Springfield, OR Accessory Structures: Garage Conversions (2026)

Springfield Development Code section 3.2.275(B)(1) names converting a garage, attic, basement, or other portion of the existing house as the first of four recognized ways to create an accessory dwelling unit, alongside adding floor area, building a new detached unit, or converting an existing small dwelling. A garage conversion is treated as a conversion for design purposes: section 3.2.275(G) states that conversion of a structure to an accessory dwelling unit is not required to meet the design standards and may be approved under a Type 1 procedure, the same streamlined review used for most ADUs.

That exemption only covers exterior design matching, things like siding, roof pitch, trim, and window style under section 3.2.275(G)(1); it does not exempt the converted garage from the numeric development standards in section 3.2.275(F). The converted space must still meet every clear and objective standard that applies to the primary dwelling, including setbacks, height and lot coverage, must not exceed 800 square feet or the primary dwelling's own square footage, excluding its garage, whichever is less, must contain a kitchen, bathroom and sleeping area fully independent from the house, and must gain its own separate entrance and its own address.

If the garage conversion does require an exterior alteration to meet current building or fire code, that specific alteration still has to satisfy the applicable design standard, either matching the primary dwelling's materials or meeting the code's alternative clear-and-objective design standards under section 3.2.275(G).