufactured home or mobile home shall be converted to real
property by being placed on a permanent foundation and assessed
for real estate taxes pursuant to section 435.26.
b. Except as otherwise provided in paragraph or by state
law, a city shall not impose any of the following limitations
or restrictions:
(1) Requirements related to the placement or appearance of
an accessory dwelling unit that are more restrictive than those
imposed on a single family residence including but not limited
to the following: maximum building heights; minimum setback
requirements; minimum lot sizes; minimum building frontages;
maximum lot coverages; density requirements; and aesthetic
or architectural standards or requirements. Additionally, a
city shall not require an accessory dwelling unit to match the
exterior design, roof pitch, or finishing materials of the
single family residence.
(2) Regulations on the use of an accessory dwelling unit as
a rental property that are more restrictive than those provided
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Senate File 592, p. 5
for in subsections 9 and 16 of this section, section 414.1,
subsection 1, paragraph and chapter 562A.
(3) A requirement that the lot containing a single family
residence and an accessory dwelling unit have additional
parking beyond that required for a single-family residence or
payment of a fee in lieu of providing additional parking,
(4) Restrictions on the occupancy of either the single
family residence or the accessory dwelling unit by any of
the following manners: requiring the property owner to be
a resident; requiring a familial, marital, or employment
relationship to exist between the occupants of the single
family residence and the occupants of the accessory dwelling
unit; or restricting the occupancy of an accessory dwelling
unit based on income or age.
(5) A requirement of new or separate utility lines between
the accessory dwelling unit and public utility service
connections. However, if full utility access that includes
a separate metering system for billing purposes cannot be
provided to the accessory dwelling unit, then the city can
require new or separate utility lines.
(6) Imposition of a different city impact fee structure or
development standard for an accessory dwelling unit than those
used for the single family residence on the same lot.
(7) The requirement of improvements or repairs to public
streets or sidewalks beyond those imposed on the single family
residence on the same lot.
c, A city shall approve an accessory dwelling unit permit
application that meets the requirements set forth in paragraph
and by state law without discretionary review or hearing
and consistent with the time frame assigned to the approval of
a single family residence. An accessory dwelling unit permit
application shall not have a review timeline or schedule in
excess of a city's normal review schedule for a single family
residence. If the city denies an accessory dwelling unit
permit, the reason for denial shall be provided in writing
to the applicant and include any remedy necessary to secure
approval.
d, A city ordinance, motion, resolution, or amendment
regulating accessory dwelling units in a manner that conflicts
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Senate File 592, p. 6
with this subsection is void. Nothing in this subsection
prohibits a city from adopting an ordinance, motion,
resolution, or amendment that is more permissive than the
requirements provided in this subsection.
e. For the purposes of this subsection;
(1) ^Accessory dwelling unit^ means an additional
residential dwelling unit located on the same lot as a single
family residence that is either attached to or detached from
the single family residence.
(2) "^Detached" includes being part of an accessory structure
such as a detached garage.
(3) '^Dwelling unit'' means the same as defined in section
562A.6, subsection 3.
(4) ^Single family residence" means the same as defined
in section 562A.6, subsection 15, except to the extent that
a single family residence may share utility lines with the
accessory dwelling unit if full utility access that includes a
separate metering system for billing purposes can be provided
to the accessory dwelling unit.
AMY SINCmiR PAT GRASa2.EY
President of the Senate Speaker of the House
I hereby certify that this bill originated in the Senate and
is known as Senate File 592, Ninety-first General Assembly.
W. CHARLES SMITHSON
Approved I V 1^ , 2025
^ary ra the Senate
KIMXREYNOLDS
Governor
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