This Week in Metro Atlanta: Cobb Is One Vote From Legalizing the Backyard Unit

Three things moved in Metro Atlanta over the past week, and each one carries a date. One would change what you are allowed to build on land you already own. One put a shovel in the ground on a trail that has been moving prices around it for fifteen years. And one finally tells Fulton homeowners when the real tax bill shows up.

Start with Cobb, because almost nobody is talking about it and it touches the most ordinary homeowners. A package of zoning code amendments is moving through hearings in Cobb County, and inside it is language that would allow accessory dwelling units in unincorporated Cobb. The proposed terms, as reported by East Cobb News on September 8: an ADU of up to 850 square feet or 50 percent of the main dwelling, single story, connected to the main building’s meter, with at least one off-street parking space. The owner has to live on the property. Short-term rental is prohibited.

Read those last two conditions twice, because they are the whole ballgame. Owner-occupancy plus a short-term rental ban means this is not an Airbnb ordinance. It is a long-term rental and multi-generational housing ordinance. If it passes, a Cobb homeowner with a usable back yard gets a second legal dwelling that can hold a parent, an adult kid, or a twelve-month tenant. What that does to the property is not theoretical: it adds an income stream an appraiser can eventually see, and it adds a buyer pool that cannot afford two houses but can afford one with a unit behind it. The 850-square-foot ceiling and the single-story rule keep it modest, and the shared-meter requirement means you are not quietly creating a duplex. The hearings are October 6 and October 13 at 9 a.m., and the final hearing and vote on all the code amendments is October 27 at 7 p.m. If you own in unincorporated Cobb, put October 27 on the calendar. Zoning changes that make your lot more useful rather than less are rare enough to show up for.

The same package handles data centers, which is the reason it exists. Cobb commissioners voted in August to extend the county’s moratorium on new data center rezonings and permits in unincorporated Cobb by six months, out to February 24, 2027, specifically to buy time to write rules. The proposed rules: a five-acre minimum and a thirty-acre maximum, power generated off-site, closed-loop cooling with no discharge into county wastewater outside routine maintenance, plus noise limits on cooling systems and backup generators and restrictions on lighting and building height. If you own acreage in Cobb and a data center broker has been calling, the thirty-acre cap is the number that matters. It decides who can assemble what, and for now it takes the very large speculative plays off the table in unincorporated Cobb.

Second, the Beltline. On September 10 the Atlanta Beltline broke ground on Northwest Trail Segment 3B, roughly a mile of trail running from Trabert Avenue to Tanyard Creek Park and tying into the already-completed Segment 3A. It includes a pedestrian bridge over Northside Drive and an elevated stretch that passes under I-75 along the Tanyard Creek channel. The neighborhoods it touches are Ardmore, Berkeley Park, Brookwood, Collier Hills and Loring Heights, with Rough Draft Atlanta also naming Underwood Hills and Channing Valley. Mayor Dickens put the mainline at 78 percent complete, 16.7 of 22 miles, with the northern corridor targeted for 2030. Urbanize Atlanta reports the segment is expected to open in late fall 2028. I am not going to tell you a groundbreaking is a buy signal, because the premium on Beltline-adjacent property usually gets priced in somewhere between the announcement and the ribbon cutting, and this segment was announced a long time ago. What a groundbreaking does is remove risk. It converts “planned” into “funded and under construction,” which is the point where lenders and appraisers start treating proximity as real. If you are shopping Collier Hills or Berkeley Park, you are not early anymore, but you are buying a two-year construction window instead of a ten-year maybe. Different bet, not a bad one — just underwrite the noise and the closed sidewalks for the next two summers.

Related and further out: on September 7 the Beltline released its recommendations for the $3.5 billion light rail plan, endorsing the CSX alignment on the grounds of fastest average speed and lowest travel time, direct service to Piedmont Hospital, lowest capital cost and highest ridership. The recommendation covers 13 station locations across the southwest and southeast corridors, from Donald Lee Hollowell Parkway to Glenwood Avenue, with three bi-directional routes running about 18.5 hours a day and a conservative projection of 4.2 million annual riders. Public comment is open through November 3. If you own on the southwest or southeast side, that comment window is the cheapest influence you will ever have over what gets built next to you, and it closes whether or not you use it.

Third, a short follow-up to last week. Fulton’s temporary tax bills — the ones mailed August 15 on preliminary 2026 valuations paired with 2025 millage rates — now have a sequel date. The Board of Assessors finished valuations on September 1, the Tax Commissioner’s office began reconciling the figures on September 2, and corrected bills are expected in mid-November. None of that changes what you owe right now. City of Atlanta taxes are due September 30, Fulton County and the other jurisdictions October 15, and you pay the provisional number on time regardless of the fact that it can still move.

So: three dates. September 30 and October 15 if you own in Fulton. October 27 if you own in unincorporated Cobb and a legal backyard unit would change your math. November 3 if you have an opinion about Beltline rail on the south side. For background on everything else, the most recent Atlanta REALTORS Market Brief is still July — a $445,000 median, up 2.1 percent year over year, with 4.7 months of supply and homes averaging 24 days on market. That is a balanced market with a slow pulse, and in a market like that a zoning change or a construction start moves an individual property far more than the headline number does. If you want to know which of these three actually touches your address, send it to me and I will tell you straight.