Overview
Code type
euclidean
Naming convention
conventional-suffix-mixed-with-subarea
| residential | R-R (Rural), R-1 (Low-Density), R-2 (Medium-Density), R-3 (High-Density), R-4 (Very High-Density) |
|---|---|
| mixed_use | MU-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) |
| industrial | I-1 (Business/Tech), I-2 (Industrial) |
| special | APZ (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.
Districts
mu 7res_sf 3special 3res_mf 2industrial 2
| Code | Name | Category | Min lot | Height | Coverage | FAR | Du/ac | Parking | Setbacks F/S/R |
|---|---|---|---|---|---|---|---|---|---|
| R-R | Rural | res_sf | — | 35 ft | — | — | — | 2 | 25 / 25 / 10 |
| R-1 | Low-Density Residential | res_sf | 5,000 sf | 35 ft | — | — | 3 | 2 | 20 / 5 / 20 |
| R-2 | Medium-Density Residential | res_sf | 5,000 sf | 35 ft | — | — | 5 | 2 | 25 / 25 / 10 |
| R-3 | High-Density Residential | res_mf | 5,000 sf | 35 ft | — | — | — | — | 25 / 25 / 10 |
| R-4 | Very High-Density Residential | res_mf | 5,000 sf | — | — | — | — | — | 25 / 25 / 10 |
| MU-N | Neighborhood Mixed-Use | mu | 5,000 sf | — | — | — | — | — | 25 / 25 / 10 |
| MU-C | Community Mixed-Use | mu | 5,000 sf | — | — | — | — | — | 25 / 25 / 10 |
| MU-OI | Office-Industrial Mixed-Use | mu | 5,000 sf | — | — | — | — | — | 25 / 25 / 10 |
| MU-OA | Original Aurora Mixed-Use | mu | 5,000 sf | — | — | — | — | — | — / — / — |
| MU-TOD | Transit-Oriented Development | mu | 5,000 sf | — | — | — | — | — | 25 / 25 / 10 |
| MU-A | Aurora Mixed-Use | mu | 5,000 sf | — | — | — | — | — | 25 / 25 / 10 |
| MU-FB | Fitzsimons Boundary Mixed-Use | mu | 5,000 sf | — | — | — | — | — | 25 / 25 / 10 |
| APZ | Airport Protection Zone | special | — | — | — | — | 1 | — | — / — / — |
| AD | Airport District | special | — | — | — | — | — | — | 25 / 25 / 10 |
| I-1 | Business/Tech District | industrial | 5,000 sf | — | — | — | — | — | 25 / 25 / 10 |
| I-2 | Industrial District | industrial | 5,000 sf | — | — | — | — | — | 25 / 25 / 10 |
| POS | Parks and Open Space | special | — | — | — | — | — | — | 25 / 25 / 10 |
Confidence: confirmed partial under review not found
Overlays
-AIO
Airport Influence Overlay
AP-HPO
Historic Protection Overlay
HP-CPO
Conservation Parks Overlay
COR-NAO
Natural Areas Overlay
CORFLOOD
Floodplain Provisions
FPState 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.
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.
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
Click a code label to open its state-by-state adoption atlas.
Amendment history
| Date | Kind | Citation |
|---|---|---|
| adoption | ||
| supplement effective | ||
| codification start |
Quirks & notes
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.
Sort by
Max height
— ft
——
Floor area ratio
—
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Lot coverage
—%
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Setbacks (F / S / R)
— ft
——
Parking
— /unit
——
Max density
— du/ac
——
Min lot size
— sf
——
Copy zoning profile
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| District | Category | Height | FAR | Coverage | Setbacks | Parking | Density | Min lot | Overlays |
|---|
Research status
Publication gates
| primary url present | passed | code_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 cited | passed | Scanned 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 form | passed | Every 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 confidence | passed | All 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 specific | passed | state_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_at | 2026-04-19T08:45:00Z |
|---|---|
| verifier_specialist | verification-pass |
| verifier_version | 1.0 |
| verification_result | passed |
| atomic_claims_checked | 42 |
| atomic_claims_passed | 42 |
| atomic_claims_failed | 0 |
| notes | All 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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