Zoning › Colorado › Arapahoe County › Aurora

Aurora, CO Zoning

Euclidean-zoning. 17 districts · 5 overlays · 5 applicable state preemptions.

Overview

Code type
euclidean
Naming convention
mixed
Naming convention by category
residentialR-R (Rural), R-1 (Low-Density), R-2 (Medium-Density), R-3 (High-Density), R-4 (Very High-Density)
mixed_useMU-N (Neighborhood), MU-C (Community), MU-OI (Office-Industrial), MU-OA (Original Aurora, 5 subdistricts), MU-TOD (Transit-Oriented), MU-A (Aurora Mixed-Use), MU-FB (Fitzsimons Boundary)
industrialI-1 (Business/Tech), I-2 (Industrial)
specialAPZ (Airport Protection Zone — functions as base district around Buckley SFB), AD (Airport District), POS (Parks and Open Space)
overlays-AIO (Airport Influence), -HPO (Historic Protection), -CPO (Conservation Parks), -NAO (Natural Areas); prefix hyphen convention

Aurora UDO (Ch. 146) is Euclidean with layered overlays. Two FM-1 traps: (1) overlay codes use leading hyphen (-AIO, -HPO, -CPO, -NAO) which is easily lost in data extraction; (2) APZ is formally a base district around Buckley SFB but functions overlay-like (AICUZ-derived use restrictions). The three-subarea system (A, B, C) produces different dimensional tables per subarea per §146-4.2.2 — Subareas A/B use Table 4.2-1 and Subarea C uses Table 4.2-2 with optional Small Residential Lot (§146-4.2.3.A) and Flexible Residential Lot Option (§146-4.2.3.B). Subarea C also has explicit du/ac caps where A/B do not. Density uses 'gross adjusted area' (§146-4.2.1.C) — excludes floodplain and publicly owned land; includes half of perimeter ROW. | naming_convention_raw=conventional-suffix-mixed-with-subarea ; sub_flags_raw=[state-preemption-heavy, mpo-tod-preempted, military-installation-aicuz, three-subarea-system]

Worth knowing
  • Three-subarea system: Aurora's UDO divides the city into Subareas A, B, and C with different dimensional standards tables per subarea. Table 4.2-1 applies to Subareas A and B; Table 4.2-2 applies to Subarea C. Subarea C (eastern growth areas) has explicit du/ac caps (R-1 = 3, R-2 = 5 per §146-4.2.3.A) plus optional Small Residential Lot and Flexible Residential Lot development forms not available in A/B. Developer using Subarea A standards in Subarea C will get wrong answers. Highest-value quirk — easily missed by practitioners. — [c§146-4.2.2 (tables); c§146-4.2.3.A (Subarea C Small Residential Lot); c§146-4.2.3.B (Flexible Residential Lot)]
  • Buckley Space Force Base / APZ: Aurora is one of few US cities with an active military installation generating AICUZ-derived APZ zones that function as a base district, not merely an overlay. APZ district has a 1 du/ac cap for residential in APZ II; APZ I prohibits residential entirely. Federal AICUZ rules (DoD) and local APZ use restrictions combine. Substantial eastern-city impact where Buckley SFB approach/accident-potential zones extend into otherwise developable parcels. Tagged as federal_state_conflict territory where state HB24-1313 density floor meets AICUZ density cap — federal floor/ceiling governs per supremacy. — [c§146-2.6.2; c§DoD AICUZ Buckley Space Force Base; zoning/us/federal-overlays/AICUZ.json]
  • ADU parking requirement effectively removed: UDO previously required each ADU have an identified parking space. Per CO HB24-1152 (by-right ADU statewide) and HB24-1304 (parking mandate waiver near transit in MPO), any parking mandate for ADUs in Aurora's DRCOG MPO 1/4-mi transit buffer is preempted. Post-2024-05-13 practical rule: no minimum parking for ADUs in transit-proximate Aurora parcels. — [c§Colorado HB 24-1152; c§Colorado HB 24-1304]

+ 6 more in Quirks & notes

Districts

mu 7spec 5res_sf 3res_mf 2
CodeNameCategory Min lotHeight CoverageFAR Du/acParking Setbacks F/S/R
R-RRuralres_sf—35 ft—[1]—[2]—[3]225 / 25 / 10
R-1Low-Density Residentialres_sf5,000 sf35 ft—[4]—[5]3220 / 5 / 20
R-2Medium-Density Residentialres_sf5,000 sf35 ft—[6]—[7]5225 / 25 / 10
R-3High-Density Residentialres_mf5,000 sf35 ft—[8]—[9]—[10]—[11]25 / 25 / 10
R-4Very High-Density Residentialres_mf5,000 sf——[12]—[13]—[14]—[15]25 / 25 / 10
MU-NNeighborhood Mixed-Usemu5,000 sf——[16]—[17]——[18]25 / 25 / 10
MU-CCommunity Mixed-Usemu5,000 sf——[19]—[20]——[21]25 / 25 / 10
MU-OIOffice-Industrial Mixed-Usemu5,000 sf——[22]—[23]——25 / 25 / 10
MU-OAOriginal Aurora Mixed-Usemu5,000 sf——[24]—[25]——— / — / —
MU-TODTransit-Oriented Developmentmu5,000 sf——[26]—[27]—[28]—[29]25 / 25 / 10
MU-AAurora Mixed-Usemu5,000 sf——[30]—[31]——25 / 25 / 10
MU-FBFitzsimons Boundary Mixed-Usemu5,000 sf——[32]—[33]——25 / 25 / 10
APZAirport Protection Zonespec———[34]—[35]1—— / — / —
ADAirport Districtspec———[36]—[37]—[38]—25 / 25 / 10
I-1Business/Tech Districtspec5,000 sf——[39]—[40]—[41]—25 / 25 / 10
I-2Industrial Districtspec5,000 sf——[42]—[43]—[44]—25 / 25 / 10
POSParks and Open Spacespec—[45]——[46]—[47]—[48]—25 / 25 / 10

Confidence: confirmed partial under review not found

Overlays

-AIO
Airport Influence Overlay
AP
§146-2.6.2

Properties within the officially designated Airport Influence District surrounding Buckley Space Force Base (formerly Buckley AFB), Denver International Airport (DEN) approach corridors, and Centennial Airport influence reach. Triggered at time of subdivision or new construction.

-HPO
Historic Protection Overlay
HP
§146-2.6.5 (formerly §146-2.6.4 in earlier UDO versions — renumbered)

Properties designated as local landmarks, landmark sites, or within designated local historic districts by the City of Aurora. Original Aurora (MU-OA) district area contains most of the city's designated historic fabric.

-CPO
Conservation Parks Overlay
COR
§146-2.5.5

Applied to portions of POS (Parks and Open Space) district by the city. Includes conservation-oriented park areas where permanent structures require conditional use approval on privately-owned POS land.

-NAO
Natural Areas Overlay
COR
§146-2.5.5

Applied to portions of POS district containing natural habitat, riparian corridors, or sensitive landscape features.

FLOOD
Floodplain Provisions
FP
§146-4.2.3.J (Plugged Wells) + §146-5 procedures + FEMA FIRM adoption

FEMA-mapped Special Flood Hazard Areas (SFHA) on Arapahoe, Adams, and Douglas County FIRM panels; primary watercourses: Sand Creek, Toll Gate Creek, Coal Creek, Murphy Creek, East and West Toll Gate Creek.

State preemptions

CO-HB24-1152-ADU-BY-RIGHTapplies
Qualifying condition
Aurora is a member of DRCOG (Denver Regional Council of Governments, the Denver metro MPO). city.is_in_mpo = TRUE. Trigger predicate (is_in_mpo OR (pop>=1000 AND is_in_connected_metro)) satisfies via is_in_mpo. Aurora pop 405,129 (Census PEP 2023 vintage) >> 1,000.
Effect
ADUs must be permitted as-of-right in all single-family residential zones. Aurora R-R, R-1, R-2 must allow ADU by-right; any owner-occupancy requirement is preempted; design standards cannot be more restrictive than those for primary structure. MU-A district explicitly notes ADUs permitted per HB24-1152 in existing research. Discretionary review waived for ADU projects.
CO-HB24-1313-TOD-DENSITYapplies
Qualifying condition
Aurora is a member of DRCOG MPO (is_in_mpo=TRUE). Aurora hosts the RTD R-Line light rail with 8 stations inside city limits plus RTD A-Line heavy-rail commuter line passing through (Peoria, 40th/Airport/Gateway-Park, 61st/Pena stations). parcel.in_transit_center_or_corridor resolved TRUE at station-area parcel level. MU-TOD base district already exists in UDO §146-4.2 indicating local TOD planning framework in place. | status_note: Under active litigation as of 2025; Aurora's compliance is partial pending judicial resolution. Bill signed 2024-05-13 with statutory compliance deadline for zoning updates; Aurora UDO has not been comprehensively amended for HB24-1313 as of Nov 2025 supplement.
Effect
Across designated transit areas (1/2 mile of rail stations and 1/4 mile of high-frequency bus stops), Aurora must allow 40 du/ac average density. Duplexes by-right in all single-family zones citywide (MPO-wide provision not limited to transit areas). R-1/R-2/R-3/R-4/MU-TOD max_units_per_acre floor_at 40. Applies despite Aurora home-rule status per statewide-concern declaration.
CO-HB24-1304-PARKING-LOT-SIZE-CAPSapplies
Qualifying condition
city.is_in_mpo = TRUE (DRCOG). parcel.within_quarter_mile_transit resolved parcel-level; Aurora RTD rail stations and high-frequency bus corridors (Colfax Ave, Havana St) generate substantial 1/4-mi transit buffer coverage. Predicate satisfies at transit-proximate parcel level.
Effect
No minimum parking requirements for multifamily or mixed-use development within 1/4 mile of transit. R-3, R-4, MU-TOD, MU-N, MU-C, MU-A parking_ratio waived in transit-proximate parcels. Minimum lot size mandates that would block qualifying multifamily projects are capped. Prior UDO requirement that each ADU have an identified parking space is effectively preempted in transit-proximate areas.
CO-SB24-174-HOUSING-NEEDS-PLANNINGapplies
Qualifying condition
city.is_in_mpo = TRUE (DRCOG) AND city.population 405,129 >= 1,000. Trigger is OR of either condition; both satisfy.
Effect
Aurora must adopt a Housing Needs Assessment and Housing Action Plan coordinated through the Colorado Department of Local Affairs (DOLA). Procedural preemption — does not directly modify zoning fields but ties state grant eligibility to plan adoption and establishes framework referenced by HB24-1152 and HB24-1313 applicability. Aurora Comprehensive Plan update cycle must integrate HNA/HAP.
CO-ADU-HOA-PREEMPTIONapplies
Qualifying condition
Trigger is attribute_present parcel.in_hoa. Aurora has a high incidence of HOA-governed subdivisions in Saddle Rock, Southshore, Tallyn's Reach, Tollgate Crossing, Cross Creek — significant HOA coverage. Predicate satisfies at parcel level anywhere an HOA exists.
Effect
HOA covenants cannot categorically prohibit ADUs that comply with state law. HOAs retain authority over aesthetic standards but cannot use CC&Rs to defeat HB24-1152's by-right ADU mandate. Aurora planning staff and title companies must flag this preemption in ADU permit reviews when HOA CC&Rs restrict.

Adopted building codes

Denver & state buildings; home rule elsewhere

IBC
Local adoption
IRC
2021
NEC
2023
IFC
Local
IECC (Residential)
Local
IECC (Commercial)
Local

Click a code label to open its state-by-state adoption atlas.

Amendment history

DateKindCitation
2025-11-03supplement effectivenote: Ord. 2025-101 latest supplement integrated into aurora.municipal.codes
2019-09-21adoptionnote: Original UDO adoption replacing the prior Chapter 122 zoning code
2019-09-21codification startnote: Chapter 146 codification begins at UDO adoption

Quirks & notes

  • Three-subarea system: Aurora's UDO divides the city into Subareas A, B, and C with different dimensional standards tables per subarea. Table 4.2-1 applies to Subareas A and B; Table 4.2-2 applies to Subarea C. Subarea C (eastern growth areas) has explicit du/ac caps (R-1 = 3, R-2 = 5 per §146-4.2.3.A) plus optional Small Residential Lot and Flexible Residential Lot development forms not available in A/B. Developer using Subarea A standards in Subarea C will get wrong answers. Highest-value quirk — easily missed by practitioners. — [c§146-4.2.2 (tables); c§146-4.2.3.A (Subarea C Small Residential Lot); c§146-4.2.3.B (Flexible Residential Lot)]
  • Buckley Space Force Base / APZ: Aurora is one of few US cities with an active military installation generating AICUZ-derived APZ zones that function as a base district, not merely an overlay. APZ district has a 1 du/ac cap for residential in APZ II; APZ I prohibits residential entirely. Federal AICUZ rules (DoD) and local APZ use restrictions combine. Substantial eastern-city impact where Buckley SFB approach/accident-potential zones extend into otherwise developable parcels. Tagged as federal_state_conflict territory where state HB24-1313 density floor meets AICUZ density cap — federal floor/ceiling governs per supremacy. — [c§146-2.6.2; c§DoD AICUZ Buckley Space Force Base; zoning/us/federal-overlays/AICUZ.json]
  • ADU parking requirement effectively removed: UDO previously required each ADU have an identified parking space. Per CO HB24-1152 (by-right ADU statewide) and HB24-1304 (parking mandate waiver near transit in MPO), any parking mandate for ADUs in Aurora's DRCOG MPO 1/4-mi transit buffer is preempted. Post-2024-05-13 practical rule: no minimum parking for ADUs in transit-proximate Aurora parcels. — [c§Colorado HB 24-1152; c§Colorado HB 24-1304]
  • MU-OA adaptive reuse height exemption: existing buildings in the MU-OA (Original Aurora) district are fully exempt from height limits as of the UDO's 2019-09-21 effective date. Only NEW habitable space triggers height standards. Creates incentive for incremental vertical additions to existing structures — legal route to very tall buildings through phased additions that avoid a single-permit height check. — [c§146-4.2 (MU-OA adaptive reuse provision); partial §146-4.2.2]
  • Cottage Development area-based density cap: Cottage Development option capped at 10 acres maximum project size with a maximum density formula of 16,000 sf of gross floor area per acre — an unusual area-based cap rather than a pure du/ac cap. Creates flexibility in unit count per acre based on unit size. — [c§146-4.2.3 (Cottage Development)]
  • HB24-1313 under active litigation (as of 2025): The Colorado TOD density preemption is being challenged. Aurora's compliance status with HB24-1313 is unclear pending judicial resolution. UDO has not been comprehensively amended to reflect the 40 du/ac floor through 2025-11 supplement. In the interim, practical advice is that projects consistent with HB24-1313 minimums (40 du/ac average) should be entitled via the state law as backup even if UDO permits less. — [c§Colorado HB 24-1313; c§2025 CO housing-preemption litigation docket]
  • Overlay codes use leading-hyphen convention (-AIO, -HPO, -CPO, -NAO): FM-1 trap for data extraction. The leading hyphen is structural — it distinguishes overlay from base district code (e.g., 'AIO' without hyphen would be ambiguous with base district nomenclature). Data systems that strip leading punctuation will collapse overlay code into something else. — [c§146-2.5.5 (-CPO, -NAO); c§146-2.6.2 (-AIO); c§146-2.6.5 (-HPO)]
  • Density basis is 'gross adjusted area' (§146-4.2.1.C): unusual definition that excludes floodplain and publicly owned land while including half of perimeter ROW. Straightforward lot-area-based density calculation is incorrect. Affects how HB24-1313 40 du/ac floor is applied — the state threshold uses standard acreage, which may create a gap between state-mandated density and Aurora-UDO-compliant density. — [c§146-4.2.1.C (gross adjusted area definition)]
  • Floodplain handled administratively rather than via a mapped overlay: No confirmed separate floodplain overlay ordinance was found distinct from FEMA-referenced standards implied in §146-4.2.3.J (Plugged Wells) and §146-5 procedures. Aurora may handle floodplain via FEMA FIRM administration rather than a distinct UDO overlay layer — a gap relative to peer cities that have explicit FPO/SFHA ordinances. — [partial §146-4.2.3.J; partial §146-5; c§FEMA FIRM Arapahoe/Adams/Douglas panels]

Formulas

Definitions

height
Grade to highest point of structure. partial §146-4.2.2 (definitions section)
lot_coverage
Building footprint / lot area. partial §146-4.2.2
far
Gross floor area / lot area. partial §146-4.2.2
du_ac
Dwelling units per acre of gross adjusted area (§146-4.2.1.C — excludes floodplain and publicly owned land; includes half of perimeter ROW). NOTE: CO HB24-1313 preempts density floors at 40 du/ac in transit-proximate MPO parcels.
setback_front
Front property line to nearest building face. partial §146-4.2.2
setback_side
Side property line to nearest building face. partial §146-4.2.2
setback_rear
Rear property line to nearest building face. partial §146-4.2.2
parking
Spaces per dwelling unit unless noted. NOTE: CO HB24-1304 waives MF/MU parking minimums within 1/4 mi transit in MPO cities.

Capacity calculations

max_footprint_sf
lot_area_sf * lot_coverage
max_gfa_sf
lot_area_sf * far
buildable_width_ft
lot_width_ft - setback_side_ft * 2
buildable_depth_ft
lot_depth_ft - setback_front_ft - setback_rear_ft
max_stories_approx
max_height_ft / 10
gross_adjusted_area_sf
lot_area_sf - floodplain_area_sf - publicly_owned_area_sf + 0.5 * perimeter_row_area_sf (§146-4.2.1.C)

Massing explorer

Interactive 3D comparison across every district. Drag to orbit, scroll to zoom, use the slider to walk districts, and toggle applicable overlays in the right-side panel.

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Parking
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District Category Height FAR Coverage Setbacks Parking Density Min lot Overlays

Sources & references

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  48. [48] n

Research status

Publication gates

primary url presentpassedcode_source set to https://aurora.municipal.codes/UDO/146 (American Legal branded, city-hosted codification of Aurora UDO Chapter 146). HTTPS; not an aggregator domain (aggregator list: zoneomics, steadily, siteplanguide, sitedesignguide, siteplancreator, propwire, zonara, unzoned).
no aggregator citedpassedScanned all citations. Only primary sources: Aurora UDO Ch. 146 (aurora.municipal.codes), Colorado General Assembly (leg.colorado.gov for HB24-1152/HB24-1313/HB24-1304/SB24-174), C.R.S. codification, FEMA NFIP (44 CFR §60.3), FAA Part 77 (14 CFR §77), DoD AICUZ Buckley Space Force Base, zoning/us/federal-overlays/*.json, zoning/us/colorado/overlays.json, U.S. Census PEP 2023 (Aurora city). Zero references to Zoneomics, Steadily, SitePlanGuide, SitePlanCreator, Propwire, Zonara, or Unzoned.
confidence tags full formpassedEvery claim carries c§ section-tag OR explicit status (partial + citation, inferred + derivation, not_found + search_performed, not_applicable + reason, preempted_by_state + preempting_law + preempted_value + preempted_effective_date). v1's bare 'c'/'i'/'p' shorthand fully replaced. Note: many district dimensional values carried forward as 'partial §146-4.2.2' because the aurora.municipal.codes site renders tables as interactive HTML that blocks direct WebFetch extraction — these values are honestly flagged rather than synthesized.
overlays have parameters trigger confidencepassedAll 5 local overlays (-AIO, -HPO, -CPO, -NAO, FLOOD) carry ordinance_ref, geographic_trigger, parameters[] (multi-element arrays), interaction_with_base, status, citation, and narrative_ref. All 5 state overlays (CO HB24-1152, HB24-1313, HB24-1304, SB24-174, ADU-HOA) surface via state_preemptions_applicable[] with qualifying_condition_checked, effect, effective_date, preempted_fields_in_this_record, status, source_ref, narrative_ref.
preempt section city specificpassedstate_preemptions_applicable[] lists 5 entries tailored to Aurora's specific status: DRCOG MPO member triggers HB24-1152, HB24-1313, HB24-1304; Census PEP 2023 population 405,129 (>1,000) triggers HB24-1152 and SB24-174; HOA presence triggers ADU-HOA preemption at parcel level. Each entry carries Aurora-specific qualifying_condition_checked computed from primary data (Census PEP 2023, DRCOG member list), not a roster lookup. v1's generic reference to 'state-preemptions/co.md' replaced with structured entries driven from state-overlays/colorado.json.

Data quality

55%completeness
Documented gaps
  • Direct extraction of §146-4.2.2 Table 4.2-1 (Subareas A/B) and Table 4.2-2 (Subarea C) — aurora.municipal.codes renders tables as interactive HTML blocking direct WebFetch
  • Per-subarea height/lot-coverage/FAR/parking values for each of R-1/R-2/R-3/R-4 in Subareas A, B, C
  • MU-OA subdistrict dimensional standards (MS, OA-R1, OA-R2, OA-C, OA-G)
  • HB24-1313 litigation resolution and Aurora UDO conformance timeline
  • Aurora MLUPA-compliant Housing Needs Assessment and Housing Action Plan adoption status per SB24-174
  • Aurora Station Area Plans for MU-TOD (R-Line stations: Peoria, Aurora Metro Center, 13th Ave, Colfax, Florida, Iliff, Nine Mile; A-Line stations: 40th/Airport/Gateway-Park, 61st/Pena)
  • Precise Buckley SFB AICUZ contour boundary within city limits for APZ I/APZ II applicability per parcel
  • Floodplain provisions — confirmation of whether a distinct FPO exists or FEMA FIRM is administered procedurally
  • Stormwater / water quality overlay (Cherry Creek watershed protection typical of eastern Denver metro; not retrieved)

Known issues

freshness:volatiledata:gaps-present

Verification

last_verified_at2026-04-19T08:45:00Z
verifier_specialistverification-pass
verifier_version1.0
verification_resultpassed
atomic_claims_checked42
atomic_claims_passed42
atomic_claims_failed0
notesAll confirmed claims carry c§ section-tag citations to UDO Chapter 146. Partial claims carry explicit partial_reason + search_performed. Inferred values removed where v1 had 'p'/'c' shorthand on unverified values; most district dimensional standards now correctly tagged 'partial' or 'not_found' rather than invented values. No aggregator citations (Zoneomics, Steadily, SitePlanGuide, SitePlanCreator, Propwire, Zonara, Unzoned — absent). Colorado 2024 preemption citations point directly to leg.colorado.gov bill pages and C.R.S. codification. Population 405,129 (Census PEP 2023 vintage) is primary-data source for HB24-1152/SB24-174 population threshold check (not roster trust). DRCOG MPO membership is the primary trigger for HB24-1313/HB24-1304/HB24-1152.

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