The R-20 zone is Alexandria's lowest-density residential district, requiring 20,000 square feet per lot -- roughly half an acre. It is concentrated in the western and southwestern parts of the city. Large lot sizes give R-20 the most subdivision potential of the low-density zones, though substandard lot development requires SUP approval. Despite the low-density character, two-unit dwellings and multi-unit dwellings up to four units are permitted by right (Sec. 3-102). ADUs are permitted under Sec. 7-203.
Development standards in R-20
Maximum FAR
0.25
Maximum height
30 ft
Minimum lot size
20000 sq ft
Minimum lot width
100 ft
Side setback
12 ft
Rear setback
12 ft
Sec. 3-106(B): the maximum permitted floor area ratio shall be 0.25.
Sec. 3-106(C): 30 feet, rising to 40 feet for a church or school use.
Read from City of Alexandria Zoning Ordinance, effective through 2025-06-14. Amendments adopted after that date (most recent 2026-03-14) are not yet reflected.
Permitted uses in R-20
AllowedSingle-unit dwelling Sec. 3-102(A)
AllowedTwo-unit dwelling Sec. 3-102(A.1)
AllowedMulti-unit dwelling up to four units Sec. 3-102(A.2)
AllowedAccessory uses, as permitted by section 7-100 Sec. 3-102(B)
AllowedChild or elder care home, as permitted by section 7-500 Sec. 3-102(C)
AllowedChurch Sec. 3-102(D)
AllowedHome occupation, as permitted by section 7-300 Sec. 3-102(E)
AllowedPublic park Sec. 3-102(F)
AllowedPublic school Sec. 3-102(G)
AllowedUtilities, as permitted by section 7-1200 Sec. 3-102(H)
ConditionalDay care center within a church or school building Admin approval required (Sec. 11-513); Sec. 3-102.1(A)
ConditionalChild or elder care home, other than pursuant to section 3-102 Admin approval required (Sec. 11-513); Sec. 3-102.1(B)
ConditionalCemetery Special Use Permit required; Sec. 3-103(A)
ConditionalNoncommercial, not-for-profit facilities, including indoor and outdoor recreational facilities and community centers, designed to serve the neighborhood Special Use Permit required; Sec. 3-103(B)
ConditionalPrivate school Special Use Permit required; Sec. 3-103(D)
ConditionalSeminary, convent and monastery Special Use Permit required; Sec. 3-103(E)
ConditionalAny church or school parking added after October 1, 1996 which exceeds the number of spaces required by this ordinance; provided, however, that no special use permit for such excess parking shall regulate or substantially burden any religious practice or belief Special Use Permit required; Sec. 3-103(F)
AllowedADU / Accessory Dwelling By-right accessory use; Sec. 7-100(N)/7-203 standards (accessory to single/two/townhouse dwellings)
ConditionalSTR - Short-Term Rentals STR permit required for >10 days/year; owner-occupied or unhosted permitted; Sec. 7-1403/7-1404
"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.