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| Pre-Application Inspection |
| Prior to applying for a permit to create an ADU within an existing house, the applicant must request an inspection of the existing structure. The inspector will complete an inspection report noting any necessary corrections.
A pre-application inspection is not required where the ADU is being created as part of a new building, by an addition to a house or in an accessory building.
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| The following information must be submitted when applying for a permit to build an ADU. Since every project is unique, there may be some situations where you will be asked to provide additional information.
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| 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
- Dimensions and area (in square feet) of any existing or 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
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| 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 (normally three sides required)
- North arrow
- 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
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| Structural Plans (Scale of plans to be ¼”=1’, details to be ½”=1’) |
- Foundation plan including ventilation, underfloor access and hold-downs
- Cross sections showing framing members, insulation, blocking, materials and floor to floor dimensions
- Floor framing including lumber size, spacing and span
- Roof framing including lumber size, spacing and span
- Braced wall panel locations shown on appropriate plans (BP/ABP per OTFDC or engineered calculations)
- Any engineering calculations may be attached to the plans and engineering details incorporated into the plans or cross-referenced on the plans
- Connections to existing construction
To submit for a permit, bring the completed NSFR Intake Packet if proposing a Detached ADU, a building permit application form, the requested inspection report, a completed residential system development charge form, 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 carry a current CCB license.
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| Things to consider: |
| (1) Converting to a Duplex |
| 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, basement or garage into living space.
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| (2) Design Standards |
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There are a variety of design and use standards which apply to the creation of an ADU. These include limiting the overall number of residents in both units, limitation with respect to home occupations, the location of entrance doors and size of the ADU. Where an ADU is created in a new or existing detached structure or by the addition to a house, there are additional standards regulating the exterior appearance and materials of the ADU. These additional standards include provisions for the height, roof pitch, trim, eaves and windows.
- Size of ADU: The ADU may be no more than 75% of the total living area of the house or a maximum of 800 square feet, whichever is less.
- Entrance Location: Only one entrance can be located on the facade facing a street. If an existing building has more than one street facing entrance, then each unit can have a street facing entrance. A secondary entrance to each unit can face a street where there is not access to the ground floor but the door provides access to a balcony or deck.
- Attached vs. Detached: The zoning code standards for attached versus detached ADUs differ as follows:
- Detached buildings. To be considered a detached building, the following conditions must be met:
- Zoning code - The ADU must be at least 60 feet from the front property line, or the ADU must be at least six feet behind the house, attached house or manufactured home.
- Building code - In order to meet fire life safety requirements, all detached ADUs must be separated from the primary building by at least six feet.
- Attached buildings. To be considered attached, living space of both the primary struture and ADU must abut (be on opposite sides of the same wall). Incidental and accessory features such as trellises, decks, patios, breezeways, garages or tool sheds will not be considered as establishing an attached structure.
- Parking: Additional parking is not required for an ADU. However, if parking is required for the existing dwelling unit, that parking must either be retained, or if eliminated in the creation of the ADU, replaced.
- Other Uses: A Type A home occupation can be on the same site as an ADU. Type B home occupations are prohibited from being located on the same site as an ADU. If a Type B home occupation is already located in a house, then a subsequent application for creating an ADU will be denied unless the home occupation is removed.
- Design Review: Design review is required for development of ADUs in a ‘d’ overlay zone, when external modifications to the site or existing house are made. These ADUs must meet the Community Design Standards, where allowed, or, alternatively, be approved through the design review process.
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| (3) Construction Standards |
| The ADU Program Guide outlines the construction standards for ADUs. |
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| (4) Water |
| Regulations require that each separate structure have a separate water service. For more information call the Bureau of Water Works at (503) 823-7368 |
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| (5) Sanitary and Storm Sewers |
| The ADU can either connect to the existing sanitary sewer system or have a separate connection. If a separate connection is made, a sanitation permit is needed for the installation. |
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| (6) Decommissioning a Septic Tank or Cesspool |
| When building an ADU, the septic tank/cesspool must be located (if one exists). |
- Visit the records staff at the Development Services Center to locate any old plumbing records showing a septic system/cesspool
- If the septic system/cesspool is decommissioned, and join ten feet of the new structure, you must sign a disclaimer for on-site-sewage disposal system form
- If the septic system/cesspool is within ten feet of the new structure, it will need to be decommissioned
Call Environmental Soils staff at (503) 823-6892 for more information on decommissioning septic tanks and cesspools. |
| (7) If any ground disturbance, erosion control review and inspection may be required. |
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