TL;DR (generated, confidence: high)

Portland's 2018 Major Residential Alteration and Addition (MRAA) ordinance regulates residential remodeling on properties with residential zoning, requiring building permits for projects that either remove over 50% of exterior walls or add over 500 square feet of interior space.

Key points:

MRAA applies only to residential structures with residential Comprehensive Map Designation; does not apply to commercial areas or multifamily residences (Major Residential Alteration and Addition Permit Requirements ↗)
Major alteration defined as removing more than 50% of exterior walls above foundation, measured in linear feet by story (Major Residential Alteration and Addition Permit Requirements ↗)
Major addition defined as adding more than 500 square feet of new interior space that expands the structure's footprint or envelope (Major Residential Alteration and Addition Permit Requirements ↗)
Building permit required; trade permits (electrical, mechanical, plumbing) likely needed for MRAA projects (Major Residential Alteration and Addition Permit Requirements ↗)
Exempt from MRAA: non-habitable accessory structures, conversions without exterior wall removal or footprint expansion, detached accessory dwelling units (Major Residential Alteration and Addition Permit Requirements ↗)
Rules established in 2018 by City Council; detailed in Portland City Code Chapter 24.55 and administrative rule ENB-25.01 (Major Residential Alteration and Addition Permit Requirements ↗)

Entities: regulation: Major Residential Alteration and Addition | code_reference: Portland City Code Chapter 24.55 | administrative_rule: ENB-25.01 | zoning_term: Comprehensive Map Designation | permit_type: building permit · trade permits | threshold: 500 square feet · 50%

Major Residential Alteration and Addition Permit Requirements

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Source: Major Residential Alteration and Addition Permit Requirements ↗ Last modified: Sun, 19 Apr 2026 20:05:52 GMT

The Major Alteration and Addition Ordinance

In 2018, City Council updated the rules for major residential alterations and additions. We refer to these as MRAAs. The guidance on this page follows those rules.

Learn more about the Portland City Code for Major Residential Alterations and Additions ↗.

You can find more specifics in the permanent administrative rule for demolitions ↗.

When major alteration and addition requirements apply

MRAA requirements apply to residential structures that have a residential Comprehensive Map Designation. They do not apply to properties in commercial areas, including multifamily residences. Check your property on the Zoning and Comprehensive Plan Maps ↗. In most cases, the Comprehensive Plan designation is the same as the zoning for a property.

Projects exempt from the MRAA ordinance:

Non-habitable accessory structures, such as detached garages. This kind of project is not an MRAA, even if you're converting it to habitable space as a result of the remodel.
- NOTE: An attached garage is considered part of the main house. If your project involves an attached garage, its walls and size count toward the MRAA limits.
Conversions ↗ that don’t remove exterior walls or expand the structure’s footprint or structural barrier. This is true even if your project adds over 500 square feet of habitable space.
Detached accessory dwelling units (ADUs) ↗. The ordinance does not apply to new construction of detached ADUs ↗.

Permits needed for an MRAA

You'll need a building permit ↗ for a major residential alteration or addition.

You'll likely need trade permits ↗ (electrical, mechanical, and plumbing).

What qualifies as a major alteration or addition?

The ordinance defines a major alteration as:

Removing more than 50% of the exterior walls above the foundation. To calculate this, we include any exterior wall above the foundation. Our calculations are in linear feet by story.

The ordinance defines a major addition as:

Adding more than 500 square feet of new interior space that expands the structure’s footprint or envelope. New interior space does not include existing space within the building envelope. Major additions must increase the interior space and expand the footprint or envelope.

For more information about what qualifies as an MRAA

Get information on MRAA definitions, examples, instructions, and more:

Download and save a copy of this Life Safety completeness checklist: