Nonconforming Buildings and Structures

Nonconformity is a concept which pervades the zoning ordinance and its application. A nonconformity is anything that was legally built, established, and/or created but is no longer in compliance with the current zoning regulations. This can happen for several reasons but most often a nonconformity arises due to a change to the zoning ordinance – including the adoption of zoning regulations. Although a nonconformity is not compliant with the zoning regulations, it is permitted to continue provided:

  • The nonconformity does not cease or discontinue for more than two years.
  • The nonconformity is not expanded or enlarged.

If either of these two things occur, the nonconforming status is extinguished and the nonconformity needs to be brought into compliance with the current zoning regulations.


What does it mean when a one- or two-family dwelling is nonconforming?

Because there are multiple zoning regulations governing one- and two-family lots and dwellings, it is not uncommon to have multiple nonconformities on a single property. Some of the items the zoning ordinance regulates include lot size and width, building height, lot coverage, street and lot line setbacks, and building footprint size. A given property, and the structures located on it, could be nonconforming to any or all of these regulations. Some of the most common nonconformities are elaborated below.

Reference document: Report on Status of Nonconforming One- and Two-Family Dwelling (December 22, 2015).

What does it mean when a lot is nonconforming?

The Zoning Ordinance sets minimum dimensional standards for lot size in every zoning district. For one- and two-family dwelling districts these standards include minimum lot area and minimum average lot width. In addition, every lot must have frontage along a street that is at least 30 feet wide. If a lot does not meet all standards, it is not compliant with the zoning ordinance, and as a result cannot be built on (also known as ‘buildability’ or being ‘buildable’).

However, if a lot that does not meet the minimum dimensional standards was platted and recorded in the Arlington County land records prior to July 15, 1950, it is considered a nonconforming lot, and as such can be built on in the same manner as a lot which meets all the minimum standards.

Lot width: Minimum lot width is regulated in each zoning district and is articulated in the density and dimensional standards for the subject zoning district. Minimum lot width is measured at the midpoint of the portion of the lot being used for the calculation. When a lot does not meet the minimum required lot width for the subject zoning district, it is nonconforming with respect to lot width (§3.1.8).

Lot area: Minimum lot area is regulated in each zoning district and is articulated in the density and dimensional standards for the subject zoning district. Minimum lot area is measured as the total number of square feet contained in the lot. When a lot does not meet the minimum required lot area for the subject zoning district it is nonconforming with respect to lot area (§3.1.8).

Frontage: By definition, a lot must have frontage on a street (§3.1.1.A.1). If a lot does not have frontage on a street, or in another place as legally established by plat or subdivision, it may be a nonconforming lot.

What does it mean when a building or structure is nonconforming?

The zoning ordinance regulates the general placement, height, and density/massing of buildings and structures. For all buildings and structures, these regulations include minimum setbacks from streets and lot lines, maximum building height, maximum building footprint, and maximum percentage of a lot which can be covered with buildings and structures.

When a building or structure does not meet all these regulations, it is considered noncompliant. The only means to construct a noncompliant building or structure is by obtaining a variance and/or a use permit from the Board of Zoning Appeals (BZA).

However, when a building or structure does not meet one or more of these standards but was built before a specific zoning regulation was in effect, then the building is considered nonconforming. While nonconforming buildings and structures are allowed to continue without BZA approval, any alternation which enlarges or expands the nonconformity is typically prohibited.

Placement: When a dwelling does not comply with front, side, or rear setback requirements of the Zoning Ordinance, the building is nonconforming with respect to placement. Setbacks provide a minimum required distance from a lot line or nearest building or structure, and all setbacks must be met in order for the dwelling to be conforming to requirements (§3.1.9 and §3.2.6).  Note that for two-family dwellings, setbacks are regulated based on the height of the dwelling, therefore a two-family dwelling may be nonconforming if the relationship between height and setbacks does not meet the required ratio (§3.2.6.A.2(e)).

Coverage: There are multiple components of coverage regulated by the Zoning Ordinance, and a property must comply with each component independently of all other components.  A property is nonconforming with respect to coverage if it is out of compliance with any of the included components (§3.2.5).  Each is described below.

  • Lot coverage (defined in §3.1.4.A): The Zoning Ordinance describes all the items that are counted as part of lot coverage. The combined area of all of these items relative to the area of the lot, is used to calculate the lot coverage. When the lot coverage exceeds the percentage allowed by the Zoning Ordinance for the subject zoning district, the building is nonconforming.
  • Main building footprint (defined in §3.1.4.C): Each one- and two-family zoning district has a maximum footprint (in square feet) allowed for the main building on the lot, regardless of the size of the lot. The main building on the lot is typically the dwelling, and the main building footprint is calculated in square feet, to include any part of the dwelling that rests directly or indirectly on the ground. A building is nonconforming with respect to coverage if exceeds the maximum main building footprint size for the subject zoning district.
  • Main building footprint coverage: Additionally, the Zoning Ordinance regulates the maximum percentage of the lot that can be covered by the main building, referred to as the main building footprint coverage. This percentage is the ratio of the main building footprint to the total area of the lot. A building is nonconforming with respect to coverage if it exceeds the main building footprint coverage for the subject zoning district.

Height: In R-districts, building height (§3.1.6.A.1) is measured as an average of the heights at four defined points on the perimeter of the building. Height (§3.1.6.A) for each of those points is measured as the vertical distance from existing grade to the highest point of a flat roof; the deck of a mansard roof; or the midpoint between the eaves and the highest ridge point for a gable, hip or gambrel roof.

  • When the height of a one- or two-family dwelling exceeds the maximum height allowed in the subject zoning district, the building is nonconforming with respect to height.
  • Additional height requirements apply to two-family dwellings, in that maximum height is related to the width of the setbacks (§3.2.6.A.2(e)). A two-family dwelling may be nonconforming if the relationship between height and setbacks does not meet the required ratio.

Accessory Buildings and Structures
Accessory buildings and structures are buildings and structures that are incidental to the permitted principal use on the lot. On one- and two-family lots, examples of accessory buildings and structures may include detached garages, sheds, swing sets, swimming pools, trellises, barbeques/outdoor fireplaces and other similar structures related to the dwelling.  All of the requirements described above also apply to accessory buildings and structures.  Some accessory buildings and structures are required to follow the same rules as the dwelling, while others have specific requirements. Accessory buildings and structures may be nonconforming if the building or structure:

  • Does not meet required setbacks from property lines or from the main dwelling (§3.2.6.A.2.(c))
  • Exceeds height measurements (which in many cases are lower than that allowed for the dwelling)
  • Exceeds the number of allowed stories in certain locations on the lot
  • Exceeds the maximum size allowed for the structure
  • Exceeds the maximum lot coverage requirements for the subject zoning district (accessory buildings are a component of lot coverage and are added to the coverage of the main building on the lot when calculating lot coverage)

What is a nonconforming use?

The zoning ordinance regulates the uses that are allowed on a particular property. Every zoning district identifies whether a use is permitted by-right, permitted by a special exception, or prohibited entirely. A use is generally considered to be nonconforming if the use was allowed by the zoning ordinance when it was established but is no longer allowed due to amendments to the zoning regulations.

For one- and two-family dwellings, nonconforming uses typically involve multiple units in the same dwelling or detached accessory dwellings. The use is typically attached a building or structure. While a nonconforming use is allowed to continue – even if prohibited under the current zoning regulations – the nonconforming use status is extinguished if the nonconforming building or structure is altered or removed.

Example of nonconforming use in residential dwelling districts:
During the 1930s, the Arlington County Zoning Ordinance allowed duplex dwellings on single-family lots provided the duplex resembled a single-family dwelling from the exterior. In 1942, the zoning ordinance was amended and duplexes were no longer permitted on single-family lots. This rendered all of the duplexes built on single-family lots prior to 1942 nonconforming, and were allowed to continue to be used as duplexes.  However, if one of these nonconforming duplexes was renovated into a single-family dwelling after 1942, it could not be converted back to a duplex because the renovation to a single-family dwelling extinguished the dwelling’s nonconforming status. Likewise, if the nonconforming duplex had been demolished, it could not be rebuilt; only a single-family dwelling could be built.

What renovations are allowed if my house or lot is nonconforming?

The Zoning Ordinance includes several regulations designed to facilitate the renovation of older housing stock in the County. Recognizing that many of the existing one- and two-family dwellings in the County no longer conform to current Zoning regulations, there are several renovations that are allowed, even when the dwelling is nonconforming. Some of these renovations may be approved by the Zoning Administrator, and others require approval by the BZA.

Allowed with Zoning Administrator approval (by-right)
By-right renovations are those that may be approved by the Zoning Administrator (although permits may be required). These by-right allowances facilitate the retention of older housing stock in the County and the ability for homeowners to make basic renovations to their homes to meet their needs.

Some of the commonly requested renovations allowed by-right on a legally nonconforming one- or two-family dwelling or on a one- or two-family dwelling on a legally nonconforming lot.  Because every renovation is different and may impact multiple zoning regulations, please consult with Zoning to find out if your proposed renovation is allowed by-right.

  • Renovation to an existing dwelling, where the renovation is completely contained within the exterior walls of a one- or two-family dwelling located in the R-20, R-10, R-8, R-6, R-5 or R2-7 zoning district. This allowance includes replacement, enlargement or creation of new doors, windows or other openings in existing exterior walls, but does NOT allow replacement of an entire exterior wall (§16.2.3.B)
  • Addition to an existing dwelling that encroaches into a required side, rear, and/or front yard(s), so long as the new construction meets all zoning requirements for the subject property (§16.2.4.E)
  • Addition to an existing dwelling that is built straight up atop an existing nonconforming wall(s). This provision, however, does NOT allow construction of new eaves that encroach further than allowed by the Zoning Ordinance, nor does it allow construction above encroaching garages or porches (§16.2.4.E).
  • Enclosure of an encroaching porch that was built prior to November 20, 1976 (§3.2.6.A.3(c))
  • Use of a lot for any use allowed by-right in the zoning district, on lots in R-20, R-10, R-8, R-6, and R-5 districts that have less width and/or area than required in the subject district, so long as the lot was recorded under one ownership prior to July 15, 1950 (§16.1.1)

Allowed with Board of Zoning Appeals (BZA) approval
The BZA consists of five members who are appointed by the Circuit Court. The duties of the BZA include hearing cases for use permits or variances.

Use permits (§15.6.6.A)
The BZA may approve use permits that allow modification of placement (setback) requirements for buildings or structures in R-20, R-10, R-8, R-6, R-5 and R2-7 zoning districts where there is no option in the Zoning Ordinance for the County Board to modify these requirements (such as by special exception use permit described in §15.4 or site plan described in §15.5).

When the BZA approves a use permit to allow such modification of placement, it may impose conditions on the approval that it deems necessary to serve the public interest, including limiting the duration of the use permit. In approving a use permit, the BZA must make certain findings:

  • The proposal does not adversely affect the health or safety of persons residing in the neighborhood.
  • The proposal is not detrimental to the public welfare or injurious to property or improvements in the neighborhood.
  • The proposal will not be in conflict with the purposes of master plans and land use- and zoning-related policies of the County.

In making these findings, the BZA considers whether the modification will promote compatibility of development with the surrounding neighborhood because the structure’s overall footprint size and placement are similar to the structures on the properties surrounding the subject lot; and whether the modification will help preserve natural land form, historical features and/or significant trees.

Some of the commonly requested renovations requiring approval of a BZA use permit include the following (these requests require BZA approval regardless of whether the dwelling is conforming or nonconforming):

  • Front porch encroaching more than the allowed four feet into a front yard
  • Structures, such as areaways, window wells, air conditions units, decks and stoops that encroach more than the allowed four feet into a required yard
  • Additions to an existing dwelling that encroach into a required yard
  • Structures that encroach into a required yard
  • 1- and 1½-story accessory buildings on corner lots
  • Eaves that encroach into required yards on additions built atop an existing building footprint

Variances (See Virginia Code 15.2-2201).  The BZA may approve variances for reasonable deviation(s) from provisions regulating the size or area of a lot or parcel of land, or the size, area, bulk or location of a building or structure when:

  • The strict application of the ordinance would result in unnecessary or unreasonable hardship to the property owner.
  • Such need for a variance is not shared generally by other properties, provided such variance is not contrary to the intended spirit and purpose of the ordinance, and would result in substantial justice being done.
  • A variance may NOT be approved for a change in use.

Allowed with County Board approval
For certain lots, which exist only in limited quantity in the County, and under limited circumstances, County Board approval is required for renovations.

Pipe-stem lots
Modification of zoning requirements for new construction on pipe-stem lots created prior to March 18, 2003 require approval by the County Board (§10.1.4).