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Development Services

From Concept to Construction

Phone: 503-823-7300


1900 SW 4th Ave, Portland, OR 97201

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Dormer or Second Floor Additions

Information on adding onto your house or duplex, when the scope includes expanding the upper story or attic outside of the existing roof or envelope.

Getting Started

A building permit is required for any addition to a single-family dwelling. Any project that changes the building envelope such as building a dormer or a new second story is considered an addition. Depending on the scope of work, your project will most likely require electrical, plumbing and/or mechanical permits.

Your permit will be reviewed for compliance with the Portland Zoning Code, the Building Code and other local regulations.

  • Applicable City and State Codes: Refer to the Codes page on the Bureau of Development Services (BDS) website.
  • Portland’s applicable building code is the Oregon Residential Specialty Code. See the State Codes page for more information about this and other construction codes in effect.
  • The Portland Zoning Code, (City Title 33) includes use regulations and development standards, such as maximum building footprint coverage and setbacks, and can be found on the Zoning Code page.

General Information

Our "New Users" tab is a good place to start for overall information about the permitting process.

Things to Consider when Planning your Project

1. Researching Building Permit Records for Your House
Before preparing building permit plans, it is important to verify that existing finished space in your house was legally permitted. BDS maintains building permit records that can help you prepare plans for your current house project. Historical inspection cards or microfilmed permit plans may be available to determine the existing “permitted” condition of your house. Although the Multnomah County Assessor maintains information about your house’s living area (available on, this information may not match the building permit history. There is no "grandfathering-in" of unpermitted finished or living areas, and to be considered legal living area, a permit is required.

2. Major Alterations and Additions
Projects that add square footage or height to an existing house or duplex may qualify as “Major Additions” depending on the size of the addition and scope of work relative to the existing structure. These types of permits have additional requirements for notification of the neighboring properties and neighborhood association. There is a waiting period between the time of notification and when the permit can be issued, so it is important to plan ahead.

(3) Included Work, such as Enlarging the Footprint
This page covers projects that expand the house vertically by adding a dormer or second floor.  If your project will include other types of work, such as enlarging the footprint or adding a garage, please see those information pages for additional requirements.

Please refer to the Residential Permits summary page for more information.

(4) Evaluating Existing Space
In unfinished areas, existing features such as ceiling heights, windows, stairs and insulation may not meet current Building Code requirements for finished space. These conditions could make it expensive, difficult or even impossible for you to change your attic into living space. It is best to complete your research on the existing conditions before submitting plans for review. Habitable space standards for existing space are explained in Brochure 9, “Converting Attics, Basements and Garages to Living Space”.

(5) Attic Conversions
You must determine if the existing attic floor structure is strong enough to carry the weight of people and furniture.

If converting attic space to living space would mean raising the roof, the Zoning Code height regulations may affect your project. 

(6) Residential Engineering
Your project must be designed to meet all structural requirements in the Building Code. The construction drawings must show how both gravity and lateral (wind and earthquake) loads will be resisted.  Please see our page on Residential Engineering for more information on these requirements.

Note that plans and calculations will not be required to show that a structure will resist wind and earthquake loads if it can be considered a "minor" addition. See Lateral Bracing for Minor Additions and Dormers. Please note that a “minor” dormer for the purpose of determining lateral bracing requirements may still be subject to the requirements of a “major addition” per City Code Chapter 24.55 (see item 2, above).

When the scope of work will change the structural load in the house, it is important that you submit engineering calculations that show the continuity of the load path from floors or other affected members all the way to the foundation of the house. It is very common that when tracing floor loads from the converted attic, it is the beam in the basement that will be overstressed. Situations like this are required to be resolved as part of the permit application. 

(7) Floodplains
If your house is located in a floodplain, there are restrictions that may limit your ability to add to or significantly improve your house without retrofitting it to be flood-resistant. Please contact Site Development staff at (503) 823-6892 to discuss your project.

Permit Fees
Permit fees are based on the fair market value of the work included in the permit.

Applying For My Permit

The following information must be submitted when applying for a permit to add a dormer or second floor to an existing one or two family dwelling. Since every project is unique, there may be some situations where you will be asked to provide additional information.

Additional required materials depending on the scope of work, or specific site conditions:

To submit for a permit, bring the above materials along with intake fees to the Development Services Center.

If you are hiring sub-contractors to do work on your project, and know who they are when applying, they will be listed on your permit at that time. If you don't know when you apply for your permit, they can be added after issuance. Sub-contractors you hire must be registered with the State of Oregon and carry a current CCB license.

Plan Review Process

Some simple permits can be reviewed and issued "over the counter” in the Development Services Center.  You will meet individually with city staff from different departments.  Each staff person will review your plans with you to verify that the proposed construction meets requirements. If information is missing or if corrections are needed, you will be asked to update your plans. In this case, another trip to the Permit Center may be needed.

If the project is more complex and a review cannot be completed over the counter, the plans will be taken in for further review. You will be sent a checksheet requesting any clarifications or corrections. For additional information on the review process, see the permitting process overview flowchart.

Neighborhood Notification for Major Additions
If your project qualifies as a Major Addition, then the required notification delay can overlap with the time the permit is being reviewed; however, the permit cannot be issued until 35 days after the neighborhood notification requirements have been completed.

The bureaus/review groups that will check your project vary depending on the scope of work and may include:

  • Planning and Zoning Review
  • Life Safety Review
  • Structural Review
  • Site Development Review
  • Urban Forestry Review
  • Water Bureau

A checksheet is sent to the applicant when a reviewer needs additional information or a correction has to be made to the plans. When you have gathered the additional information or made the corrections, bring the plans/information to the Development Services Center. Reviewers will be notified that a checksheet response has been received and review will continue.

More information on checksheets

Status Reports
Status reports are available after your project has been assigned to reviewers. Status reports show all reviews and include the reviewer’s name and phone number. To obtain a status report, call (503) 823-7000 and select option four to have a status report faxed to you or call (503) 823-7357 to have one mailed to you.

Permit Issued
When the last technical review is approved, your permit will pre-issued. You will be contacted to let you know when your permit is ready, and of your final fee total. Fees may be paid by cash, check, Visa or Mastercard.

When your permit is ready to be issued, you may pick up your permit at Permitting Services, located on the 2nd floor of 1900 SW 4th Avenue, Portland, OR. For more information call (503) 823-7357. For hours, see the hours listed on the Development Services Center page.


The yellow inspection card lists all the inspections you will likely need during your construction project, and what work needs to be done first.

Once your building permit is issued, erosion control measures must be installed, prior to beginning any further ground disturbing activities.

Applications & Handouts