Allow attached ADUs, for sale option and expand citywide

What are “Accessory Dwelling Units” or “ADUs”?

Accessory Dwelling Units (ADUs), also called basement apartments, granny flats, carriage houses and garage apartments, are small residential units that are accessory to the main dwelling unit. ADUs can be attached to the main dwelling unit, such as with the conversion of a basement or attached garage into a dwelling unit. They can also be detached, that is, constructed as a separate smaller dwelling unit located on the same parcel as the main housing unit. Detached ADUs are currently allowed in R4, R4A, R5, and several of the city’s SPIs and historic districts.

What would the proposed ordinance do?

The ADU proposal would expand the types and designs of ADUs that can be constructed in the city and the areas where they can be built. The proposal includes a variety of clean-ups and improvements on the 2018 ADU ordinance that was part of the Zoning Quick Fix effort. The changes include tweaks to the size and setback restrictions on ADUs, the ability to attach the ADU to the primary dwelling, and the zoning districts where ADUs can be constructed.

The ordinance:

• Allows ADUs to be attached to the main dwelling like a basement apartment or garage conversion (maximum size: 50% of main or 1000 square feet)

• Increases detached ADU height from 20 ft to 24ft to allow second floor and over garage

• Adds ADU allowance to the R4B district (1 ADU max)

• Changes ADU rear and side setback in R4, R4A, R4B to 4ft (already allowed in R5)

• Increases detached ADU size allowance from 750 sqft to 1000 sqft.

• Allows for the sale of ADUs through detached zero-lot-line configuration currently used for duplexes in R5. This would not be a formal subdivision. This process allows for separate ownership of the units but maintains the existing development controls on the whole lot.

• Updates for-sale ADU language to claidy that only 1 zero-lot-line is allowed per lot

• Allows 3 total units in R5: i.e. duplex + ADU or 1 family unit + 2 ADUs

• Updates code to include ADUs in total floor area ratio calculation

• Only count conditioned space toward ADU square footage allowance (currently, garage space counts against the unit sqaure footage allowance for ADU which limits the ability to build a unit-over-garage style of ADU)

What would the proposed ordinance not do?

The proposed ordinance would amend the types of configuration options for ADU construction in R4-R5 options, but would not substantially change the allowable uses already allowed in these districts (except for adding ADU allowance in R4B). The main function of this portion of the ordinance is to make ADUs easier and more affordable for home owners to build and for residents to live in. Currently ADU allowance is limited to detached structures which differs from many other U.S. cities and Atlanta’s own history of allowing a broader diversity of secondary units like basement apartments. This element of the ordinance seeks to bring greater flexibility to homeowners to use their property in a variety of ways to construct accessory dwellings.

The proposed ordinance would only allow a single ADU to be built on parcels that contain a main, single-family, stand-alone home in R4, R4A and R4B districts. In R-5 districts, three total units would be allowed such as a duplex plus an ADU OR a single-familiy home plus two ADUs. The proposal does not impact or allow for the construction of any other type of housing structure that is not already permitted. For example, the proposed ordinance would not allow for large, multi-family apartment buildings to be constructed in neighborhoods that are currently zoned exclusively for single-family homes.

The ADU element of the ordinance does not propose allowing ADUs in the city’s R1-R3 single-family districts. The original proposal in Atlanta City Design Housing proposed an expansion to these areas, but after receiving extensive feedback from residents in the neighborhoods where R1-R3 zoning exists we determined that these communities were not ready to add an ADU allowance to their zoning districts. The R1-R3 zoning districts make up approximately 17% of Atlanta’s 1- and 2-family lots and are much larger and more suburban in nature (R1 lots have a 2 acre minimum lot size) than the R4-R5 lots that constitute the other 83% of the 1- and 2-family lots in the city. We plan to continue discussions with residents in R1-R3 areas of the city as we look for opportunities to appropriately expand affordable options throughout the whole city.

How would for-sale ADUs work?

ADUs could allow for ownership by using a provision in the zoning code called 'zero'-lot-line'. This is currently used in the R5 district to allow each side of a duplex to be sold separately. It allows each of the units to be separated for ownership purposes only, but keeps the existing controls on the parcel.

• Zero-lot-line allows for separate ADU ownership but the original 'parent lot' development controls still govern the whole property.
• It is NOT a formal subdivision.
• This is already used regularly in R5 for duplexes in Atlanta.
• Allowing zero-lot-line for detached ADUs would:
  • Make ADU construction easier to finance (because the ADU could be collateralized)
  • Create more affordable ownership opportunities

Is there a map available showing the zoning districts impacted by the proposed ADU changes?

Yes! The map below shows the zoning districts impacted by the proposed ADU changes.

The above map "Districts Impacted by ADU Proposed Changes" is meant to provide a broad overview of the impact of ADU zoning changes throughout the city. The impacted parcels were estimated by geographically intersecting the zoning districts in the City of Atlanta with the parcels in the City of Atlanta. In some cases, parcels are geographically within multiple zoning districts either because they truly are, or because there are slight imprecisions in the spatial data. This means that there is some margin of error in this map, although we estimate that it is small. If you find a parcel you believe was assigned in error in this map, please contact housing@atlantaga.gov

What are the current regulations regarding ADUs in Atlanta?

In Atlanta, detached ADUs currently can be constructed “by-right” (meaning without a zoning variance) in R4, R4A, and R5 of zoning districts (as well as a few SPIs and historic districts). To-date, there has been limited development of detached ADUs in the city. The proposed changes aim at making the ADU code work better for homeowners looking to leverage their property to build an ADU.

How do Atlanta’s ADU regulations compare with other U.S. cities?

Atlanta differs from most U.S. cities that have allowed ADUs by not currently allowing the accessory unit to be attached to the main dwelling. This limits the type of ADUs that can be built to the more expensive detached option. Many of the cities that have allowed ADUs in recent years have seen the majority of their ADU development come in the form of conversion or expansion of existing space through attached ADUs. This is often more practical and affordable for homeowners. For instance, in Los Angeles, nearly four out of every five ADUs are conversions or expansions of existing space. Only one in five are detached ADUs.

Is there desire from the public for these changes?

Beginning in the summer of 2018, the Department of City Planning led multiple public engagement sessions about the current housing situation and listened to residents, affordable housing advocates, and other stakeholders about the pressing need to create affordable housing opportunities in Atlanta while retaining the unique characteristics of the city’s neighborhoods. The proposals in ACD Housing, including the ADU expansion proposal, has been drafted with that specific goal in mind. The proposed changes to the zoning code are intended to allow for an increase in housing options across the income spectrum throughout the city in a way that intentionally preserves the unique neighborhood-focused development pattern of Atlanta.

What impact could new ADU options have for Atlanta?

ADUs increase the diversity of housing options for residents by providing the opportunity for smaller homes on the lot of larger ones. This can be helpful for multigenerational living, increasing low-cost housing in the City, increasing the economic diversity of neighborhoods, and adding gentle density to single-family neighborhoods. Simply put, ADUs give residents more housing choices. A study of three cities that expanded their ADU allowances found that a majority of ADUs were used as for primary residence and only 12% were used for short term rentals. Further, of those who rented their ADUs, about 60% did so at below market-rate, demonstrating that ADUs can provide an affordable housing option. Additionally, of the ADUs for rent: 58% of homeowners rent their ADUs below the market rate (Chapple, Wegmann, Mashhood & Coleman, 2017).

I’m worried that the proposed expansion of ADUs will negatively impact the character of my neighborhood and have other negative impacts. Should I be?

ADUs are a way of adding “gentle density” to residential neighborhoods – adding additional housing options in a way that preserves residential character while also allowing greater access, especially to groups that historically have been excluded as a direct result of racially restrictive zoning policies.

It should also be noted that 2- and 3-family housing already exists across the city in neighborhoods that are currently zoned exclusively for single-family homes. At least 2,418 2 and 3 family housing units already exist today in single-family zoned neighborhoods such as Atkins Park, Virginia Highland, Morningside, Lenox Park, West End, Grove Park, Adair Park and others.

For a variety of reasons, 2- and 3-family housing structures are already a large part of the fabric of Atlanta’s exclusively single-family zoned neighborhoods. Creating a more flexible ADU code in much of the city, particularly by allowing them to be attached to the main dwellings would legitimize their development and expand this important housing affordability option in an equitable, inclusive, and accessible manner.