Basement finishing in Aurora often starts with a plan for guests: a bedroom, a bathroom and a sitting area for visiting family or a relative who stays for months. That's a straightforward finished basement. The confusion begins when a suite starts to look like a separate home, because Aurora's accessory dwelling unit rules are in the middle of a rewrite as of fall 2026.
This page covers where that line sits today, how the city's permit process runs, and what to settle before framing.
One City Across Three Counties
At more than 165 square miles, Aurora reaches into Arapahoe, Adams and Douglas counties. For a basement finish, the county line matters less than people expect. The City of Aurora Building Division issues residential permits, and its Permit Center sits at 15151 E. Alameda Parkway. Applications, plan submittals and inspection scheduling run online through Aurora4Biz.org.
The county line doesn't change the radon picture either. EPA's radon zone map places all three counties in Zone 1, the highest-potential category. Get a radon result before the walls close.
Guest Suite or Basement Apartment in Aurora
Here's the state of Aurora's ADU rules as reported in 2026. Today the city allows only detached ADUs, and only on alley-served lots zoned Original Aurora and in the Painted Prairie development. Each one needs a conditional use permit with a public hearing. Local reporting says nine units have been permitted since the rules took effect in 2018.
In July 2026, city council discussed allowing one ADU on every single-family detached lot, including internal units such as a basement apartment. Council directed staff to draft an ordinance. Reporting in September 2026 said plans were expected before councilmembers by December, with adoption targeted before March. Homeowners associations could still enforce stricter rules.
Guest Suite Details for Basement Finishing in Aurora
The city's own homeowner handbook names the basement finish issues it watches: egress from living areas, plus enough heat and lighting. For a guest suite, those turn into specific decisions.
- The bedroom window. A sleeping room needs an escape opening with 5.7 sq ft net clear area, at least 24 inches of clear height and 20 of width, and a sill no higher than 44 inches. Check the existing window before assuming a new cut.
- Headroom. Under the 2021 IRC, habitable basement ceilings need 7 feet, with beams and ducts allowed down to 6 feet 4 inches. A guest room under the main beam is worth measuring twice.
- Heat. A suite on the far side of the basement from the furnace needs a planned supply and return. A register cut into the nearest duct usually leaves it cold.
- The bathroom. Its location sets drain routing and whether a pump is involved, so settle it before the rest of the layout.
How Aurora's Permit Process Runs
- Contact the Building Division for its basement finish building guide.
- Submit a plan showing the existing basement and the rooms to be finished. Staff review it against the adopted codes.
- Pay for the permit. Work can't start before it's issued, and the permit plus any stamped approved plans stay on site.
- Request inspections at least a day ahead. Aurora also offers free inspector consultations during construction.
- Close the permit at final approval.
Two timing rules matter. An Aurora permit expires if work doesn't begin within six months or isn't finished within a year, though it can be renewed or extended. And the city asks owners to hire only Aurora-licensed contractors, which you can check through its contractor lookup.
For the bigger picture, see our basement finishing services or basement remodeling in Aurora for a lower level that's already finished. Compare rules next door in Centennial basement finishing and basement finishing in Denver.
