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Development Services

From Concept to Construction

Phone: 503-823-7300

TTY : 503-823-6868

1900 SW 4th Ave, Portland, OR 97201

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.

Table of Contents

(Printable Version)

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 under provisions of the current Oregon Residential Specialty Code. View more information on building codes.

 

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.

 

Checking your House’s History

Depending on the age of your house, we may have permit cards or microfilm on file that will show the history of permit activity for your house. It is important to verify that the “existing” finished attic or basement was permitted as such in the permit records, and not just through the county assessor’s office. Information found on http://www.portlandmaps.com/ is reported from the county's assessor's office, and may not match the building permit history. There is no grandfathering-in of these spaces, and to be considered living space, they would need to be legalized through the permit process.

 


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.

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
  • Distance between buildings and between buildings and property lines
  • Dimensions and area (in square feet) of any proposed paving. (If your project will add more than 500 square feet of impervious area you will need to provide a mitigation form and/or a stormwater plan).
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 locations) for 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’)
  • Foundation detail showing existing foundation wall thickness and footing size
  • 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
To submit for a permit, bring the completed building permit application 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.
 
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 will carry a current CCB license.
 
Things to consider:
Note: To make conversions easier, the Bureau of Development Services has set up the following special standards for existing situations:
  • Ceiling height in basements, attics and bathrooms
  • Stairs
  • Emergency Egress Windows
  • Insulation and Ventilation
(1) 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.
 
(2) 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. 
 
(3) 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 Additions and Dormers.

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. 
 
(4) Floodplains

If your house is located in a floodplain, the ability to do these types of improvements may be severely limited. Please contact Site Development staff at (503) 823-6892 to discuss your project.

 


Plan Review Process

After you pay intake fees, your project will be "under review". The bureaus/review groups that will check a typical conversion project are:

  • Planning and Zoning Review
  • Life Safety Review
  • Structural Review
  • Site Development Review
  • Urban Forestry Review
Overview of the permitting process
 
Checksheets
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 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.  

Inspections

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

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