Atlanta Zoning | By Unit Count
Where Atlanta Allows Duplexes, Triplexes and Fourplexes in 2026
This page sorts Atlanta's rules by the number of homes you want on one lot. For two homes, three and four, it answers the same four questions: which zoning district permits the building today, what approval you need if your lot is in another district, which building code applies, and what the proposed zoning rewrite would change. The current rules come from the City Code as updated September 24, 2026. The rewrite, ATL Zoning 2.0, is not adopted.
Two, three and four homes in six facts
- A duplex is a permitted use in Atlanta's R-5 district on a lot of 7,500 square feet with 50 feet of frontage, at a floor area ratio of 0.60. Source: Atlanta Zoning Ordinance, Chapter 7
- Atlanta's code defines a multi-family dwelling as a building containing three or more dwelling units, so a triplex needs a district that permits multi-family dwellings. Source: Atlanta Zoning Ordinance, Sec. 16-29.001(10)
- In the MR-MU district "an individual lot may not contain less than four nor more than 12 dwelling units," so a triplex cannot use MR-MU and a fourplex can. Source: Atlanta Zoning Ordinance, Sec. 16-35.011
- No variance may be granted for a use that the Zoning Ordinance prohibits, so an extra home in a district that bars it needs a rezoning. Source: Atlanta Zoning Ordinance, Sec. 16-26.003
- Georgia's residential code covers detached one- and two-family dwellings and townhouses of up to three stories. Other residential buildings follow the building code. Source: Georgia DCA, 2027 codes and amendments
- In 2025 the City of Atlanta issued permits for 78 two-unit buildings and 64 buildings of three or four units. Source: Census Building Permits Survey
The Whole Answer in One Table
| Homes | Building | Districts that permit it today | Approval | Georgia code that applies | ATL Zoning 2.0 draft (proposed) |
|---|---|---|---|---|---|
| 2 | House plus a detached accessory dwelling unit (ADU) | R-4, R-4A, R-5 | A building permit in those districts. A rezoning elsewhere. | Residential code | ADUs attached or detached, up to 850 sq ft each, with the number set by use district |
| 2 | Duplex or two-family dwelling | R-5. Also RG, R-LC, MR and MRC | A building permit in those districts. From R-1 to R-4B, a rezoning ($500 to R-5 for 1 acre or less). | Residential code. State law bars a sprinkler mandate for buildings of up to two homes. | Two homes per lot in the N2B, N3B and N4B districts |
| 3 | Triplex | RG, R-LC, MR-1, MR-2 and higher MR districts, MRC | A rezoning from any R-1 to R-5 lot. A variance cannot add the use. | Building code, unless built as townhouses with 2-hour fire walls | Up to six homes per lot in N5A |
| 4 | Fourplex | MR-MU, RG, R-LC, MR-1, MR-2 and higher MR districts, MRC | A rezoning from any R-1 to R-5 lot ($500 to MR-MU for 1 acre or less). | Building code, unless built as townhouses with 2-hour fire walls | Up to six homes per lot in N5A and twelve in N5B |
Sources: Atlanta Zoning Ordinance Chapter 7, Chapter 8, Chapter 35 and Chapter 26; City Code Sec. 6-1007; Georgia DCA code amendments; ATL Zoning 2.0 Draft V2, Chapter 2.
One definition explains the jump between two homes and three. Atlanta's definitions chapter says a multi-family dwelling is "a building containing three or more dwelling units." Two homes can be a duplex or a two-family dwelling, which R-5 permits. A third home makes the building multi-family, and no district from R-1 to R-5 permits that use.
Two Homes: Duplex, Two-Family Dwelling or House Plus ADU
Which district permits it
R-5, the Two-Family Residential district, lists a "single-family or two-family dwelling" as its first permitted use. The code separates two kinds of two-home building. A duplex is two homes that share a vertical wall, with each home facing the street, or two homes on more than one floor of the same structure. A two-family dwelling is a building with two homes that does not meet the duplex definition. The difference matters for floor area. Floor area ratio is the floor area of the building divided by the area of the lot. A duplex may reach a ratio of 0.60 of net lot area. In a two-family dwelling, the main home is held to 0.50 and the second home may not exceed 750 square feet.
The R-5 lot must have 7,500 square feet and 50 feet of frontage. The yards are 30 feet in front and 7 feet at the sides and rear. Coverage may reach 55 percent of net lot area, and the height limit is 35 feet. Parking is one space per home where one home is 750 square feet or less; otherwise it is one space per home with up to three bedrooms, plus one for each bedroom above three. An R-5 lot of record smaller than 7,500 square feet may still hold a two-family dwelling or a duplex.
R-4 and R-4A offer a narrower kind of second home: one detached accessory dwelling unit (ADU) of up to 750 square feet behind or beside the house. The ADU page covers it. RG, R-LC and the MR districts also permit two-family dwellings.
What approval it needs
On an R-5 lot that meets the lot rules, a duplex is a permitted use, so the approval is a building permit. Two extra approvals can apply by location. A lot in a historic or landmark district needs a certificate of appropriateness for a new building. A lot inside the BeltLine Overlay that is immediately adjacent to the BeltLine Corridor needs a special administrative permit.
On an R-1 to R-4B lot, a duplex needs a rezoning to R-5. The application fee in Section 6-1007 is $500 for a site of one acre or less. A variance cannot add the second home. The variance chapter says "no variance may be granted for a use of land or building or structure that is prohibited by the Zoning Ordinance."
R-5 also lets the two homes sit on separate lots through zero-lot-line development, which means homes built up to a shared lot line. A single lot may be 2,500 square feet where the combined area is at least 7,500 square feet. Dividing a lot with an existing two-family dwelling this way needs a special administrative permit.
Which building code applies
Georgia's residential code is the International Residential Code with Georgia amendments. Its scope covers "detached one- and two-family dwellings and townhouses separated by a 2-hour fire-resistance-rated wall assembly, not more than three stories above grade plane in height with a separate means of egress." A duplex is a two-family dwelling, so it is designed under that code.
State law also limits sprinkler rules for these buildings. The Georgia amendments to the residential code quote O.C.G.A. 8-2-4: no state or local residential code adopted after May 24, 2010 "shall include a requirement that fire sprinklers be installed in a single-family dwelling or a residential building that contains no more than two dwelling units."
What the draft proposes
Proposed only: ATL Zoning 2.0 Draft V2 would allow two homes per lot in three districts, N2B (7,500 square foot lots, floor area ratio 0.60), N3B (5,000 square feet, 0.65) and N4B (2,800 square feet, 0.70). Its districts H1 to H6, N1, N2A, N3A and N4A would stay at one home per lot. The draft's parking table sets one space per home for up to two homes in Parking Zone 3 and no minimum in Parking Zones 1 and 2.
Three Homes: The Triplex
Which district permits it
A triplex is a multi-family dwelling under the code, so it needs a district that permits multi-family dwellings. Those are RG (Residential General), R-LC (Residential-Limited Commercial) and the MR districts. MRC, the mixed residential commercial district, permits housing too.
The numbers differ by district. In RG, floor area comes from a table by sector, and the highest ratio is 0.348 in Sector 2 and 0.696 in Sector 3. MR-1 has a ratio of 0.162 and MR-2 of 0.348, each on a lot of at least 2,000 square feet with 25 feet of frontage and a 35-foot height limit. R-LC multi-family buildings follow the Sector 2 ratios.
MR-MU is the exception among the MR districts. It says "an individual lot may not contain less than four nor more than 12 dwelling units." Three homes are under that minimum.
What approval it needs
On land already zoned RG, R-LC or MR, a triplex that meets the district rules needs a building permit. From an R-1 to R-5 lot it needs a rezoning. The steps are an application, a staff report to the Zoning Review Board, a public hearing, a recommendation to the City Council's Zoning Committee and a Council vote, with the Neighborhood Planning Unit's recommendation sent to Council. The fee to RG or MR is $500 for one acre or less, and $1,000 more if the Comprehensive Development Plan land use map must change. Under Georgia's HB 155 (2025), a property whose rezoning is denied cannot be considered again for at least six months. The approvals page explains each step.
Which building code applies
The residential code covers only one- and two-family dwellings and townhouses. A three-home building that is not townhouses is therefore built under the Georgia building code, which is the International Building Code with Georgia amendments. The state's building code amendments repeat the rule: their first exception sends one- and two-family dwellings and townhouses to the residential code. The sprinkler statute quoted above stops at two homes, so it does not cover a triplex.
The edition matters too. On December 9, 2025 the Georgia Department of Community Affairs announced that its Board adopted the 2024 International Residential Code and the 2024 International Building Code with Georgia amendments, "with an effective date of January 1, 2027." Confirm with Atlanta's Office of Buildings which edition applies to a permit you file before that date.
What the draft proposes
Proposed only: Draft V2 has no district capped at three homes. Its N5A district would allow up to six homes on a lot of at least 2,000 square feet, with no floor area ratio and a height of 2.5 stories or 35 feet. Above two homes, the draft's parking table sets no minimum in any parking zone.
Four Homes: The Fourplex
Which district permits it
Four homes is where MR-MU starts. The City added the district by Ord. No. 2019-09 on January 31, 2019, and the code describes it as "Two- to three-story multi-unit buildings targeting 'Missing Middle' housing needs." Missing middle housing means buildings between a house and a large apartment block in size. The MR-MU rules:
- at least four and at most 12 homes on a lot, and at most 12 in a building;
- one principal building per lot;
- a lot of at least 2,000 square feet with 25 feet of frontage;
- side yards of 5 feet and a rear yard of 10 feet;
- a height limit of 35 feet;
- a minimum of 0.5 parking space per home;
- no commercial uses, and no attached homes on separate lots.
RG, R-LC, MR-1 and MR-2 permit a fourplex too, under the floor area ratios given above for a triplex.
What approval it needs
The approval steps are the same as for a triplex. From an R-zoned lot, a fourplex needs a rezoning, and the application fee to MR or MR-MU is $500 for one acre or less. Atlanta's affordable housing rules start at ten homes: the BeltLine and Westside rules apply to developments of ten or more new rental homes, and the Northwest Atlanta overlay to ten or more new rental or for-sale homes. A fourplex is under that threshold. The BeltLine page explains them.
Which building code and fees apply
A fourplex that is not townhouses is built under the Georgia building code, like a triplex. Impact fees are one-time charges on new homes for roads, parks, fire and police. Atlanta's impact fee chapter defines "Multifamily" as "all residential dwelling unit types other than single-family detached dwelling units," so each home in a duplex, triplex or fourplex is charged at a multifamily rate. The 2020 study the City adopted lists $2,961 per home in a multifamily building of one or two stories and $2,524 per home in a building of three to ten stories.
Loans change at three and four homes as well. The Federal Housing Administration (FHA) applies a self-sufficiency test to three- and four-unit properties: the monthly payment of principal, interest, taxes and insurance may not exceed 100 percent of the net rental income the appraiser estimates. The 2026 conforming loan limit for a four-unit property in Fulton and DeKalb counties is $1,601,750. See financing 2 to 4 units.
What the draft proposes
Proposed only: a fourplex would fit the draft's N5A district (up to six homes) and N5B district (up to twelve homes, 3 stories or 35 feet), each on a lot of at least 2,000 square feet. The draft also says a lot within a half mile walking distance of a high-capacity transit station may use the Parking Zone 1 rules. Ordinance 26-O-1508 was held in the Zoning Committee on September 14 and September 28, 2026. The ATL Zoning 2.0 page has the full table.
No Transit Rule Adds Homes Today
The current code has no rule that allows duplexes or fourplexes near MARTA stations in single-family districts. The history notes under the R-1 to R-5 and RG chapters end in 2021, and no ordinance from 2022 to 2026 changed the number of homes those districts allow. The zoning amendments adopted from 2024 to 2026 deal with other subjects, such as data centers, party houses, storage facilities in the BeltLine Overlay and an affordable housing density bonus in the MRC-3 district.
The one transit benefit in the current code is a fee reduction. Under Section 19-1009 of the City Code, the transportation part of the impact fee is cut 50 percent for a project within 1,000 feet of a MARTA station, measured along a legal and practical walking route, if its parking does not exceed any required minimum and is no more than 80 percent of any maximum.
How Many Are Being Built
The Census Bureau counts building permits by the number of homes in each building. In 2025 the City of Atlanta permitted 78 two-unit buildings, up from 51 in 2024, and 64 buildings of three or four units, down from 98. The whole metro area permitted 94 two-unit buildings and 98 buildings of three or four units in 2025.
| Building permits | 1-unit buildings | 2-unit buildings (homes) | 3 to 4 unit buildings (homes) | 5+ unit buildings (homes) |
|---|---|---|---|---|
| City of Atlanta, 2025 | 561 | 78 (156) | 64 (236) | 388 (4,669) |
| City of Atlanta, 2024 | 791 | 51 (102) | 98 (369) | 590 (6,847) |
| Atlanta-Sandy Springs-Roswell metro area, 2025 | 22,065 | 94 (188) | 98 (365) | 585 (11,052) |
| Georgia (statewide), 2025 | 44,351 | 354 (708) | 176 (641) | 814 (15,496) |
Sources: Census Bureau Building Permits Survey annual files for places, 2025, places, 2024, metro areas, 2025 and states, 2025.
Best For
- ✓ A duplex on an R-5 lot of 7,500 square feet or more, where the approval is a building permit.
- ✓ A fourplex on land already zoned MR-MU, with 0.5 parking space per home and a 35-foot height limit.
- ✓ A triplex on RG, R-LC, MR-1 or MR-2 land, where multi-family dwellings are a permitted use.
Usually Fails When
- ✕ The plan is a triplex on MR-MU land. The district requires at least four homes on a lot.
- ✕ The owner applies for a variance to add a home. A variance cannot grant a prohibited use.
- ✕ The budget for a three-home building assumed the residential code and no sprinkler review.
What To Verify Before Spending Money
- → The district on the Atlanta Property Information map, and for RG land the sector number.
- → With the Office of Buildings: the code edition that applies on your filing date.
- → The status of ordinance 26-O-1508 before you rely on any proposed district.
Where to Go Next
Related on VanPlex: the Atlanta multiplex guide overview, the Texas building code page and the missing middle guide.
Frequently Asked Questions
Where can I build a duplex in Atlanta?
Can I turn my single-family house into a duplex in Atlanta?
What lot size do I need for a duplex in R-5 in Atlanta?
Can I build a triplex in Atlanta?
What zoning do I need for a fourplex in Atlanta?
Can I get a variance to build a duplex in R-4 in Atlanta?
How do I rezone my Atlanta lot to R-5 or MR-MU?
How much does a rezoning application cost in Atlanta?
Can each side of a duplex be sold separately in Atlanta?
How much parking does a duplex need in Atlanta?
Does a triplex need fire sprinklers in Georgia?
Are duplexes allowed near MARTA stations in single-family zones in Atlanta?
Official sources (checked October 2026)
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