Understanding Portland City Code 24.85: Seismic Upgrade Requirements for Existing Buildings
Many property owners and developers in Portland are familiar with zoning regulations and building permits. Far fewer, however, fully understand Portland City Code Chapter 24.85, which governs seismic upgrade requirements for existing buildings.
Portland City Code 24.85 is one of the most significant—and often overlooked—regulations affecting existing buildings in Portland
This code frequently comes into play during renovations, additions, or changes in occupancy and often introduces significant cost implications that are not anticipated early in a project.
For this reason, Chapter 24.85 is one of the most important and commonly misunderstood regulations affecting existing buildings in Portland.
What Is Portland City Code 24.85?
Portland City Code Chapter 24.85 establishes requirements for seismic evaluation and, in some cases, seismic strengthening of existing buildings when certain types of work are performed.
Unlike standard building code provisions, Chapter 24.85 is:
Triggered by project scope, not just new construction
Applied specifically to existing buildings
Intended to improve life safety and seismic resilience
It provides an alternative framework for seismic upgrades that can be used in lieu of full compliance with current OSSC seismic provisions for existing structures.
Why This Code Often Catches Projects Off Guard
One of the most important aspects of Chapter 24.85 is that it is not always obvious during early project planning.
Developers and property owners often discover these requirements:
during permit review
after design has progressed
or when project costs are already established
In some cases, required seismic upgrades can add substantial cost, potentially affecting project feasibility.
This is why early code analysis is critical for projects involving existing buildings.
When Seismic Upgrades Are Triggered
Chapter 24.85 does not apply to every project, but it can apply to even small tenant improvements. It is triggered by specific types of work performed on an existing building.
Change in Occupancy
A change to a higher hazard occupancy classification can trigger seismic upgrade requirements under Portland City Code 24.85.
Common Trigger Conditions
Seismic evaluation or upgrades may be required when a project involves:
An increase in occupant load
A change to a higher risk occupancy classification (e.g., Business → Assembly)
Same Occupancy, Different Use
Even when the occupancy classification remains the same, seismic upgrades may still be triggered if the change in use results in a significant increase in occupant load or hazard classification.
Exceptions and Thresholds
Limited exceptions may apply where:
Cumulative changes remain below defined thresholds
Occupant load increases fall within allowable limits
The overall impact to the building is considered minor
However, these exceptions are highly dependent on:
Accurate interpretation of the proposed use
Review of existing permit history
Understanding the existing building code at the original permitting and which occupancy benchmarks apply to the building
Why Early Analysis Matters
A properly performed code analysis can:
Clarify whether seismic upgrades are triggered by the proposed design
Identify potential exceptions or alternative approaches
Define project limitations early in the design process
This level of early evaluation significantly increases the likelihood of a successful and predictable permitting outcome, while helping avoid costly surprises later in the project.
Section 2: Additions and Alterations
Additions and alterations to an existing building can trigger seismic upgrade requirements under Portland City Code 24.85, particularly when the work affects structural systems or represents a significant investment in the building.
Common Trigger Conditions
Seismic evaluation or upgrades may be required when a project involves:
An addition that increases building area or height
Structural modifications to the existing building
Alterations that affect load paths or lateral systems
Work that exceeds defined valuation thresholds (particularly in older buildings)
Impact on Existing Building
While new work must comply with current code, Chapter 24.85 also considers how the proposed work impacts the existing structure as a whole.
This may result in:
Seismic evaluation of the entire building, not just the addition
Required improvements to existing lateral systems
Integration of new and existing structural components
Exceptions and Flexibility
The code provides some flexibility depending on project scope and in some cases alternative compliance paths may be available through engineering analysis
Why Early Analysis Matters
A properly performed code analysis can:
Determine whether the scope of work triggers seismic requirements
Evaluate whether phased or alternative compliance approaches are viable
Align project scope with budget and feasibility constraints
Early coordination helps prevent situations where a project triggers unexpected full-building seismic upgrades during permit review.
Section 3: Catastrophic Damage and Repairs
Buildings that have experienced significant damage may trigger seismic upgrade requirements under Portland City Code 24.85 when repairs are undertaken.
Common Trigger Conditions
Seismic evaluation or upgrades may be required when a project involves:
Fire damage affecting structural elements
Earthquake damage or compromised structural systems
Major repairs that impact the building’s structural integrity
Extent of Damage Considerations
The level of required seismic work is generally based on:
The extent of the damage
The portion of the building affected
The age and type of construction
Exceptions and Thresholds
Limited exceptions may apply where:
Damage is considered minor or non-structural
Repairs do not significantly affect the overall structure
Section 4: Pre-1974 Buildings
Buildings constructed prior to modern seismic codes are a primary focus of Portland City Code 24.85.
Common Trigger Conditions
Seismic evaluation may be required when a project involves:
Alterations to older buildings constructed before 1974
Work exceeding defined valuation thresholds
Projects that significantly modify the existing building
Evaluation Requirements
In these cases, the code may require:
A seismic evaluation of the existing building
Analysis based on recognized standards such as ASCE 41
Key Consideration
A seismic evaluation does not always require a full upgrade, but it may identify deficiencies that need to be addressed depending on the scope of work.
How Seismic Compliance Is Evaluated
Seismic evaluation and retrofit design under Chapter 24.85 are based on:
ASCE 41 – Seismic Evaluation and Retrofit of Existing Buildings
This standard establishes performance objectives such as:
BPOE (Basic Performance Objective for Existing Buildings)
BPON (Performance Equivalent to New Buildings)
These frameworks define how a building is evaluated and what level of improvement may be required.
Why Early Code Analysis Matters
Chapter 24.85 is rarely the primary focus of a project but it can quickly become one of the most important factors affecting:
project cost
design strategy
permitting timeline
overall feasibility
Projects that evaluate seismic requirements early can:
avoid redesign during permitting
make informed decisions about scope
plan for potential upgrade costs
evaluate whether phased approaches are viable
Projects that do not account for these requirements early often encounter unexpected delays and cost increases during permit review.
The Role of an Experienced Portland Architect and Owner’s Representative
Chapter 24.85 is often not a primary design driver at the outset of a project, but it can quickly become one of the most critical factors affecting feasibility.
Architects and owners representatives with specific experience in Portland’s seismic upgrade requirements play a key role in identifying and managing these triggers early in the process.
This includes:
Determining whether seismic triggers apply based on proposed scope
Interpreting how occupancy, valuation, and prior permit history affect compliance
Coordinating with structural engineers on ASCE 41-based evaluations
Developing compliance strategies that align with project goals and constraints
With a thorough and properly structured analysis, it is often possible to identify pathways that limit scope, phase improvements, or avoid unnecessary upgrades, depending on the specifics of the project.
In many cases, projects initially believed to be infeasible due to seismic requirements can be restructured into viable projects through a detailed understanding of how Chapter 24.85 is applied.
Planning a Project in Portland
For property owners and developers considering renovations, additions, or occupancy changes in Portland, Chapter 24.85 should be evaluated early—particularly for existing and older buildings.
Understanding how and when seismic upgrades are triggered can directly influence:
Project feasibility
Budget and cost exposure
Design approach and scope definition
Permitting strategy and timeline
Early evaluation allows project teams to make informed decisions about whether to proceed, modify scope, or adjust strategy before significant design work is undertaken.
About JR DBA
JR DBA provides commercial architecture services, project feasibility / consulting, and owner representation services in the Portland region, with a focused expertise in Portland City Code 24.85 and seismic upgrade analysis.
Through detailed code evaluation and strategic project planning, JR DBA has helped projects navigate complex regulatory constraints—often transforming projects initially considered infeasible into code-compliant and financially viable outcomes.
