Enlarging the Building Footprint
Table of Contents
Building permits are required for building an addition to a single-family dwelling. This includes enclosing a porch and adding new living space to your home by enlarging the footprint of the original building. Depending on the scope of work, your project may also require electrical, plumbing or mechanical permits.
View more information if your project will also involve the addition of a garage.
Your permit will be reviewed under provisions of the current Oregon Residential Specialty Code.
It is recommended to visit or call the Planning and Zoning staff (503) 823-7526 and Buildings staff (503) 823-7310 at the Development Services Center early in the planning of your project.
The following information must be submitted when applying for a permit to enlarge the footprint of a structure. Since every project is unique, there may be some situations where you will be asked to provide additional information.
|Site Plan (Scale site plans to most appropriate scale, e.g. 1”=10’ or 1/4”=1’)
- Property lines, with dimensions
- Total area (in square feet) of the lot
- Adjacent streets and any easements
- Property address and R number
- North arrow
- Grade elevations at property corners and corners of structure(s)
- Distance between buildings and between buildings and property lines
- Area (in square feet) of any existing or proposed buildings
- Area (in square feet) of any proposed paving
- Location of sewer and water lines and method of stormwater disposal
- Major geographical features (e.g. flood plain, natural drainage courses with elevation and centerline)
- Location of existing septic tanks, cesspools and drainfields
|Architectural Plans (Scale of plans to be ¼”=1’ and details scaled to ½”=1’. Single line drawings are not acceptable – plans must be drawn to show wall thickness)
- Fully dimensioned floor plans (including existing and proposed walls, window/door sizes and locations) of each floor affected
- Use of each room
- Plumbing fixture layout
- All exterior building elevations affected by the addition
- Building sections showing typical wall, floor, ceiling, roof and foundation
- Stair details with dimensions for risers, treads and handrails
- Insulation R value for ceiling, walls and floors
- Gas/oil furnace and water heater location
- Electrical light fixtures, smoke detectors and fans
- Details of all non-typical construction
|Structural Plans (Scale of plans to be ¼”=1’, details to be ½”=1’)
To submit for a permit, bring the completed building permit application, related materials, and four (4) copies of site, architectural and structural plans (for the area of proposed work and areas affected by such work) along with intake fees to the Development Services Center.
- Foundation plan including ventilation, underfloor access and holdowns
- Cross sections showing framing members, insulation, blocking, materials and floor to floor dimensions
- Floor framing including member size, spacing and span
- Roof framing including member size, spacing and span
- Prescriptive wall bracing floor plans (not required if structure is engineered)
- Any engineering calculations may be attached to the plans and engineering details incorporated into the plans or cross-referenced on the plans
- Prescriptive wall bracing worksheets (not required if structure is engineered)
- Connections to existing construction
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.
|THINGS TO CONSIDER:
(1) Adding an Attached Garage
The City of Portland Title 24.45 (Parking and Driveway Surfaces) requires that vehicle maneuvering areas for a new garage be accessed via a driveway. If you don’t currently have a driveway, you will be required to install a new one. The driveway will need to be paved if it is within 150’ of an improved public right-of-way. For additional information on paving surfaces, see Portland City Code, Title 24.45.020.
If your project requires construction in the public right-of-way, the Portland Department of Transportation will review the project and issue a separate transportation permit for this work. For more information about right-of-way requirements, contact the Portland Department of Transportation at (503) 823-7002.
If your new garage is attached to within six feet of the house, or attached by way of a breezeway, then the interior walls of the garage must be covered with a layer of ½” gypsum board for additional fire protection. Any openings (such as doors and windows) within this distance may be required to be protected, depending on the configuration.
|(2) Residential Engineering
Your project must be designed to meet all the requirements of the building code. This usually means that a full foundation with footings to the frost depth, and a complete lateral force resisting system are required.
The building code has two options for showing the building will resist lateral loads. More information on residential engineering.
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 Dormer Additions.
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.
After you pay intake fees, your project will be "under review". Plan reviewers from the Bureau of Development Services representing fire life safety and structural disciplines, Parks Bureau, Office of Transportation, Bureau of Environmental Services, Water Bureau, and Fire Bureau will all participate in review of your plans.
The bureaus/review groups that will check a typical enlarging the footprint/addition project are:
- Planning and Zoning Review
- Life Safety Review
- Structural Review
- Site Development Review
- Bureau of Environmental Services
- Portland Department of Transportation
- Urban Forestry Review
Find out how to research your property and where to locate the information in preparation for your permit application.
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 the review will continue.
For more information on checksheets.
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 (4) to have a status report faxed to you or call (503) 823-7357 to have one mailed to you.
When the last technical review is approved, your permit will be pre-issued. You will be contacted when your permit is ready, and of your final fee total. Fees may be paid by cash, check, Visa or Mastercard.
If your permit is ready for issuance, you may pick up your permit between 8:00 am - 3:00 pm, Monday-Friday at Permitting Services, located on the 2nd floor of 1900 SW 4th Avenue, Portland, OR. For more information call (503) 823-7357.
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.