Cobb County homeowners could soon build backyard rental units under a package of code changes heading to public hearings Tuesday, Oct. 13, and Tuesday, Oct. 27.

The proposals also include a new affordable housing incentive program, student housing density caps, tighter property maintenance rules and an updated definition of who can live in a single-family home. The Cobb Planning Commission already held a hearing on the zoning portions Oct. 6.

The Board of Commissioners will hold its first hearing at 9 a.m. Oct. 13 and a second at 7 p.m. Oct. 27, when commissioners are also scheduled to vote. Both hearings take place in the second-floor meeting room at the David Hankerson Building, 100 Cherokee St., Marietta.

The proposals are outlined in a county explainer published Oct. 8.

ADUs return after 2024 defeat

The most debated piece would allow accessory dwelling units (ADUs) in single-family residential zones. Each ADU would require a special land use permit approved by the full commission. Properties would still have to meet setback and impervious-surface limits.

Cobb tried to pass ADU language in 2024, but the Board of Commissioners withdrew the proposal at its Nov. 12, 2024, meeting after public backlash. The Planning Commission had voted to deny approval to allow more time for review.

At least two commissioners have voiced skepticism. District 3 Commissioner JoAnn Birrell told the Marietta Daily Journal in September she does not support the proposal as written, citing enforcement and setback concerns. District 1 Commissioner Keli Gambrill said she worries ADUs would crowd neighborhoods without meaningfully addressing affordable housing.

Community Development Director Jessica Guinn told commissioners at a Sept. 22 work session that the special land use permit process would give the board case-by-case review over each ADU application. "Since it's a zoning process, you all get to review every request on its own merits as a special land use permit," Guinn said, according to the Marietta Daily Journal.

The Powers Ferry Corridor Alliance, an East Cobb civic group, has published its own analysis of the amendments and is urging residents to contact commissioners before the hearings.

Housing Incentive Program

A new Housing Incentive Program would target residential developments of at least 50 units with a minimum $10 million real-property investment. At least 20 percent of units would need to be affordable to households earning up to 80 percent of Area Median Income (AMI), as determined by the U.S. Department of Housing and Urban Development. Qualifying projects could receive fee reductions or waivers on building permits and expedited plan review. Affordable units would have to stay affordable for the length of the incentive period.

Student housing, occupancy and other changes

The package sets density standards for purpose-built student housing. Projects would need a special land use permit, must sit in areas designated for Regional Activity Center future land use and would cap density at 60 units per acre, with two bedrooms counted as one unit. A traffic impact study would be required.

The proposals would also update the definition of a single-family dwelling. Under the change, a single-family home could be occupied by one family including up to three unrelated adults, or by up to four unrelated adults and their children or grandchildren.

Proposed property maintenance rules would ban invasive vines from crossing property lines, prohibit outside storage and junk vehicles on developed lots and require homeowners to maintain the right-of-way between their property line and the curb. Violators would get 20 calendar days to fix the problem before the county could issue a citation or remedy the condition at the owner's expense.

The overnight parking limit for vehicles outside a garage or carport would rise from four to five on lots in common residential zones including R-20 and R-30.

None of the amendments have been adopted. The full text of the proposed changes is available on the county's website. Residents who want to weigh in can attend the Oct. 13 hearing at 9 a.m. or the Oct. 27 hearing at 7 p.m.