Skip to Main Content View Text-Only

Development Services

From Concept to Construction

Phone: 503-823-7300


1900 SW 4th Ave, Portland, OR 97201

More Contact Info

Enlarging the Building Footprint

Getting Started

Any project that enlarges the footprint of an existing building requires a building permit. Enclosing a porch or adding new living space to your house are examples of projects that require a building permit. Depending on the scope of work, electrical, plumbing or mechanical permits may also be required.

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

  • Applicable Cityand 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.

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. The 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.

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 this kind of permit. Since every project is unique, there may be some situations where you will be asked to provide additional information.

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 ofOregonand carry a current CCB license.


(1) Included work, such as an Attached Garage or Additional Floor

If your project will include the addition of a garage, please also see our page on Garage, Shed and Accessory Structures for special requirements.

Additional requirements may apply if the scope of work includes converting existing unfinished space to living space, or adding a dormer or additional floor to the house. Please refer to the summary page for more information.

(2) 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.

(3) 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.

(4) Decommissioning a Septic Tank or Cesspool

When enlarging the footprint of an existing structure, septic tank/cesspools must be located and shown on the site plan.

  • Visit the records staff at the Development Services Center to research plumbing records showing septic systems/cesspools
  • If the septic system/cesspool has been decommissioned, and is within 10 feet of the new structure, you must sign a disclaimer for on-site-sewage disposal system form
  • If the septic system/cesspool is within 10 feet of the new structure and has not been pumped and filled, it will need to be decommissioned

Call Environmental Soils staff at (503) 823-6892 for more information on decommissioning septic tanks and cesspools.

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 thePermitCenter 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.

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

  • Planning and Zoning
  • Life Safety
  • Structural
  • Site Development Review
  • Bureau of Environmental Services Review
  • Bureau of Transportation
  • Urban Forestry Review
  • Water Bureau


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