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.  

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. 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 PortlandMaps.com), 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 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.

4. 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.

5. 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.

6. 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

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

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.

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.

The Bureau of Development Services sells a "Residential Combination" permit package. This allows you to call for all inspections using just the Building Permit (RS) IVR number and pay for all the permits at one time. You will need to submit the trade (mechanical, electrical, and/or plumbing) application(s) signed either by you, if you are doing these portions of the work yourself, or by your licensed subcontractors. If you do not have your completed subcontractor forms when you are applying for your residential permit (RS) you will have to apply for trade permits separately from the building permit. Sub-contractors that you hire must be registered with the State of Oregon and carry the correct licenses in association with their trade.

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.

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 met.

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


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