Department of Planning and Development Alert:
An accessory living unit is a secondary dwelling unit established in conjunction with and clearly subordinate to a single-family detached dwelling unit. These living spaces include areas for eating, sleeping, living, and sanitation. Accessory living units within the principal dwelling (not in a detached structure) and that meet all of the applicable standards, including access and entrances, size, and parking, may apply for approval through an administrative permit. Otherwise, an accessory living unit requires submission of an application for a special permit, which requires approval by the Board of Zoning Appeals. ALUs that were previously approved by special permit can be renewed through the PLUS system by requesting a Time Extension of Approved Zoning Cases.
All accessory living unit (administrative permit) applications must be submitted electronically through the PLUS application portal.
For additional information on how to use the PLUS application portal, please visit the DPD PLUS Information & Support page. Instructional videos are available on the Fairfax County PLUS - YouTube channel.
If you have technical questions (e.g. account setup, password issues) regarding the PLUS system, please contact the Help Desk:
Property Plan: A plat showing the location of the dwelling. The plat must demonstrate that a total of three parking spaces are provided if the dwelling is located on a public street, and a total of four parking spaces are provided if located on a private street. Please label the location and provide the dimensions of these spaces. The identified spaces must be maintained as available for parking. For example, if the garage is identified, it cannot be used for storage.
Floor Plan: Must depict the internal layout of the principal dwelling and the accessory living unit. Label each room with its use and square footage and identify all existing and proposed external entrances and the internal access between the accessory living unit and the principal dwelling. (Floor plan does not need to be drawn by a licensed professional)
Property Owner Permission Letter: The property owner must live on the application property. If an authorized agent is applying on behalf of the property owner, a signed and dated letter of permission from the property owner must be submitted. The letter must include the address of the of the property, the property owner’s contact information, and a certification that the property owner will live on the property. This document is only required if the applicant is not the property owner.
Interior photos: Must show all rooms and areas that will be included in the accessory living unit. Please label and date each photo. This document is only required if the dwelling is existing.
Exterior photos: Must show all exterior sides of the dwelling and all parking spaces. Please label and date each photo. This document is only required if the dwelling is existing. Proposed elevations may be requested if the ALU involves a new addition.
Land Records Documentation: Provide documentation demonstrating that a copy of the previously approved administrative permit or special permit was recorded in the land records of Fairfax County. This document is only required if the application is a renewal request.
Supporting Documentation (optional): Any additional documentation that supports the request.
As part of the application process, you must agree to abide by the standards found in subsection 4102.7.B and 4102.1.I of the Zoning Ordinance, as described below:
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).
(1) The County may inspect the property during reasonable hours and in accordance with subsection 8106.2.D.
(2) The Zoning Administrator may revoke an administrative permit at any time if the owner or operator of the use fails to comply with all requirements of the law with respect to maintenance and conduct of the use and all conditions imposed by the Zoning Administrator in connection with the permit.
(3) The Zoning Administrator will issue a notice of revocation to the owner or operator, hand-delivered or mailed, return receipt requested, setting forth the grounds upon which the permit was revoked, the date and time the revocation took effect, and describing the appeals procedure. Upon receipt of the notice, operation of the activity must cease.
(4) These provisions do not preclude the use of any other remedy prescribed by law or by this Ordinance with respect to violations of this Ordinance.
Summary of the Adopted Accessory Living Unit Provisions
Accessory Living Unit Frequently Asked Questions
Fire Alarm Installation Certification
For additional assistance, please contact the Zoning Permits Section by phone at 703-222-1082 or by email.