Eli’s Informal (and unauthorized) Code Guide
For
Small, Detached Structures
In the
City of Portland
Disclaimer: This guide is not authoritative, is overly simplified in places, and should not be relied on for accuracy. To get the
real scoop, read up on the zoning and building codes directly and/or consult with Bureau of Development Services staff on the
1st floor of the 1900 SW 4th Ave. building in downtown Portland.
ADU (Accessory Dwelling Unit)
Description,
Examples
A stand-alone dwelling unit with legal
kitchen and bathroom
Permitted Accessory
Structure
Habitable1: detached
bedroom2
Unpermitted Accessory
Structure
Habitable: N/A
Code
References
Not habitable: storage
shed, chicken coop, kid’s
fort, wood shed,
greenhouse
Zones allowed
Allowed in all R zones, with certain
limited exceptions
Not habitable: garage,
artists’ studio, yoga
studio, guest house
(limited use)
Allowed in all R, C, E and I zones
33.205.020
33.120.280
33.130.265
33.140.270
Per Chapter 29.10 Definitions, “Habitable room or space is a structure for living, sleeping, eating or cooking. Bathrooms,
toilet compartments, closets, halls, storage or utility space, and similar areas are not considered habitable space.”
2 If plans for a habitable, detached accessory structure suggest the potential for that the structure to be used as an independent
dwelling, the city may require the applicant to sign and record a ‘Second Sink Agreement’ against the property.
1
ADU (Accessory Dwelling Unit)
Height limit
18’ 3
Unpermitted Accessory
Structure
10’
Code
References
33.205.030
33.110.215
Square footage
Lesser of 800 sq. ft. or 75% the size of
200 sq. ft.
the primary dwelling
 Total building coverage of all detached covered accessory structures may not exceed
15 percent of the total area of the site in the R zones
 Building coverage of any one detached covered accessory structure (including ADUs)
may not be greater than the building coverage of the primary structure in the R zones
 Total building coverage of all structures (primary and accessory) may not exceed the
limit for the zone. This limit is 2,250 sq. ft. for a 5,000 lot in the R5 zone.
33.205.030
C. 6
33.110.250
D. 1, 2
33.120.280
D. 1, 2
33.110.225
33.120.225
Building
coverage of the
lot
Location on the 60’ from the front property line or 6
lot
feet behind the existing house.
Permitted Accessory
Structure
Base zone
requirements (30’ in
the R5 zone)
No special restrictions
No special restrictions
33.205.030
D. 1
Setbacks
Base zone setbacks apply (10’ front yard and 5’ side/rear yard in the R5 zone)
Design
standards
Must match exterior finish materials,
roof pitch, exterior trim, window
proportions and orientation, and eave
projections (with limited exceptions)
of the primary residence. There is
more flexibility in design compatibility
standards for conversions of existing
structures
3
N/A
For gable roofs, height is measured to the mid-point of the gable
N/A
33.110.250
C. 4. b
33.205.030
C. 7 – 11
33.205.030
D. 4. c, d
ADU (Accessory Dwelling Unit)
Design review
or community
design
standards
Occupancy
Fees
Permitted Accessory
Structure
Applies to all permitted detached accessory structures in design
overlay zones
Unpermitted Accessory
Structure
N/A?
Code
References
33.420
33.420.055
33.218
Habitable. Maximum number of
individuals residing in both units
(primary and ADU) may not exceed the
number allowed for a household 4
Not for habitable use. If
habitation is desired, the
structure must be
permitted, regardless of
size or height
33.205.030
C. 2
Building permits and Systems
Development Charges (SDCs) apply.
SDCs for ADUs are waived through
June 30, 2013
Only habitable if
permitted as such,
which requires
compliance with
structural and
fire/life/safety codes
Building permits
None for the structure.
Trade permits for
electrical, plumbing
and/or HVAC service to
the detached structure
may be purchased
separately.
General Notes
 Certain zoning code requirements, including setbacks, lot coverage, size limits, and design standards, can sometimes be
modified through a zoning adjustment process. See section 33.805 of the zoning code or contact BDS staff for
additional information.
Maximum household size, per ‘definitions’ section of the zoning code: “One or more persons related by blood, marriage, legal
adoption or guardianship, plus not more than 5 additional persons, who live together in one dwelling unit; or one or more
handicapped persons as defined in the Fair Housing Amendments Act of 1988, plus not more than 5 additional persons, who
live together in one dwelling unit.”
4

There is wide latitude in building methods and materials for foundations, walls, roofs… in unpermitted structures.
However, if a structure is not permitted initially, subsequent conversion to a different use for which a permit is
required (such as a habitable structure) could be difficult or impossible, depending on the original building methods
and materials used.
Additional Resources
Portland Zoning code:
http://www.portlandonline.com/bps/index.cfm?c=31612
Information and code guide for conversions of garages or attics to habitable use:
http://www.portlandonline.com/bds/index.cfm?c=38148