Special development standards apply to the number, size and placement of detached accessory structures. Section 09.10.20 of the Zoning Ordinance sets permit requirements and explains exceptions.
For example, on lots of one acre or less, when the principal use of a lot is a one-family dwelling, approval of a Site Development Permit is required to allow:
One accessory building (e.g. shed, barn, guest quarters) with a total floor area of up to 650 square feet, or 2) one additional detached accessory building with a floor area of 120 square feet or larger on a lot which already has one or more existing or approved detached accessory buildings with a floor area of 120 square feet or larger. Detached accessory structures with floor areas of less than 120 square feet do not require permits.