We're still verifying Fairfax County, VA's answers against the county code.

R-20Residential (R-20), 20 DU/acre

Fairfax County, VA · Fairfax County Zoning Ordinance

R-20 permits higher-density multifamily residential. Max 20 DU/acre. Attached: height 35ft, front 5ft, side 10ft, rear 20ft. MF/other: up to 65ft. Common near commercial corridors and transit.

Development standards in R-20

Front setback	Single-family attached and stacked townhouses: At least 5 ft “[1] Refer to subsection 5108.5 for additional provisions that may qualify the setback requirements. Refer to subsection 5100.2.D(1)(d) for provisions that qualify the setback requirements for individual units in single-family attached dwellings and stacked townhouses. Setback requirements may be waived by the Board in accordance with 5100.2.D(1)(e).”	2102
	Multifamily: At least 20 ft for a building up to 45 ft tall, 21 ft up to 50 ft, 24 ft up to 55 ft, 26 ft up to 60 ft, 28 ft up to 65 ft, 31 ft up to 70 ft, 33 ft up to 75 ft, 35 ft up to 80 ft, 38 ft up to 85 ft, 40 ft up to 90 ft; no figure above that height “[1] Refer to subsection 5108.5 for additional provisions that may qualify the setback requirements. Refer to subsection 5100.2.D(1)(d) for provisions that qualify the setback requirements for individual units in single-family attached dwellings and stacked townhouses. Setback requirements may be waived by the Board in accordance with 5100.2.D(1)(e).”	2102
	Other principal uses: At least 20 ft for a building up to 45 ft tall, 21 ft up to 50 ft, 24 ft up to 55 ft, 26 ft up to 60 ft, 28 ft up to 65 ft, 31 ft up to 70 ft, 33 ft up to 75 ft, 35 ft up to 80 ft, 38 ft up to 85 ft, 40 ft up to 90 ft; no figure above that height “[1] Refer to subsection 5108.5 for additional provisions that may qualify the setback requirements. Refer to subsection 5100.2.D(1)(d) for provisions that qualify the setback requirements for individual units in single-family attached dwellings and stacked townhouses. Setback requirements may be waived by the Board in accordance with 5100.2.D(1)(e).”	2102
Side setback	Single-family attached and stacked townhouses: At least 10 ft “[1] Refer to subsection 5108.5 for additional provisions that may qualify the setback requirements. Refer to subsection 5100.2.D(1)(d) for provisions that qualify the setback requirements for individual units in single-family attached dwellings and stacked townhouses. Setback requirements may be waived by the Board in accordance with 5100.2.D(1)(e).”	2102
	Multifamily: At least 10 ft for a building up to 25 ft tall, 12 ft up to 30 ft, 14 ft up to 35 ft, 17 ft up to 40 ft, 19 ft up to 45 ft, 21 ft up to 50 ft, 24 ft up to 55 ft, 26 ft up to 60 ft, 28 ft up to 65 ft, 31 ft up to 70 ft, 33 ft up to 75 ft, 35 ft up to 80 ft, 38 ft up to 85 ft, 40 ft up to 90 ft; no figure above that height “[1] Refer to subsection 5108.5 for additional provisions that may qualify the setback requirements. Refer to subsection 5100.2.D(1)(d) for provisions that qualify the setback requirements for individual units in single-family attached dwellings and stacked townhouses. Setback requirements may be waived by the Board in accordance with 5100.2.D(1)(e).”	2102
	Other principal uses: At least 10 ft for a building up to 25 ft tall, 12 ft up to 30 ft, 14 ft up to 35 ft, 17 ft up to 40 ft, 19 ft up to 45 ft, 21 ft up to 50 ft, 24 ft up to 55 ft, 26 ft up to 60 ft, 28 ft up to 65 ft, 31 ft up to 70 ft, 33 ft up to 75 ft, 35 ft up to 80 ft, 38 ft up to 85 ft, 40 ft up to 90 ft; no figure above that height “[1] Refer to subsection 5108.5 for additional provisions that may qualify the setback requirements. Refer to subsection 5100.2.D(1)(d) for provisions that qualify the setback requirements for individual units in single-family attached dwellings and stacked townhouses. Setback requirements may be waived by the Board in accordance with 5100.2.D(1)(e).”	2102
Rear setback	Single-family attached and stacked townhouses: At least 20 ft “[1] Refer to subsection 5108.5 for additional provisions that may qualify the setback requirements. Refer to subsection 5100.2.D(1)(d) for provisions that qualify the setback requirements for individual units in single-family attached dwellings and stacked townhouses. Setback requirements may be waived by the Board in accordance with 5100.2.D(1)(e).”	2102
	Multifamily: At least 25 ft for a building up to 55 ft tall, 26 ft up to 60 ft, 28 ft up to 65 ft, 31 ft up to 70 ft, 33 ft up to 75 ft, 35 ft up to 80 ft, 38 ft up to 85 ft, 40 ft up to 90 ft; no figure above that height “[1] Refer to subsection 5108.5 for additional provisions that may qualify the setback requirements. Refer to subsection 5100.2.D(1)(d) for provisions that qualify the setback requirements for individual units in single-family attached dwellings and stacked townhouses. Setback requirements may be waived by the Board in accordance with 5100.2.D(1)(e).”	2102
	Other principal uses: At least 25 ft for a building up to 55 ft tall, 26 ft up to 60 ft, 28 ft up to 65 ft, 31 ft up to 70 ft, 33 ft up to 75 ft, 35 ft up to 80 ft, 38 ft up to 85 ft, 40 ft up to 90 ft; no figure above that height “[1] Refer to subsection 5108.5 for additional provisions that may qualify the setback requirements. Refer to subsection 5100.2.D(1)(d) for provisions that qualify the setback requirements for individual units in single-family attached dwellings and stacked townhouses. Setback requirements may be waived by the Board in accordance with 5100.2.D(1)(e).”	2102
Maximum height	Single-family attached: At most 35 ft	2102
	Stacked townhouses: At most 60 ft	2102
	Multifamily: At most 90 ft	2102
	Other principal uses: At most 90 ft	2102
Maximum FAR	Other principal uses, all uses other than residential: At most 0.7	2102
Maximum FAR	Single-family attached and stacked townhouses and multifamily: No requirement	2102
Max density	Single-family attached and stacked townhouses: At most 20 dwellings per acre	2102
Max density	Multifamily: At most 20 dwellings per acre	2102
Minimum lot size	Other principal uses: At least 10,000 sq ft	2102
Minimum lot size	Single-family attached and stacked townhouses and multifamily: No requirement	2102
Minimum lot width	Single-family attached and stacked townhouses: At least 18 ft “[2] District size and lot width may be modified in accordance with subsection 5100.2.K.”	2102
	Other principal uses, interior lot: At least 75 ft “[2] District size and lot width may be modified in accordance with subsection 5100.2.K.”	2102
	Other principal uses, corner lot: At least 100 ft “[2] District size and lot width may be modified in accordance with subsection 5100.2.K.”	2102
	Multifamily: No requirement	2102
Minimum open space	At least 30%	2102

Each row above is the ordinance’s own rule, written out in words and cited to its section. Where a figure depends on what you build (the kind of building, a conventional or cluster subdivision, an interior or corner lot, or the building’s height), each case is its own line; where it depends on the building height, the cited table says how that height is measured. An affordable dwelling unit development has its own table with different figures; see 2102.

Read from Fairfax County Zoning Ordinance, effective through 2026-07-01. We last checked with the publisher on 2026-09-14 and found nothing newer -- a check on that date, not a promise about today.

How complete is this market? Across 239,083 parcels we answer 96.1% of the 6 questions this site is built to answer, each with a source you can check. The rest are shown as “not recorded” rather than filled in — we would rather be short than wrong. A further 13,550 properties inside the county line are zoned by an incorporated town with its own ordinance, not by the county, so this county ordinance does not govern them and they are not counted above or below — which is why we publish this market as Fairfax County (excl. Vienna and Herndon). Look one of those up and we will tell you which town governs it.

Permitted uses in R-20

AllowedMultifamily Residential
Table 4101.1 lists “Dwelling, Multifamily” as P in the R-20 column. P = permitted by right; SE = special exception; SP = special permit; A = accessory only; AP = administrative permit (Table 4101.1).
AllowedTownhouses
Table 4101.1 lists “Dwelling, Single-Family Attached” as P in the R-20 column. P = permitted by right; SE = special exception; SP = special permit; A = accessory only; AP = administrative permit (Table 4101.1).
DependsHome Occupation Varies
Depends: administrative permit, only if the use is a type or location that Sec. 4102.7.H allows here and the use stays within the limits in Sec. 4102.7.H; special permit, only if the use is a type or location that Sec. 4102.7.H allows here and the use stays within the limits in Sec. 4102.7.H; this table cell allows the use in more than one way (administrative permit or special permit), and the use standards in Sec. 4102.7.H set which way applies
Table 4101.1 lists “Home-Based Business” as AP/SP in the R-20 column. P = permitted by right; SE = special exception; SP = special permit; A = accessory only; AP = administrative permit (Table 4101.1).
DependsSTR - Short-Term Rentals Varies
Depends: administrative permit, only if the use is a type or location that Sec. 4102.7.O allows here and the use stays within the limits in Sec. 4102.7.O
Table 4101.1 lists “Short-Term Lodging” as AP in the R-20 column. P = permitted by right; SE = special exception; SP = special permit; A = accessory only; AP = administrative permit (Table 4101.1). Fairfax defines this as a room or space intended for TRANSIENT OCCUPANCY for a charge, and expressly NOT a bed and breakfast, hotel, motel or accessory living unit (Article 9). It needs a short-term lodging permit from the Zoning Administrator, and the operator must be a permanent resident of the property (Sec. 4102.7.O).
Not AllowedCommercial / Retail
Table 4101.1 has no entry for “Retail Sales, General” in the R-20 column. The table's own legend: a blank cell indicates the use cannot be established in that zoning district (Table 4101.1).

"Conditional" means the use generally requires a public hearing or special-exception approval — a very different timeline and risk profile from a by-right permit.

This is the zone. What about the parcel?

Zone rules are the starting point — the answer for a specific property also depends on lot size, overlays, existing improvements and site conditions. Run a free address lookup to see what applies to one property.

Look up an address

Sources

Fairfax County Zoning Ordinance — read the ordinance
Fairfax County — official zoning map / authority
Standards as recorded by Zonescore: Fairfax County Zoning Ordinance (enCodePlus, current)

Values are read from the Fairfax County Zoning Ordinance.

Other Fairfax County zones

C-1 C-2 C-3 C-4 C-5 C-6 C-7 C-8 I-2 I-3 I-4 I-5 I-6 I-I PCC PDC PDH PDH-1 PDH-12 PDH-16 PDH-2 PDH-20 PDH-3 PDH-30 PDH-4 PDH-40 PDH-5 PDH-8 PRC PRM PTC R-1 R-12 R-16 R-2 R-3 R-30 R-4 R-5 R-8 R-A R-C R-E R-MHP