ADUs_HAB_032223Housing Advisory Board –March 22, 2023
Accessory Dwelling Unit
Regulation Update
Planning & Development Services
Purpose:
Make a recommendation to City
Council on Ordinance 8571
What is an ADU?
•Small residence sharing lot with larger
main house
•Independent, self-contained living space
Scope -ADU Update Project
City Council Work Program Priority Objective:To increase the allowance of
ADUs in the community by:
•eliminating the ADU saturation limit
•modifying the ADU size limits and/or method of measurement
•clarifying and simplifying the regulations
•improving the approval processes
2023 Engagement
•Review 2016-2018 Public Engagement –Saturation & Size
•Community Connectors-in-Residence –1/13
•Planning Board –1/17
•Housing Advisory Board –1/25
•City Council Study Session –1/26
•Board of Zoning Adjustment –2/14
•Be Heard Boulder
•Office Hours –March & April
•Ordinance Review Public Hearings –March -May
2022 Evaluation
ADU Background
Evaluation of 2018 Code Changes
Changes that reduced barriers
•Saturation limit
•Maximum size
•Minimum lot size
•Zoning districts
Remaining potential improvements
that would further reduce barriers
to ADUs
•Eliminate saturation limits
•Reconsider floor area and
measurement
•Extend approval expiration
•Height variance option
•Code clarification
•Process improvements
2022 ADU Owner Survey
•Sept. -Oct: HHS survey of ADU owners
•Comparable survey from 2017 and 2012
•212 responses,48% response rate
•Highlights:
•Greater % of ADUs used as space for visitors/relatives
•40% of owners chose Affordable ADU to reduce parking
requirement
Comparable City Research
Highlights –34 cities
•None of these cities have a saturation limit for ADUs
•Only a few have a minimum lot size
•Almost all cities limit 1 ADU per lot
•Boulder’s maximum size of detached ADUs smaller than most cities (though
many cities in Colorado tend to be lower than other states, 600-1,000). Typically
around 800 sf or a % of principal structure
•Variation on parking requirements –0 or 1, some waive if close to transit
•Almost all say ADU cannot be sold separately
•About half require owner occupancy
2023 ADU Update
Focus Areas
ADU Update Project
City Council Work Program Priority Objective:To increase the allowance of
ADUs in the community by:
•eliminating the ADU saturation limit
•modifying the ADU size limits and/or method of measurement
•clarifying and simplifying the regulations
•improving the approval processes
RL-1 & RL-2 Saturation Limit –20%
300 FEET
Saturation Limits 2019-2022
Does this address qualify
for an ADU?
We're curious if the 20% ADU saturation limit has already
been met for our property's area?
We would like to consider an ADU over the garage of our
home but need to confirm that the location is not
saturated first. How do we do that without submitting the
full application and $420 fee?
I'd like the saturation calculation for
this property to identify the possibility
of ADU.
We would like to check the
saturation for an ADU
Is an ADU possible for this property address? My
understanding is that the density of ADUs already in an
area impacts the availability.
1. Is an allocation available at this site –i.e. has this
area hit saturation or not?
Can you confirm that there is still availability
to build an ADU in the neighborhood of the
address
I am interested in adding an ADU to my property and would like
to connect with a project specialist to determine if this is
allowable under the saturation rate rules.
It appears that there is one ADU across the street, but I'm
not sure how many houses are within the 300 ft radius to
know if the saturation limit would be reached.
I am wondering if my property would be eligible based on
the 300 foot radius, 20% ADU saturation guideline? Could
someone please help me with this calculation? If my home is
not eligible, I don't want to go through the full process.
Saturation Limit Inquiries
Proposed Code Change
Eliminate the 20% saturation limit within 300 feet of
properties in the RL-1 and RL-2 zoning districts.
Size Limits
(Market Rate)
Attached:
1/3 size of main
house or 1,000
square feet
Detached:
550 square feet
Ex: 1,500 sq. ft. house =
500 sf ADU
BOZA Variances 2019 -2022
4
Approved
All 4: Attached exceeding maximum floor area
1,027 sf
1,216 sf
1,266 sf
1,500 sf
Size examples –Detached on alley
Size examples –Detached on alley
Detached no alley
Attached
Proposed Code Change
ADU Type Current Size Limit Proposed Size Limit
Attached 1/3 of principal unit or 1,000
square feet, whichever is less
1/2 of principal unit or 1,000
square feet, whichever is less
Detached 550 square feet 800 square feet
Affordable
Attached
1/2 of principal unit or 1,000
square feet, whichever is less
2/3 of principal unit or 1,200
square feet
Affordable
Detached 800 square feet 1,000 square feet
Historic
Attached
1/2 of principal unit or 1,000
square feet, whichever is less
2/3 of principal unit or 1,200
square feet
Historic
Detached 1,000 square feet 1,000 square feet
>Remove unique ADU floor area measurement definition
>Modify size limits:
Code clarification
•Extend approval expiration period
•Flexibility for height of existing structures
•Lockable separation of attached ADUs
•Limited accessory units
•Owner occupancy –LLCs and temporary rental
exemptions
•Public notice requirement
•Change ADU from [C] to [A]
•Typical building permit
expiration timeline applies
Code clarification
•Extend approval expiration period
•Flexibility for height of existing structures
•Lockable separation of attached ADUs
•Limited accessory units
•Owner occupancy –LLCs and temporary
rental exemptions
•Public notice requirement
•Updated detached ADU height
standards
•Existing structures can be
reused if no change to size,
height, roof form (no 25 ft max)
•Complex standards related to
roof pitch removed
Code clarification
•Extend approval expiration period
•Flexibility for height of existing structures
•Lockable separation of attached ADUs
•Limited accessory units
•Owner occupancy –LLCs and temporary
rental exemptions
•Public notice requirement
Specifically included in Attached
ADU standards
Code clarification
•Extend approval expiration period
•Flexibility for height of existing structures
•Lockable separation of attached ADUs
•Limited accessory units
•Owner occupancy –LLCs and temporary
rental exemptions
•Public notice requirement
Removed from code
Code clarification
•Extend approval expiration period
•Flexibility for height of existing structures
•Lockable separation of attached ADUs
•Limited accessory units
•Owner occupancy –LLCs and temporary
rental exemptions
•Public notice requirement
•Clarity added to definition of
owner occupancy
•Added specific language about
documents to confirm owner
occupancy
Code clarification
•Extend approval expiration period
•Flexibility for height of existing structures
•Lockable separation of attached ADUs
•Limited accessory units
•Owner occupancy –LLCs and temporary
rental exemptions
•Public notice requirement
ADUs an [A] use to implement
one-step review, do not require
public notice
Process Improvements
•One-step review
•Addressing
•Declarations of use
•Self-service handouts/videos
Next Steps
•Public engagement
•Planning Board public hearing: April 4
•City Council 1st Reading: April 20
•City Council 2nd Reading: May 4
•May/June: Process
improvement/preparation
•Late summer effective date of
ordinance
Suggested Motion
Housing Advisory Board
recommends that City Council
adopt Ordinance 8571, amending
Section 4-20-18, “Rental License
Fee,” Title 9, “Land Use Code,” and
Title 10 “Structures,” B.R.C. 1981,
to update the regulations for
accessory dwelling units.