Building and Zoning Topics A-Z

This page functions as an A to Z index of topics.

For official definitions of terms, see the glossary of the Zoning Ordinance and the list of definitions in Chapter 2 of the Building Code (the second chapter of each Building Code book). Note that these two resources include some of the same terms but define them very differently. The context in which you encounter a term may help you determine whether you need a zoning definition or a building one.


  • Abut: To physically touch or border upon; or to share a common property line or border. Unless otherwise expressly stated, this definition does not include lots or parcels on the opposite side of a street.
  • Accessory building: A detached subordinate building, the use of which is clearly incidental to that of the main building or to the use of the land. See the Zoning Ordinance §12.9 .
  • Accessory dwelling: A complete independent dwelling unit, with kitchen and bath, designed, arranged, used or intended for occupancy by not more than three (3) persons for living purposes and meeting the standards of the Zoning Ordinance §12.9.2 . and under the same ownership as the main dwelling on the lot.
  • Accessory homestay: A home occupation in which an owner(s) or a tenant(s) of a dwelling unit, who uses such dwelling unit as his/her primary residence, rents to a lodger, either such dwelling unit, or any portion thereof.
  • Administrative change: Any minor modification of an approved site plan or use permit which complies with the Zoning Ordinance, the intent of the County Board in its approval of the site plan or use permit and the general purpose of the comprehensive plan for the development of the area.
  • Affidavit of permit authorization: Unless the permit holder is the contractor licensed in Virginia for the scope of work on the permit OR the permit holder is the property owner and present for all steps of the permitting process, the party that applies for and/or picks up the permit from the Inspection Services Division will need to have an affidavit of permit authorization.
  • Alley: A public thoroughfare less than 30 feet wide that is usually used as a secondary means of vehicular access to abutting lots and not intended for general traffic circulation.
  • Amusement device: (i) A device or structure open to the public by which persons are conveyed or moved in an unusual manner for diversion, but excluding snow tubing parks and rides, ski terrain parks, ski slopes, and ski trails, and (ii) Passenger tramways…‘open to the public’ means that the public has full access to a device or structure at an event, irrespective of whether a fee is charged.
  • Apartment: A room or group of rooms used as a dwelling unit for one (1) family, with facilities for preparing food therein. See also “dwelling unit.”
  • Appropriateness, certificate of: Required for all proposed exterior alterations, new construction and demolition within a local historic district, with the exception of routine maintenance, repairs and replacements using the same materials, interior alterations and paint colors.
  • Areaway: A sunken area affording access, air or light to a basement door.
  • Arlington County Code


  • Breezeway: An enclosed or unenclosed roofed passageway connecting two (2) buildings or parts of a building.
  • Buildable area: The area of a lot within which a structure can be placed and remaining after the minimum yard and open space requirements of the Zoning Ordinance have been met.
  • Building: An enclosed structure anchored to its foundations and having exterior or party walls and a roof, designed for the shelter of persons, animals or property. When divided by walls without openings, each portion or section of such building shall be regarded as a separate building.
  • Building Code
  • Building line: A line which delineates a required minimum yard of a lot.
  • Building, main: A building in which is conducted the principal use of the lot on which it is situated.
  • Build-to line: A line established along a street frontage extending the full width of a lot, either on or set back from the right-of-way line that defines the block face and establishes building placement.
  • By-right: Describes a usage that may be approved administratively in the respective zoning district subject to all other applicable requirements of the Zoning Ordinance, including the specific use standards in Article 12 of the Zoning Ordinance and site development standards of Article 13 and Article 14 .


  • Certificate of appropriateness: Required for all proposed exterior alterations, new construction and demolition within a local historic district, with the exception of routine maintenance, repairs and replacements using the same materials, interior alterations and paint colors.
  • Chesapeake Bay Preservation Ordinance
  • Chief Building Official: The County official who has the sole responsibility of interpreting and enforcing the Building Code. When there is a need for clarity on provisions of the Code, the Chief Building Official will publish an interpretation for the specific issue. Decisions and interpretations of the Chief Building Official may be appealed to the Local Board of Building Code Appeals.
  • Child care center: Any facility, but not including family day care homes, operated for the purpose of providing non-medical care, protection and guidance to two (2) or more children separated from their parents or guardians for less than a 24-hour period.
  • Condition of Private Property Ordinance
  • Cross connection: A connection between a potable water supply and a non-potable source. At a cross connection, it is possible for contaminants to enter drinking water.
  • Curb grade: The elevation of the established curb in front of the building measured at the center of such front. Where no curb grade has been established, the highway engineer shall establish such curb grade or its equivalent for the purpose of the Zoning Ordinance.


  • Duplex: Two attached dwelling units in a single structure on a single lot with one (1) dwelling unit situated either wholly or partially over or under the other dwelling unit. The building has all exterior characteristics of a one-family attached dwelling, having a single front entrance or one (1) front and one (1) side entrance on the first floor; provided an outside, enclosed stairway located parallel and abutting the rear of the dwelling shall be permitted for direct access to the second floor level.
  • Dwelling or dwelling unit: A building or portion thereof designed exclusively for residential occupancy by one (1) family, which includes provisions for living, sleeping, eating, cooking and sanitation, including one-family detached; semidetached; duplex; townhouse; multiple-family building.


  • Enclosed: Any roofed-over structure or attachment to a structure is enclosed if sides (other than the side or sides where a structure is attached to a main building) are more than 40 percent covered by any material other than customary wire or mesh screening.
  • Energy Conservation Code – Virginia
  • Erosion and Sediment Control Ordinance
  • Exterior features: Exterior features include the architectural style, general design and general arrangement of the entire exterior envelope of a building, structure, site or object, including the kind and texture of the building material and the type and style of all windows, doors, light fixtures, signs, and other appurtenant fixtures, and other natural features. In the case of signs, “exterior features” shall be construed to mean the style, material, size and location of all such signs.


  • Family/caregiver suite: Not more than two (2) rooms, plus a bathroom and “efficiency” kitchen, in a dwelling that are designed, arranged, used or intended for occupancy by either not more than two (2) persons who are related by blood or marriage to the principal occupant of the dwelling or no more than two (2) persons who may be unrelated to the principal occupant of the dwelling, at least one (1) of whom provides care for one (1) or more children of the principal occupant of the dwelling or care for or assistance to one (1) or more elder(s) or person(s) with disabilities who are occupant(s) of the main dwelling.
  • Fence
  • Final survey: This survey must show all existing elements and site improvements, as well as the property in its completed condition, including all setbacks. Any missing elements or additions not consistent with the approved permit may result in a delay of the final inspection or Certificate of Occupancy.  
  • Floodplain Ordinance
  • Form Based Code (FBC): An alternative zoning district for regulating development that helps realize a community’s vision for a specific area. Used in Arlington on Columbia Pike.
  • Frontage: All the property fronting on one side of a street between the two (2) nearest intersecting streets, or other natural barriers.


  • Grade, existing: The ground level or elevation at the outside of a building or elsewhere on a lot prior to any grading or construction, as submitted to the Zoning Division on a grading plan certified by a licensed surveyor, or where a grading plan is not required, as shown on the accepted elevation drawings.
  • Grade, finished: The ground level or elevation at the outside of a building or elsewhere on a lot after grading or construction, as shown on a grading plan certified by a licensed surveyor, or where a grading plan is not required, as submitted to the Zoning Division on the accepted elevation drawings. In the case of a sign, finished grade shall be the elevation of the ground at the site of the sign or at the main entrance to the main building on the site, whichever is lower.
  • Gross parking area: The sum of the ground surface area actually used for parking spaces and the area of the horizontal surface of the floor(s) of a building, measured from the exterior faces of exterior walls, devoted to off-street parking, loading and maneuvering space, including all corridors, air shafts, elevators, stairwells and toilets incidental thereto, but not including area devoted to permitted and accessory uses other than parking and loading.


  • Historic district: A landmark, building, structure, property, land or area that is included within an overlay district as established by ordinance adopted by the County Board in accordance with §11.3 of the Zoning Ordinance . Such overlay district shall not have boundaries that extend farther than the property line of the land pertaining to such district.
  • Home occupationAn accessory use conducted pursuant to §12.9.11. of the Zoning Ordinance, in or from a residential dwelling or its accessory building by a person(s) whose principal residence is on the premises.
  • Homestay, accessory: A home occupation in which an owner(s) or tenant(s) of a dwelling unit who uses such dwelling unit as his/her primary residence, rents to a lodger, either such dwelling unit, or any portion thereof.
  • Hotel or motel: A building designed for transient occupancy containing 10 or more guest rooms or suites, providing living, sleeping and toilet facilities. Individual cooking facilities, a general kitchen or a common dining room may be provided.


  • Incidental sign: A small, noncommercial sign. Examples include but are not limited to signs that provide information or directions that are necessary for the physical use of a property, such as warnings, parking rules or way-finding information. See §13.5.4, §13.6.6, §13.7.7, §13.8.10 and §13.10.8 of the Zoning Ordinance .
  • Inoperative vehicle: Any motor vehicle, recreational vehicle, trailer or semi-trailer which is not in operating condition, or which for a period of 90 days or longer has been partially or totally disassembled by the removal of tires and wheels, the engine or other essential parts required for operation of the vehicle. An inoperative vehicle shall also be considered a vehicle with an observable condition which indicates a state such that it is economically impractical to make such vehicle operative within a reasonable period of time, or which constitutes a health, fire or safety hazard.


  • Junk: Worn-out and discarded material in general that may be turned into some use; odds and ends; old iron or other metal, glass, paper, cordage, old bathroom fixtures, old rubber and old rubber articles, or other waste or discarded material which may be treated or prepared so as to be useful again in some form; rubbish of any kind, including but not limited to old rope, chairs, iron, copper, parts of machinery, bottles, paper, rags; and parts of used automobiles having only a salvage value.


  • Kennel: Any lot or premises on which four (4) or more dogs, more than four (4) months of age, are kept.
  • Kiosk: A free-standing structure which is: one-story, and that is neither more than 10 ft. to the eaves in height nor greater than 150 sq. ft. in area; and constructed predominantly of materials such as glass, wood, plastic, metal or fabric.


  • Lot: A designated parcel, tract or area of land having its principal frontage upon a street or a place permitted under the Subdivisions Ordinance and established by plat or subdivision.
  • Lot, corner: A lot, or portion thereof, not greater than 100 feet in width and situated at the intersection of two (2) or more streets, having an angle of intersection of not more than 135 degrees.
  • Lot coverage: The ratio of an occupied area (buildings and driveways) compared to the total area of a lot.
  • Lot, interior: A lot other than a corner lot.
  • Lot, pipe-stem: A residential lot that has a “pipe” portion, which complies with the minimum requirements for frontage, lot area, lot width, lot depth and building placement in the Zoning and Subdivisions ordinances, and that has a narrower “stem” portion, which does not meet the lot width requirement but provides the required frontage and access to a generally larger and more buildable “pipe” portion of the lot.
  • Lot, through: An interior lot having frontage on two (2) parallel or approximately parallel streets.
  • Lot depth: The distance between the front and rear lot lines. Lot depth is measured along a straight line connecting the midpoint of the front lot line and the midpoint of the rear lot line.
  • Lot frontage: Where a front lot line runs along a straight line along the street right-of-way line, lot frontage shall be the front lot line. Where the front lot line includes an angle or curve along the street right-of-way line, the lot frontage shall be a straight line connecting the points where the two (2) side lot lines meet the street right-of-way line.
  • Lot line: A line of record bounding a lot which divides one (1) lot from another lot or from a public or private street or any other public or private space.
  • Lot line, front: The lot line, or combination of line segments, fronting a street or the legally required access to the lot. On a corner lot, it is the shortest of those lot lines that front a street. Where a corner lot has equal frontage on two (2) or more streets, the front lot line is the lot line on that street on which the greatest number of lots front within the block.
  • Lot line, rear: The lot line most distant from, and most nearly parallel to, the front lot line lot frontage. In addition, the rear lot line shall comply with the following requirements: i) If the lot line that is most distant from the front lot line is a different line from the lot line that is most nearly parallel to the front lot line, then the rear lot line shall be the line whose use results in a greater lot depth. Where two (2) lot lines are equidistant from and equally parallel to the lot frontage, then the point where those two (2) lines intersect shall be used in place of the rear lot line midpoint to measure lot depth. ii) Where two (2) lines are equally distant from and equally parallel to the lot frontage, both lines shall be used to establish the rear yard.
  • Lot line, side: Any lot line other than a front or rear lot line. Where two (2) or more side lot lines are adjoining, they shall be treated as segments of an entire side lot line.
  • Lot width, minimum: The distance determined by dividing the lot area by the lot depth. See the Zoning Ordinance §3.1.8 .
  • Low or moderate income: Income at or below 60 percent of median household income for rental housing units, and at or below 80 percent of median household income for the home ownership program. As used herein, median household income shall be defined as determined from time to time for the Washington Metropolitan Statistical Area by the U.S. Department of Housing and Urban Development. 


  • Main building footprint: The main building footprint shall include all parts of a main building that rest, directly or indirectly, on the ground, including, by way of illustration and not by limitation, attached garages, bay and oriel windows with floor space, chimneys, porches, decks with floor heights that are four (4) feet or higher above finished grade, balconies with horizontal projections that are four (4) feet or more, and covered breezeways connected to a main building.
  • Main building footprint coverage: The percentage determined by dividing that area covered by a main building footprint in square feet by the gross area in square feet of the lot on which the main building is located.
  • Mixed use building: A building constructed to accommodate more than one (1) use category, as identified in the Zoning Ordinance §12.2 , such as, but not limited to, ground floor retail and upper-story residential or office uses, or lower-story hotel and upper-story residential uses.
  • Multiple-family dwelling: A building or portion thereof, designed for occupancy by three (3) or more families living independently of each other.



  • One-family detached dwelling: A residential building containing one (1) dwelling unit designed for one (1) family and located on a single lot with required yards on all four (4) sides.
  • Outlot: A unit of land not usable as a building site and not meeting the requirements of the Zoning Ordinance.
  • Overlay district: Overlay districts are “overlaid” upon other districts and the land so encumbered may be used in a manner permitted in the underlying district only if and to the extent such use also complies within the regulations contained therein.


  • Parking Disclosure
  • Permit authorization affidavit
  • Permit Library
  • Permits
  • Plat: (Informal: survey) A map, drawn to scale, showing the divisions of a piece of land. Many permit applications require a plat of the property in question. Often, a settlement office will provide a copy of the plat to the purchaser of a piece of property at the time of settlement. If you do not have a plat of your property, you may be able to obtain a copy from the Zoning Division if a recent building project on the property required a plat. If Zoning does not have a copy of your plat, you can try contacting your settlement agent, your attorney, your lender, your homeowners association, or, if known, the surveyor who prepared the original plat or the builder who worked on your property. In most cases, the Land Records Division does not have plats of individual properties because there is no legal requirement to record a plat with a deed. You can also obtain a plat from a contractor or by hiring a surveyor.
  • Plat, subdivision: A plat showing an entire neighborhood, on which individual lots appear thumbnail-sized. The plat does not show any physical improvements (e.g., houses or other structures) or landscaping/vegetation. The Land Records Division has subdivision plats and state highway plats.
  • Porch: An unenclosed platform with columns or piers supporting a roof.



  • Resource Protection Area (RPA): The area of land next to a stream, generally 100 feet wide, but may be wider in an area with steep slopes.
  • Responsible party: The owner or tenant, or an individual or business entity designated by the owner or tenant, of a dwelling unit in which an accessory homestay is permitted, who is available 24 hours a day, seven (7) days a week, to respond to and resolve issues and complaints that arise during all times in which the dwelling unit is being used for an accessory homestay, so that a reasonably prompt, in-person response can be made at the accessory homestay when necessary.
  • Retail: (Of companies or individuals) Involved in the sale, lease or rental of new or used products, or providing personal or repair services to the general public.
  • Retaining wall
  • Rezoning: Changing the land classification of a parcel of land.


  • Semidetached dwelling: A residential building with two (2) attached dwelling units located on two (2) lots that share a common wall along the lot line and where each dwelling unit has its own external entrance.
  • Setback: The distance by which a building is required to be “set back” from a lot line or from the nearest building or structure. See the Zoning Ordinance §3.1.9 and §3.2.6.A.
  • Setback line: Either: (a) A line parallel to the street line at a distance therefrom, equal to the required depth of the front yard; or (b) The setback required from any lot line which defines the buildable area of the lot. See “building line.”
  • Site/grading plan: A drawing of a construction site showing existing and proposed topography, environmental controls, demolition and improvements to the land.
  • Snow Removal Ordinance
  • Standing space: An off-street parking space for the temporary waiting in line of one (1) automobile for service or delivery of goods to the automobile or its occupants at another place on the premises. See the Zoning Ordinance §14.3.3.C.2 .
  • Step-back: An area of a façade above the first floor of a building or structure that is located a set distance further back from the façade or story below it.
  • Stoop: A raised platform that serves as an entrance to a building, may be roofed, has no supporting posts and is not enclosed.
  • Stormwater Management Ordinance
  • Story: That portion of a building included between the surface of any floor and the surface of the next floor above it; or, if there be no floor above it, then the space between such floor and the ceiling next above it.
  • Story, half: A story under a gable, hip or gambrel roof, the wall plates of which, on at least two (2) opposite exterior walls, are not more than two (2) feet above the floor of such story, and if the roof has a dormer, the dormer wall is set back at least six (6) inches from the front of the wall or main wall below and the width of the dormer is less than 50 percent of the width of the roof.
  • Structure: Anything constructed or erected that requires location on the ground or attached to something having a location on the ground.
  • Structural alteration: Any change that would tend to prolong the life of the supporting members of a building or a structure, such as bearing walls, columns, beams or girders.


  • Townhouse: One of a series of three (3) or more attached similar dwelling units, located on separately-owned lots or on a single lot, separated by common party walls without openings extending from basement to roof, and where each unit has its own external entrance.
  • Transitional site: A lot or part thereof located in an R, S-3A or RA district and lying within a distance of 200 feet from the boundary of any C or M district when such lot or part thereof: (a) Is abutting such boundary but not across any part of a street therefrom; and (b) Does not abut at more than one (1) lot line, a side lot line in an R, S-3A or RA district. See the Zoning Ordinance §12.8 .
  • Trellis: A vertical frame supported only by posts placed in a single plane, supporting open latticework and used as a screen or a support for growing vines or plants.


  • Urban regional shopping center: A building(s) or the portion of a building that includes a minimum of 500,000 square feet of retail, entertainment and food establishment uses configured in at least two (2) stories and that is not bisected by any street. An urban regional shopping center is connected by at least one (1) interior or exterior shared pathway fronted by retail, entertainment and food establishment uses.
  • Urban regional shopping center façade: An exterior vertical plane, face or side of an urban regional shopping center building that contains a minimum of 50 percent retail, entertainment and food establishment uses on each story. Neither articulations nor off-sets in the wall of less than five (5) feet shall be considered separate façades. An urban regional shopping center façade is either: (1) Façade type A: an urban regional shopping center façade(s) with a minimum of 50 percent fenestration on the ground story and a minimum of 25 percent fenestration on the remainder of the urban regional shopping center façade; or (2) Façade type B: an urban regional shopping center façade(s) that does not qualify as façade type A.
  • Use or use type: The purpose or activity for which land, or any structure thereon, is arranged, designed or intended, or for which it is occupied or maintained.
  • Use, principal: The use conducted as a primary activity upon the lot on which it is located.
  • Use, short term: A use established for a fixed period of time with the intent to discontinue the use upon the expiration of the time.
  • Use, transitional: A use permitted only on a transitional site under the regulations for the district and not permitted elsewhere in the district except on transitional sites, and subject to all other regulations for the district.


  • Vehicle storage lot: Any land or building where two (2) or more wrecked, abandoned, impounded or new vehicles of any kind are stored prior to repair, disposal, claim or sale, but does not include the repair, wrecking, dismantling or salvaging of said vehicles or their parts.
  • Virginia Uniform Statewide Building Code


  • Wall check: Confirms that the location of foundation walls in relation to property lines is consistent with the issued building permit, plat, and plans. 
  • Wall, retaining
  • Wall sign: Any sign that is affixed directly to or suspended from a wall, marquee, mansard wall or parapet wall of a building, with the exposed face of the sign in a plane approximately parallel to and projecting no more than 18 inches from the face of the wall. A wall sign may be either of one-piece construction or of individual connected or related letters or symbols. See §13.6.9, §13.7.13, §13.8.15, §13.9.5 and §13.10.11.
  • Window sign: Any permanent or temporary sign, including any decal, that is legible from the outside, including plazas, public streets and parking lots, and that is placed on the outside or inside face of a window or mounted within two (2) feet of the inside face of the window. See §13.6.10, §13.8.16 and §13.10.12 .



  • Yard: An open space, other than a court, on a lot, which space: (a) Either, (1) lies between a lot line and a building, a building group or a use not involving a building, or (2) on a vacant lot abuts a lot line and has a uniform depth or width, as the case may be, equal to the minimum depth or width of yard required under the regulations for the district in which is situated the lot on which such yard is located; and (b) Is unoccupied and unobstructed from the ground upward except for certain features specified in the Zoning Ordinance §3.2.5 .
  • Yard, front: A yard extending across the full width of the lot and abutting the front lot line.
  • Yard, rear: A yard extending the full width of the lot and abutting the rear lot line.
  • Yard, side: A yard abutting a side lot line and extending from the front yard to the rear yard, or in the absence of either of such yards, to the front or rear lot line.
  • Yard, required: The open space required between a lot line and the buildable area of a lot, within which no structure shall be located except as provided in the Zoning Ordinance. See also “setback.”


  • Zoning Administrator: The person appointed by the County Manager to enforce and carry out duties as set out in the Zoning Ordinance. The Zoning Administrator may appoint deputies and assistants as are authorized from time to time by the County Manager. The Staff Directory lists the current Zoning Administrator.
  • Zoning Compliance Letter: A letter that verifies zoning entitlements and encumbrances for a specific property.
  • Zoning Determinations: Formal decisions by the Zoning Administrator specifically interpreting zoning and/or land use regulations.
  • Zoning Ordinance