Where can I put a dwelling, multifamily – adu development in Fairfax County, VA?

Fairfax County, VA, excluding the incorporated towns, which run their own zoning.

Dwelling, Multifamily – ADU Development

Allowed by right in 6 districts

District	Properties loaded	Code	What says so
R-12 the use table's own cell	7,817 no ZIP in the county's record (218), 20120 (143), 20151 (25), 20170 (38), 20171 (104), 22003 (1,310), 22015 (180), 22030 (86), 22031 (873), 22032 (257), 22041 (379), 22042 (125), 22043 (284), 22044 (26), 22079 (485), 22101 (22), 22124 (81), 22151 (32), 22152 (128), 22180 (166), 22181 (420), 22182 (618), 22304 (148), 22306 (445), 22307 (74), 22309 (135), 22310 (313), 22312 (702)	P	Sec. 4101 Read from the use table: Table 4101.1, row "Dwelling, Multifamily – ADU Development", column "R-12", reads "P". Sec. 4101.1 says: A “P” in a cell of Table 4101.1 indicates that the use can be established by right in that zoning district, subject to compliance with related use standards.
R-16 the use table's own cell	528 no ZIP in the county's record (8), 20121 (1), 22030 (2), 22041 (121), 22042 (48), 22043 (203), 22124 (18), 22309 (49), 22310 (78)	P	Sec. 4101 Read from the use table: Table 4101.1, row "Dwelling, Multifamily – ADU Development", column "R-16", reads "P". Sec. 4101.1 says: A “P” in a cell of Table 4101.1 indicates that the use can be established by right in that zoning district, subject to compliance with related use standards.
R-20 the use table's own cell	17,328 no ZIP in the county's record (109), 20121 (812), 20151 (581), 20191 (169), 22003 (3,094), 22015 (303), 22030 (10), 22031 (577), 22032 (193), 22033 (262), 22041 (390), 22042 (706), 22043 (752), 22044 (63), 22046 (488), 22060 (1), 22079 (762), 22101 (35), 22102 (1,295), 22124 (778), 22150 (106), 22151 (1), 22152 (51), 22153 (1), 22180 (4), 22181 (277), 22182 (156), 22302 (31), 22303 (63), 22306 (915), 22307 (1,465), 22309 (2,420), 22310 (114), 22311 (106), 22312 (238)	P	Sec. 4101 Read from the use table: Table 4101.1, row "Dwelling, Multifamily – ADU Development", column "R-20", reads "P". Sec. 4101.1 says: A “P” in a cell of Table 4101.1 indicates that the use can be established by right in that zoning district, subject to compliance with related use standards.
R-30 the use table's own cell	6,428 no ZIP in the county's record (6), 20190 (44), 22041 (754), 22043 (252), 22044 (1,617), 22102 (2,497), 22180 (1), 22303 (1,224), 22306 (30), 22310 (2), 22312 (1)	P	Sec. 4101 Read from the use table: Table 4101.1, row "Dwelling, Multifamily – ADU Development", column "R-30", reads "P". Sec. 4101.1 says: A “P” in a cell of Table 4101.1 indicates that the use can be established by right in that zoning district, subject to compliance with related use standards.
R-5 the use table's own cell	11,400 no ZIP in the county's record (483), 20120 (118), 20121 (1,318), 20151 (497), 20170 (5), 22003 (541), 22015 (1,061), 22027 (107), 22031 (324), 22032 (473), 22033 (456), 22042 (69), 22043 (37), 22060 (1), 22079 (557), 22101 (111), 22124 (137), 22150 (246), 22151 (1), 22152 (617), 22153 (1,139), 22180 (59), 22181 (78), 22182 (121), 22303 (97), 22306 (811), 22307 (1), 22310 (237), 22312 (90), 22315 (1,608)	P	Sec. 4101 Read from the use table: Table 4101.1, row "Dwelling, Multifamily – ADU Development", column "R-5", reads "P". Sec. 4101.1 says: A “P” in a cell of Table 4101.1 indicates that the use can be established by right in that zoning district, subject to compliance with related use standards.
R-8 the use table's own cell	21,478 no ZIP in the county's record (600), 20120 (1,731), 20121 (2,235), 20151 (539), 20170 (798), 20191 (165), 22003 (332), 22015 (791), 22030 (220), 22031 (1,009), 22032 (1,164), 22033 (344), 22041 (79), 22042 (51), 22043 (719), 22044 (58), 22079 (1,321), 22101 (586), 22102 (178), 22124 (124), 22150 (471), 22151 (295), 22152 (943), 22153 (640), 22180 (83), 22181 (726), 22182 (299), 22303 (1,167), 22306 (402), 22307 (638), 22309 (695), 22310 (1,440), 22312 (169), 22315 (466)	P	Sec. 4101 Read from the use table: Table 4101.1, row "Dwelling, Multifamily – ADU Development", column "R-8", reads "P". Sec. 4101.1 says: A “P” in a cell of Table 4101.1 indicates that the use can be established by right in that zoning district, subject to compliance with related use standards.

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This answer is good through July 1, 2026 — that is the date the ordinance we hold runs to, as published by Fairfax County. We last checked with the county on September 14, 2026 and found nothing newer. That is a check on that date, not a promise about today.

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What this does not cover

369,385 properties are loaded, in 67 ZIP codes (20120, 20121, 20124, 20151, 20152, 20153, 20164, 20170, 20171, 20172, 20190, 20191, 20192, 20194, 20195, 20196, 22003, 22009, 22015, 22027, 22030, 22031, 22032, 22033, 22035, 22039, 22041, 22042, 22043, 22044, 22046, 22060, 22066, 22079, 22082, 22101, 22102, 22106, 22124, 22150, 22151, 22152, 22153, 22159, 22160, 22161, 22180, 22181, 22182, 22183, 22185, 22203, 22204, 22206, 22207, 22213, 22302, 22303, 22304, 22306, 22307, 22308, 22309, 22310, 22311, 22312, 22315). Properties outside those ZIPs are not counted here at all. A further 14,528 carry no street address in the county’s own parcel record, so they fall in no ZIP above — they are still loaded and still counted in the 369,385.
A further 130,979 properties carry a parcel zone code this page cannot match to a single column of the use table: (none), AC, AC;CS, AC;CS;M;PR;R, AC;RMU, AC;RMU;T, AC;RS, AE, AE;RMU;RS, AE;RS (2 variants, e.g. AE;RS-10), AE;T, AW, AW;RS (2 variants, e.g. AW;RS-10), AW;T and 63 more.
2,474 of those lie in TWO OR MORE districts at once. Their code below holds every district the parcel really shares area with, joined by a semicolon — AC;CS, AC;CS;M;PR;R-1;RMU;RS-10;RS-12.5, AC;RMU, AC;RMU;T, AC;RS-10 and 346 more. The ordinance does not say the larger share wins, so we do not pick one: the parcel is shown as straddling and is not counted under either district.
10,070 of those carry a code that looks like one of the districts above and is not one. CC, CO, CP, CS, R-10, R-15 and 7 more — these are separate zone classifications in their own right, not the same zone with something added, and the use table has no column for them. We do not fold them in.
(none) above means a parcel we could not place inside any zoning district on the county's zoning map — 1,697 of them. We hold no zone on the parcel record we fetch from the county, so this is our reading of its map rather than a blank in its data.
Owner filters. This county publishes no ownership record we can read, so we cannot tell you who owns anything here — not that nobody matches. It does publish sale history and assessed values, and we hold both, so the two filters below work here even though the owner ones cannot. Owned for: under 2 years 26,000+; 2-5 years 41,000+; 5-10 years 71,000+; 10-20 years 79,000+; 20-30 years 70,000+; 30+ years 58,000+. 21,000+ properties have no transfer date we can read and are in no bucket. 39,399 are worth more as land than as building — the county’s own land assessment is at least 50% of its total. 287 properties carry no pair of assessments and are left out of that count rather than treated as zero, which would make every one of them look like bare land.
Sale history and assessed values from Fairfax County Department of Tax Administration records, retrieved October 5, 2026.
14,528 of the properties above are listed as “no ZIP in the county’s record” in the ZIP breakdowns. 14,528 carry no street address at all in the county’s data and 0 carry a street but no city or ZIP — so we cannot place them in a ZIP, and we do not guess one. They are still counted in the district totals.
119 of them (0.0%) carry a ZIP that does not start 220 or 201 or 221 or 223 — the prefixes covering 99% of the addresses this county publishes. These are the county’s own values, shown as published; some are neighbouring ZIPs along the county line. We have not audited them, and we neither correct them nor drop them, so the count you see is the count that exists.
Overlay districts are not modeled here. An overlay can change what a property allows.
Some cells in this ordinance state two outcomes without saying what separates them; those are shown with their code and their source, and not guessed at.

Built from scripts/build_reverse_index.py, generated 2026-10-11T20:59:04+00:00.