Standards when permitted by administrative permit:
(1) An accessory living unit is permitted only in association with a single-family detached dwelling unit, and no more than one accessory living unit is permitted on a single-family lot.
(2) An accessory living unit must be wholly contained within the structure of a single-family detached dwelling unit and must have direct access to the principal dwelling through an interior space that is finished, temperature controlled, and fully enclosed.
(3) Any new external entrance proposed for an accessory living unit must be located on the side or rear of the dwelling. Any proposed garage or carport must be located directly adjacent to any existing garage or carport, and the associated driveway and curb cut must be the same as that which serves the principal dwelling.
(4) The accessory living unit must not exceed:
(a) 800 square feet of gross floor area or 40% of the gross floor area of the principal dwelling, whichever is less; or
(b) the entirety of the basement or cellar may be used, up to the size of the basement or cellar as of July 1, 2021. A larger size may be allowed by special permit in accordance with subsection 8100.4. For the purpose of determining the size of an accessory living unit approved either by administrative permit or special permit, regardless of the definition in Article 9, gross floor area includes the area of any basement or cellar having a structural headroom of six feet six inches or more, but does not include a garage.
(5) The accessory living unit may not contain more than two bedrooms.
(6) Either the accessory living unit or the principal dwelling unit must be owner-occupied.
(7) The accessory living unit may be occupied by no more than two people.
(8) The principal single-family dwelling unit may be occupied by not more than one of the following:
(a) Two or more persons related by blood or marriage and any number of their natural children, foster children, stepchildren, adopted children, or children in kinship care;
(b) One or two persons with their dependent children, including natural children, foster children, stepchildren, adopted children, or children in kinship care, functioning as a single household; or
(c) A group of not more than four persons not related by blood or marriage, functioning as a single household.
(9) As specified in Article 6, a dwelling with an accessory living unit must provide the number of on-site parking spaces required for the principal dwelling unit, plus one additional space. Only one space serving the lot must provide convenient access to the street.
(10) An accessory living unit must meet all applicable regulations for building, safety, health, and sanitation, and the construction of an accessory living unit is not deemed to be a subdivision of the lot on which the dwelling is located. If the dwelling is served by a well or septic system, the applicant must obtain Health Department approval prior to administrative permit or special permit approval.
(11) The accessory living unit must have a working multi-purpose fire extinguisher and smoke and carbon monoxide detectors (when required for a fireplace or gas service) that are interconnected with the principal dwelling.
(12) Before occupancy of the accessory living unit, the owner must record a copy of the administrative permit among the land records of Fairfax County. The permit must contain a description of the property and must be indexed in the Grantor Index in the name of the property owner(s).
(13) An administrative permit for an accessory living unit may be issued to the owner for an initial period of two years from the date of approval. An administrative permit may be extended by the Zoning Administrator for succeeding periods of up to five years based on the applicant’s record of compliance with the standards in this subsection.
(14) If the standards above are no longer being met, the accessory living unit may not be occupied as a dwelling unit and the property must meet the occupancy limitations of a single-family dwelling in accordance with subsection 4102.3.A. This standard does not require the removal of any kitchen or other facilities.
Standards when permitted by special permit:
(15) The accessory living unit must conform to all applicable standards for an administrative permit above, except that the BZA may approve a special permit for an accessory living unit to modify one or more of the standards as identified in the subsections below:
(a) Subsection (2), to permit an accessory living unit in a freestanding structure, but only on a lot of at least two acres;
(b) Subsection (3), to modify the location of any external entrance and access from the street;
(c) Subsection (4)(a), to exceed the maximum size for an interior accessory living unit; and
(d) Subsection (9), when the required on-site parking is not provided.
(16) The area devoted to a detached accessory living unit must not exceed 1,200 square feet of gross floor area and must be clearly subordinate to the principal dwelling.
(17) The BZA may require the provision of off-street parking spaces in addition to the requirements specified in Article 6 for a single-family detached dwelling.
(18) The County may inspect the property during reasonable hours and in accordance with subsection 8106.2.D.
(19) Upon the approval of a special permit, the owner will record a copy of the BZA’s resolution of approval, including all accompanying conditions among the land records of Fairfax County. The resolution must contain a description of the property and must be indexed in the Grantor Index in the name of the property owner(s).
(20) A special permit for an accessory living unit may only be issued to the owner and approved for an initial period of two years from the date of approval. The special permit may be extended for succeeding periods of up to five years based on the applicant’s record of compliance, in accordance with subsection 8100.4.D(3).