Basement finishing in Centennial runs through the city's Building Division at the Civic Center on East Arapahoe Road, and the city spells out what it wants in a nine-page Single Family Basement Finish checklist. Submittals missing required items are treated as incomplete and won't be reviewed, which is reason enough to plan from that checklist.
Centennial was incorporated in 2001 from parts of unincorporated Arapahoe County. A 2023 city housing report found that around three-fourths of its homes are single-family detached and that residents are, on average, older than the statewide population, with more people aging in place. Plenty of those houses have a basement that could be doing more.
What Centennial's Basement Checklist Asks For
The application can be filed online. Behind it, the city wants a floor plan with these details:
- Existing basement dimensions, plus dimensions of every new room, new opening and relocated item.
- Window sizes and types, with emergency escape windows and well sizes clearly marked.
- Plumbing changes, and the furnace and water heater locations.
- Any change to posts, beams or joists. A registered engineer's plan or letter may be required.
- Every area where the ceiling is lower than 7 feet.
A plan or letter from a registered engineer is required for any new opening in the existing foundation wall or a bearing wall. Two outside agencies can enter the picture: South Metro Fire Rescue reviews suppression plans for homes with fire sprinklers, and Arapahoe County Public Health must approve new basement bedrooms on a septic system.
Ceiling Heights for Basement Finishing in Centennial
Low ductwork and beams decide more basement layouts than taste does. Measure them first.
A ceiling that clears code can still feel tight in a theater or a gym. We'd rather know the exact clearance under the main beam on day one than discover it after the soffits are framed.
Planning a Home Gym Below Grade
The city's checklist touches a fitness room in a few places.
- Light and air. Natural light and ventilation are required in all finished parts of the basement, usually through an operable window or door. Where that isn't possible, mechanical ventilation and artificial light are required.
- Outlets. No point along the floor line of any wall can be more than 6 feet from a receptacle, and hallways 10 feet or longer need one. GFCI protection follows the IRC.
- Overhead room. Code minimums aren't lifting standards. Stand where a rack or treadmill will go and check the clearance with your arms raised.
The slab matters too. The Colorado Geological Survey lists cracked and heaved basement floor slabs as a common sign of expansive clay, and it advises allowing for floor movement in known swelling-soil areas. Rubber gym flooring can float over minor slab movement. Equipment bolted to both the slab and the wall framing can't, so we'd keep heavy anchors to one or the other.
Inspection Points That Catch Centennial Projects
- A smoke detector close to the basement stairs, plus one in and outside any new sleeping room. Adding a bedroom brings the whole house up to new-home smoke alarm rules.
- Furnaces and water heaters can't sit in or be reached through a bedroom or bathroom unless they're direct vent, and they need 30 inches of clear working space in front.
- Fireblocking at the ceiling line and every 10 feet along furred walls, with the manufacturer's documentation for your chosen method in the submittal.
- R-19 cavity or R-15 continuous insulation on perimeter walls.
- Half-inch drywall inside any usable space under the stairs.
- An egress window under a deck needs a clear path at least 36 inches high leading outside.
Radon and Long-Term Use in Arapahoe County
Arapahoe County sits in Zone 1 on EPA's radon map, and EPA's advice is to test every house no matter the zone. Run that test before framing, so a mitigation pipe, if one is needed, goes in while the studs are still exposed.
If you plan to stay put, a lower level with a bathroom and an egress-compliant room keeps options open. That's the thinking behind our basement finishing services. If your basement was finished decades ago, basement remodeling in Centennial often starts with the same checklist items. Compare how nearby cities handle it in Lone Tree basement finishing and basement finishing in Aurora.
