Generally speaking, only one home (i.e. one principal structure) is permitted per parcel (an "over-and-under" style duplex is considered one principal structure). For a parcel with an existing single-family dwelling, one additional home known as an accessory apartment may be permitted. An accessory apartment must be smaller than the existing home as measured in gross square footage. Gross square footage is measured from the exterior walls and includes all area within. For any bona fide farm, up to seven additional homes may be permitted for farm tenants, managers, and similar employees. The property owner must certify, via an affidavit supplied by the county, that a tenant house is not being built to circumvent county law.