Chapter 17.128 AUXILIARY DWELLING UNITS

Chapter 17.128
AUXILIARY DWELLING UNITS

Sections:

17.128.010 Purpose.

17.128.020 Applicability.

17.128.030 Design standards.

17.128.010 Purpose.

Auxiliary dwelling units are allowed in certain situations to:

(1) Create new housing units while respecting the look and scale of single-dwelling neighborhoods;

(2) Increase the housing stock of existing neighborhoods in a manner that is less intense than alternatives;

(3) Allow more efficient use of existing housing stock and infrastructure;

(4) Provide a mix of housing that responds to changing household needs, sizes and compositions;

(5) Provide a means for new homeowners to defray some of the costs associated with the purchase of a first home;

(6) Provide a means for residents, particularly seniors, single parents, and families with grown children, to remain in their homes and neighborhoods and obtain extra income, security, companionship and services; and

(7) Provide a broader range of suitable and affordable housing. (Ord. 2875 § 1.158.010, 2003)

17.128.020 Applicability.

An auxiliary dwelling unit may be added to a house, attached house, or manufactured home in any zone where the existing principal use is permitted. (Ord. 2875 § 1.158.020, 2003)

17.128.030 Design standards.

(1) Standards for creating auxiliary dwelling units address the following purposes:

(a) Ensure that auxiliary dwelling units are compatible with the desired character and livability of St. Helens residential zones;

(b) Respect the general building scale and placement of structures to allow sharing of common space on the lot, such as driveways and yards;

(d) Provide adequate flexibility to site buildings so that they fit the topography of sites; and

(e) The design standards for auxiliary dwelling units are stated above. If not addressed in this section, the base zone development standards apply.

(2) Requirements for All Auxiliary Dwelling Units. All auxiliary dwelling units must meet the following standards:

(a) Creation. An auxiliary dwelling unit may only be created through the following methods:

(i) Converting existing living area, attic, basement or garage;

(ii) Adding floor area;

(iii) Constructing a detached auxiliary dwelling unit on a developed site; or

(iv) Constructing a new house, attached house, or manufactured home with an internal or detached auxiliary dwelling unit;

(b) Entrances. Only one entrance to the house may be located on the front facade of the house, attached house, or manufactured home facing the street, unless the house, attached house, or manufactured home contained additional front door entrances before the conversion to an auxiliary dwelling unit was created. An exception to this regulation is entrances that do not have access from the ground, such as entrances from balconies or decks;

(d) Heated Floor Area. The heated floor area of the auxiliary dwelling shall be 100 percent of the floor area of the auxiliary dwelling unit;

(e) Parking. The parking requirements balance the need to provide adequate parking with maintaining the character of single-dwelling neighborhoods and reducing the amount of impervious surface on a site. More parking is required when a vacant lot is being developed because, generally, the site can more easily be designed to accommodate two parking spaces while minimizing impervious surface. In situations where an auxiliary dwelling unit is being added to a site with an existing dwelling unit, it is appropriate to not require additional impervious surface if adequate on-street parking is available:

(i) The following parking requirements apply to auxiliary dwelling units:

(A) No Additional Parking Space Required. No additional parking space is required for the auxiliary dwelling unit if it is created on a site with an existing house, attached house, or manufactured home and the roadway of at least one abutting street is at least 20 feet wide;

(B) One Additional Parking Space Required. One additional parking space is required for the auxiliary dwelling unit as follows:

1. When none of the roadways in abutting streets are at least 20 feet wide; or

2. When the auxiliary dwelling unit is created at the same time as the house, attached house, or manufactured home.

(f) Size.

(i) Minimum Size. The size of the auxiliary dwelling unit may be no less than 220 square feet;

(ii) Maximum Size. The size of the auxiliary dwelling unit may be no more than 30 percent of the living area of the house, attached house, or manufactured home or 1,000 square feet, whichever is less.

(3) Additional requirements for detached auxiliary dwelling units or for auxiliary dwelling units created through the addition of floor area:

(a) Exterior Finish Materials. The exterior finish material must be the same, or visually match in type, size and placement, the exterior finish material of the house, attached house, or manufactured home;

(b) Roof Pitch. The roof pitch must be the same as the predominant roof pitch of the house, attached house, or manufactured home;

(c) Trim. Trim on edges of elements on the addition or detached unit must be the same in type, size, and location as the trim used on the rest of the house, attached house, or manufactured home;

(d) Windows. Windows must match those in the house, attached house, or manufactured home in proportion (relationship of width to height) and orientation (horizontal or vertical);

(e) Eaves. Eaves must project from the building walls the same distance as the eaves on the rest of the house, attached house, or manufactured home;

(f) Setbacks. The auxiliary dwelling unit must meet the same setback requirements as principal dwelling units in the zone;

(g) Lot Coverage. The detached auxiliary dwelling unit may not have a larger footprint than the footprint of the house, attached house, or manufactured home, and the combined footprint of all detached structures may not exceed the lot coverage restriction of the zone. (Ord. 2875 § 1.158.030, 2003)