Chapter 18.154
ACCESSORY DWELLING UNITS
Sections:
18.154.040 Building requirements.
18.154.060 Standards for attached ADUs.
18.154.070 Standards for detached ADUs.
18.154.080 Conditional use hearings.
18.154.090 Existing illegal ADUs.
18.154.010 Purpose.
The city planner shall have the authority to approve attached accessory dwelling units (ADUs) which are consistent with single-family neighborhood character and the regulations and provisions herein. The planning commission shall have the authority to approve detached accessory dwelling units which are consistent with single-family neighborhood character and the regulations and provisions herein. It is not the intent of these regulations to provide for ADUs on every residential property and they shall not be deemed to create a right or privilege to establish or maintain an ADU which is not strictly in compliance with these regulations. (Ord. 1095 § 2, 2024)
18.154.020 Requirements.
ADUs may be permitted in residential districts suburban residential (S-R), low density residential (R-1) and medium density residential (R-2) as accessory to single-family dwellings, subject to the requirements that follow. (Ord. 1095 § 2, 2024)
18.154.030 Site requirements.
A. A certification from the public works superintendent that existing water and sewer facilities serving the property are adequate is required.
B. Only one ADU shall be permitted (attached or detached) as accessory to a single-family dwelling unit.
C. An accessory dwelling unit may not be sold as a separate piece of property, or as a condominium unit, unless allowed by the existing zoning on the property.
D. Parking. A minimum of two existing off-street parking spaces must be provided on the property where an ADU is proposed; one additional parking space for the ADU is required.
1. “On-street parking” is defined as parking spaces legally available for parking of vehicles. Posted time- or day-restricted parking spaces are not considered as available for purposes of this section.
2. A street/sidewalk entrance in the form of a walkway, landscaping features, mailbox post and similar construction to direct visitors to the ADU, is required per the determination of the city planner upon recommendation by the fire marshal.
E. Fire department access shall extend to within 150 feet of all portions of the exterior walls of the building as measured by an approved route. Distances in excess of 150 feet may result in additional requirements for construction as approved by the fire code official. Alleys shall not be considered for fire department access. (Ord. 1095 § 2, 2024)
18.154.040 Building requirements.
A. Accessory dwelling units must be on the same lot as the single-family dwelling to which they are accessory. They may be attached (added to or created within) the existing single-family dwelling as provided for in RMC 18.154.060, or detached as provided for in RMC 18.154.070.
B. All housing and building codes and standards shall be applicable to all ADUs including, but not limited to, the building code, the plumbing code, the electrical code, the mechanical code, the fire code, and all requirements of the Columbia County health department. Note: manufactured homes may be used for ADUs but must be less than 10 years old.
C. Detached ADUs shall have separate independent utility connections and solid waste facilities.
D. The square foot area of any ADU, excluding any garage area, shall be not less than 300 square feet nor in excess of 1,000 square feet, and it shall contain no more than two bedrooms.
E. Street-facing entrances may be allowed. Exterior entrances can be located no closer than 10 feet to an adjoining private property line.
F. Any exterior stairs shall be placed in the rear or side yard and no closer than 10 feet to an adjoining private property line.
G. All ADUs shall have separate street addresses that are visible from both the street and alley that clearly identify the location of the ADU. (Ord. 1095 § 2, 2024)
18.154.050 Occupancy.
A. The owner of the property or immediate family member of the property owner, or contract purchaser of record, of the single-family dwelling to which an ADU is accessory, shall reside either in the single-family dwelling or the ADU as a permanent place of residence (must occupy one of the dwelling units on the property for more than six months of each calendar year).
B. Only one of the residences may be rented or leased.
C. Vacation (short-term) rental, transient accommodation, and/or lodging is prohibited in ADUs or in single-family dwellings to which they are accessory. “Vacation (short-term) rental, transient accommodation and/or lodging” means the rental of any building or portion thereof used for the purpose of providing lodging for periods of less than 30 days.
D. The ownership of ADUs may not be separated from ownership of the single-family dwelling to which they are accessory.
E. Before issuance of the certificate of occupancy for an accessory dwelling unit, the homeowner must provide a copy of a statement recorded with the Columbia County clerk.
1. The statement must read:
An application for a permit for an accessory dwelling unit has been submitted to the city of Rainier by the owner of this property. Future owners are advised that the owner of the property must comply with all requirements of the Rainier Zoning Code, as amended, if the accessory dwelling unit is to be occupied or rented.
2. If an accessory dwelling unit is to be removed, appropriate permits and inspections must first be received from the city and Columbia County. If a homeowner wants to remove the statement as required by subsection (E)(1) of this section from the property’s title, then the city shall issue an appropriate release upon evidence that the accessory dwelling unit has been removed. The release shall be recorded by the homeowner with the county clerk’s office and a copy of the recorded release shall be provided to the city.
F. No day care centers or adult family homes shall be permitted in ADUs.
G. The following permit and inspection requirements shall be met:
1. No ADU may be added to, created within, or constructed upon the same lot as a single-family dwelling without a permit having been issued by the Columbia County land development services department;
2. All applications for ADU permits shall be on forms provided by the city recorder, and the fee for such permit shall be as provided in the building code;
3. No ADU may be occupied unless the owner of record of the single-family dwelling to which it is accessory possesses a current certificate of occupancy for such ADU;
4. Before any permit for the creation or construction of an ADU is granted, the proposed site thereof and the plans and specifications therefor shall be inspected by the building and fire officials to ensure that the provisions of this chapter are not violated; and
5. The building official may inspect ADUs after giving proper notice, at such time as a complaint alleging noncompliance with this chapter is received by the city. The purpose of such inspection shall be to determine if such ADU is in compliance with the requirements of this chapter. If such inspection reveals that such ADU is in compliance, the building official shall issue a certificate of occupancy for said ADU. If the inspection reveals the ADU is not in compliance, the building official shall not issue a certificate of occupancy for said ADU, and shall notify the owner or contract purchaser of the single-family dwelling to which said ADU is accessory that said ADU must be vacated and not occupied until it is reinspected by the building official and found to be in compliance, or the ADU removed. (Ord. 1095 § 2, 2024)
18.154.060 Standards for attached ADUs.
A. All attached ADUs shall be designed to maintain the appearance of the single-family dwelling to which they are accessory. If an ADU extends beyond the current footprint of the single-family dwelling, it must be consistent with the existing siding of the single-family dwelling. Any additions to an existing structure or building shall not exceed the allowable lot coverage or encroach into the required setbacks.
B. When garage space is converted to accessory dwelling unit living space the portion of the driveway leading to the former garage may remain. The parking standards identified above will still apply. (Ord. 1095 § 2, 2024)
18.154.070 Standards for detached ADUs.
In the event that the planning commission grants a conditional use permit for the construction of a detached ADU (i.e., an ADU that is not added to or created within the single-family dwelling) in accordance with this chapter, all of the provisions of this chapter shall be applicable thereto. In addition, the following provisions shall be applicable to such detached ADUs:
A. Landscaping may be provided for the privacy and screening of adjacent properties. Tall vegetative landscaping may be required between any windows or decks facing adjacent residential properties.
B. Two-story, detached accessory dwelling units may be designed to protect the privacy of adjacent residential uses.
C. Detached accessory dwelling units are not permitted in townhouse, zero lot line detached housing, or attached zero lot line housing developments. (Ord. 1095 § 2, 2024)
18.154.080 Conditional use hearings.
A. All proposed detached ADUs shall require that a conditional use permit be granted by the planning commission via a Type III review process with consideration of impacts to privacy of neighboring properties. Where practical, the ADU should be located and designed to minimize disruption of privacy and outdoor activities on adjacent properties. Strategies to accomplish this include, but are not limited to: window staggering, entries facing away, no overlooking decks, and landscaping.
B. In its consideration of an application, the planning commission shall evaluate:
1. Compliance with this section.
2. Window locations.
3. Impacts from shading of neighboring properties, specifically solar access and impacts to existing solar collection systems, photovoltaic or solar heating. (Ord. 1095 § 2, 2024)
18.154.090 Existing illegal ADUs.
A. Application may be made for any accessory dwelling unit existing prior to the effective date of this chapter to become legally permitted, pursuant to the provisions of this chapter.
B. An application to legalize an existing ADU shall include an application for an ADU permit and a building permit application showing changes made to the main residence or detached accessory building to accommodate the ADU. Approval shall be consistent with the ADU regulations and process outlined in this section. The ADU shall be reviewed using the current editions of building codes in place at the time its owner brings the unit forward for permit.
C. Nothing in this section shall require that the city permit existing ADUs that are determined to be noncompliant with this chapter. (Ord. 1095 § 2, 2024)