The City of Pacifica has adopted Article 4.5 – Accessory Dwelling Units in its Municipal Code.

Summary:

General provisions. The following provisions shall apply to all accessory dwelling units:

(1) An accessory dwelling unit shall not be constructed unless a primary dwelling unit exists on a site and such primary dwelling unit has been constructed lawfully.

(2) A site shall contain no more than one accessory dwelling unit. For purposes of this article, a “second unit,” “granny flat,” “in-law apartment,” or similar structure or improvement permitted and constructed in accordance with applicable laws in effect at the time of its construction shall be considered an “accessory dwelling unit” for all purposes. If an accessory dwelling unit permitted and constructed prior to the effective date of this article does not conform to all standards prescribed in this article, the accessory dwelling unit shall be considered nonconforming but lawful, and shall be subject to the provisions of Section 9-4.453(i) governing nonconforming accessory dwelling units.

(3) An accessory dwelling unit may be constructed between a primary dwelling unit and a site’s front property line, or in any other location on a site, subject to the standards in this article.

(4) An accessory dwelling unit shall become the primary dwelling unit on a site if the original primary dwelling unit is demolished or determined to be uninhabitable, and is not replaced or made habitable within one year of its demolition or the determination that it is uninhabitable.   In such case where an accessory dwelling unit becomes the primary dwelling unit, it shall remain so, and be considered a nonconforming but lawful structure if it fails to comply with any zoning standards applicable to a primary dwelling unit in the underlying zoning district, until such time as a new structure compliant with all zoning standards applicable to a primary dwelling unit in the underlying zoning district, is lawfully constructed or otherwise created on the site.

(5) An applicant for a building permit to construct an accessory dwelling unit shall, at the time an application is filed with the City, be an owner-occupant of the site’s primary dwelling unit and shall provide sufficient proof of occupancy upon request by the City. The site’s owner may at any other time offer for rent either the primary dwelling unit or the accessory dwelling unit. The site’s owner shall be required to reside in the primary dwelling unit as its primary residence at any time while the accessory dwelling unit is occupied by a tenant.  A site’s owner shall not allow occupancy of an accessory dwelling unit by a tenant for any reason, with or without payment of rent, unless the site owner maintains occupancy of the primary dwelling unit as its primary residence.

(6) An accessory dwelling unit may be rented but shall not be used for rentals of terms less than thirty (30) consecutive days.

(7) An accessory dwelling unit shall not be sold separate from the primary dwelling unit.  No subdivision of a site containing an accessory dwelling unit may be approved unless all of the following conditions are met: the lots proposed by the subdivision comply with all applicable development standards of the underlying zoning district for a lot containing a primary dwelling unit, including, without limitation, minimum lot area per dwelling unit and setbacks, or a deviation from the standards is granted; if a condominium subdivision, the zoning designation of the site allows two (2) or more primary dwelling units as a permitted use, or if a conditional use, a use permit is granted prior to or in conjunction with the subdivision; and the accessory dwelling unit on the site complies, or provisions are made to bring the accessory dwelling unit into compliance, with all development standards applicable to a primary dwelling unit in the underlying zoning district, including, without limitation, dwelling unit size, setbacks and off-street parking.

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City Of Pacifica website

City of Pacifica Planning Department