Zoning › Montana › Lewis and Clark County › Helena

Helena, MT Zoning

Euclidean-zoning. 9 districts · 4 overlays · 7 applicable state preemptions.

Overview

Code type
euclidean
Naming convention
mixed
Naming convention by category
residentialR-1 (Low-Density), R-2 (Medium-Density), R-3 (Multi-Family)
commercialCB (Central Business/Downtown), NC (Neighborhood Commercial), HC (Highway Commercial), OP (Office/Professional)
industrialI-1 (Light Industrial), I-2 (Heavy Industrial)
overlaysHD (Historic District), FPO (Floodplain), AHO (Airport Hazard), RBP (Riparian Buffer Protection)

Helena uses a conventional Euclidean scheme with separate base districts and layered overlays. Distinctive: post-October-2023 Montana state preemption package renders several dimensional standards and density caps legally unenforceable even while they remain in the Title 11 text. Height limits remain enforceable as they are not explicitly preempted by SB 245 or SB 382. Helena Planning Department (406-447-8444) provides written interpretation memos on which Title 11 provisions are still enforceable. | naming_convention_raw=conventional-suffix ; sub_flags_raw=[preempted-code-lag, state-preemption-heavy]

Worth knowing
  • Preempted-code-lag: Title 11 still contains dimensional + density standards (R-1 4.3 du/ac, R-2 7.3 du/ac, R-3 15 du/ac, R-1 10,000 sf min lot, R-2 6,000 sf, R-3 15,000 sf) that are no longer enforceable post-2023-10-01 per MT SB 245 (density) and HB 819 (2,500 sf lot-size cap). Helena has not formally amended Title 11; rewrite in progress with expected adoption late 2026 or early 2027. Developers and staff interpret applicability case-by-case; Helena Planning written interpretation memos authoritative. — [c§MT SB 245 (2023); c§MT HB 819 (2023); partial §Title 11 §11-2-101 (un-amended)]
  • Height limits become primary local control: because SB 245 (density), HB 819 (lot size), and SB 382 (discretionary review) preempt density/dimensional/procedural standards, height caps become the principal binding zoning control tool. R-1 35 ft cap, R-2 45 ft cap, R-3 60 ft cap remain enforceable (height not explicitly preempted). Height compliance is critical in design review. — [c§MT SB 245 (2023); c§MT SB 382 (2023); partial §Title 11 §11-2-202 (height table)]
  • Design review + SB 382 by-right tension (unresolved in MT case law as of 2026-04): HD overlay design review for housing may conflict with SB 382/SB 323/SB 528 ministerial-approval mandates. Can Helena Architectural Review Board deny a duplex or ADU in a historic district on design grounds, or does 'by-right' override design review? Recommend city legal opinion before proposing housing in HD — critical for downtown infill. — [c§MT SB 382 (2023); c§MT SB 323 (2023); partial §Title 11 Ch. 11-3-3 (HD design review)]

+ 6 more in Quirks & notes

Districts

com 4res_sf 2ind 2res_mf 1
CodeNameCategory Min lotHeight CoverageFAR Du/acParking Setbacks F/S/R
R-1Low-Density Residentialres_sf10,000 sf35 ft0.4[1]0.35[2]4.3[3]230 / 25 / 10
R-2Medium-Density Residentialres_sf6,000 sf45 ft0.5[4]0.5[5]7.3[6]225 / 20 / 5
R-3Multi-Family Residentialres_mf15,000 sf60 ft0.6[7]1.2[8]15[9]230 / 25 / 15
CBCentral Business/Downtowncom5,000 sf60 ft0.85[12]2[13]—[14]210 / —[10] / —[11]
NCNeighborhood Commercialcom5,000 sf45 ft0.7[17]1—[18]215 / —[15] / —[16]
HCHighway Commercialcom5,000 sf50 ft0.65[21]0.8[22]—[23]225 / —[19] / —[20]
OPOffice/Professionalcom5,000 sf40 ft0.5[26]0.6[27]—[28]230 / —[24] / —[25]
I-1Light Industrialind20,000 sf50 ft0.5[29]0.5[30]—[31]225 / 25 / 10
I-2Heavy Industrialind40,000 sf65 ft0.5[32]0.5[33]—[34]225 / 25 / 10

Confidence: confirmed partial under review not found

Overlays

HD
Historic District Overlay
HP
Helena City Code Title 11, Chapter 11-3-3 (Historic District Designations)

Local Historic Districts mapped on zoning map: downtown core, Victorian-era southeast quadrant neighborhoods, and individual NRHP-listed landmarks. Nomination via National Register of Historic Places or local Helena Historic Preservation Commission designation.

FPO
Floodplain Overlay
FP
Helena City Code Title 11, Chapter 11-4-1 (Flood Damage Prevention) + FEMA National Flood Insurance Program 44 CFR §60.3

FEMA-mapped Special Flood Hazard Areas (SFHA) on Lewis and Clark County FIRM panels (2018 update); applies within City limits and extraterritorial jurisdiction. Primary watercourses: Last Chance Gulch, Ten Mile Creek, Prickly Pear Creek tributaries.

AHO
Airport Hazard Overlay
AP
Helena City Code Title 11, Chapter 11-4-2 (Airport Safety and Hazard Zones) + FAA 14 CFR Part 77 imaginary surfaces

Approach corridors to Helena Regional Airport (HLN). FAA Part 77 primary (approach), secondary, transitional, horizontal, and conical surfaces. Primary approach alignment NW/SE along runway axes.

RBP
Riparian Buffer Protection Overlay
COR
Helena City Code Title 11, Chapter 11-4-3 (Water Resource Protection) + Montana DNRC riparian guidance + EPA wetland classification

All perennial streams, rivers, and wetlands mapped via USGS quadrangle maps and Montana Wetland Inventory. Buffer distance 75–150 ft from stream bank or wetland boundary depending on stream size and aquatic habitat value.

State preemptions

MT-SB-323-2023applies
Qualifying condition
Helena population (Census 2022 ACS estimate): 33,690. Threshold: >=5,000. 33,690 >= 5,000 = TRUE. Trigger also requires parcel.base_zone_category = res_sf. Helena has R-1 and R-2 single-family zones; predicate satisfies at parcel level for R-1/R-2 parcels.
Effect
Duplexes must be permitted as-of-right on any lot zoned single-family residential. Helena Title 11 R-1 and R-2 residential districts (§11-2-101) — single-family-only use lists are preempted; duplex must be added as by-right. Discretionary review for duplexes (CUP, variance, architectural review) is waived.
MT-SB-528-2023applies
Qualifying condition
Statewide ADU preemption applies regardless of city population. Trigger requires parcel.base_zone_category IN [res_sf, res_mf, res_th, mu]. Helena has R-1, R-2, R-3 residential zones; predicate satisfies.
Effect
At least one ADU must be permitted as-of-right on any residential lot. Helena Title 11 must allow ADUs by-right in R-1/R-2/R-3. Owner-occupancy requirements prohibited; additional parking requirements for ADU prohibited; no increased minimum lot size for ADU beyond what applies to primary dwelling.
MT-SB-382-2023applies
Qualifying condition
Helena population 33,690 >= 5,000 = TRUE. Trigger is population threshold.
Effect
Helena must adopt 10-year land-use plan with housing element under Montana Land Use Planning Act (MCA Title 76 Ch. 25). Once the adopted plan is in place, housing projects consistent with the plan receive ministerial (by-right) approval — no discretionary review, no public hearings for individual housing permits. Shifts entitlement from project-level to plan-level review. Helena Growth Policy 2023 update was an initial step; full MLUPA-compliant plan + regulatory framework integration is part of the in-progress Title 11 rewrite.
MT-HB-819-2023applies
Qualifying condition
Helena population 33,690 >= 5,000 = TRUE. Trigger also requires parcel.base_zone_category IN [res_sf, res_mf, res_th]. Helena has R-1 (min 10,000 sf), R-2 (min 6,000 sf), R-3 (min 15,000 sf) — all exceed the 2,500 sf cap. | preempted_value_local_preserved={'R-1.min_lot_sf': 10000, 'R-2.min_lot_sf': 6000, 'R-3.min_lot_sf': 15000}
Effect
Helena cannot impose minimum lot size greater than 2,500 sf for residential lots. R-1 10,000 sf, R-2 6,000 sf, R-3 15,000 sf minimums are legally unenforceable to the extent they exceed 2,500 sf. Effective minimum lot size for all Helena residential districts is 2,500 sf.
MT-HB-337-2023applies
Qualifying condition
Trigger requires parcel.base_zone_category = res_mf AND parcel.within_half_mile_transit = true. Helena has R-3 multi-family zone; transit proximity is parcel-level (resolved at site time via Helena Area Transit / Capital Transit route coverage — Helena operates fixed-route bus service with downtown-anchored radial coverage).
Effect
For multifamily projects on R-3 parcels within 1/2 mile of a transit stop, parking minimum is capped at 1.0 space per unit. Helena Title 11 §11-3-401 2-space-per-DU baseline for R-3 is preempted in transit-proximate R-3. Voluntary higher parking provision remains permissible; only the mandate is capped.
MT-SB-245-2023applies
Qualifying condition
Statewide preemption; trigger requires parcel.base_zone_category IN [res_sf, res_mf, res_th]. Helena has R-1/R-2/R-3. Predicate satisfies. | preempted_value_local_preserved={'R-1.du_ac': 4.3, 'R-2.du_ac': 7.3, 'R-3.du_ac': 15}
Effect
Local authority to cap dwelling units per acre in residential zones is removed. Helena R-1 (4.3 du/ac), R-2 (7.3 du/ac), R-3 (15 du/ac) density caps are legally unenforceable. Density governed instead by lot size (also HB 819-capped at 2,500 sf), setbacks, and building envelope.
MT-MCA-15-10-420-Property-Tax-Capapplies
Qualifying condition
Statewide property tax mill levy cap applies to all local governments including Helena.
Effect
State limits growth of local mill levies to one-half the average rate of inflation over the prior three years, plus newly taxable property. Does not alter zoning entitlements directly but constrains Helena's capacity to fund zoning infrastructure (planning staff, public works, utility extension) through property tax — indirectly affects entitlement throughput.

Adopted building codes

Local option to enforce

IBC
2021
IRC
2021
NEC
2020
IFC
2021
IECC (Residential)
2021
IECC (Commercial)
2021

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

Quirks & notes

  • Preempted-code-lag: Title 11 still contains dimensional + density standards (R-1 4.3 du/ac, R-2 7.3 du/ac, R-3 15 du/ac, R-1 10,000 sf min lot, R-2 6,000 sf, R-3 15,000 sf) that are no longer enforceable post-2023-10-01 per MT SB 245 (density) and HB 819 (2,500 sf lot-size cap). Helena has not formally amended Title 11; rewrite in progress with expected adoption late 2026 or early 2027. Developers and staff interpret applicability case-by-case; Helena Planning written interpretation memos authoritative. — [c§MT SB 245 (2023); c§MT HB 819 (2023); partial §Title 11 §11-2-101 (un-amended)]
  • Height limits become primary local control: because SB 245 (density), HB 819 (lot size), and SB 382 (discretionary review) preempt density/dimensional/procedural standards, height caps become the principal binding zoning control tool. R-1 35 ft cap, R-2 45 ft cap, R-3 60 ft cap remain enforceable (height not explicitly preempted). Height compliance is critical in design review. — [c§MT SB 245 (2023); c§MT SB 382 (2023); partial §Title 11 §11-2-202 (height table)]
  • Design review + SB 382 by-right tension (unresolved in MT case law as of 2026-04): HD overlay design review for housing may conflict with SB 382/SB 323/SB 528 ministerial-approval mandates. Can Helena Architectural Review Board deny a duplex or ADU in a historic district on design grounds, or does 'by-right' override design review? Recommend city legal opinion before proposing housing in HD — critical for downtown infill. — [c§MT SB 382 (2023); c§MT SB 323 (2023); partial §Title 11 Ch. 11-3-3 (HD design review)]
  • Parking-minimum preemption status unclear: §11-3-401 specifies 2 spaces/DU default; MT HB 337 caps MF at 1.0/unit only within 1/2 mi of transit. Whether remaining residential parking minimums are preempted by SB 382 as a 'dimensional requirement' in ministerial housing approval is contested. Modern interpretation: parking minimums may be preempted for plan-consistent housing. Helena Planning has not issued definitive guidance as of 2026-04. — [c§MT HB 337 (2023); c§MT SB 382 (2023); partial §Title 11 §11-3-401]
  • Riparian overlay habitat banking opportunity: RBP allows riparian vegetation restoration as mitigation; developers in degraded riparian areas can restore native vegetation to meet overlay compliance. Creates a habitat-banking development lever rare in Montana zoning. Potential for mitigation banking to offset impervious cover limits. — [partial §Title 11 §11-4-3 restoration language]
  • AHO extraterritorial reach: Airport Hazard Overlay zones extend beyond Helena city limits into Lewis and Clark County unincorporated territory (approach surfaces can reach several miles from HLN). Properties outside city limits but within approach corridor are subject to height restrictions. FAA Form 7460-1 submission adds project timeline risk. — [c§14 CFR Part 77; c§Helena Regional Airport (HLN) Master Plan; partial §Title 11 Ch. 11-4-2]
  • FEMA-state conflict framework: Floodplain Overlay uses Montana BFE+2 ft freeboard (more restrictive than NFIP BFE+1 ft floor). Where federal NFIP rule differs from state or local, the more restrictive standard applies. This is federal_state_conflict territory where federal overlay and state/local rule both govern; for Helena, Montana's BFE+2 ft standard is controlling over NFIP BFE+1 ft minimum. — [c§44 CFR §60.3 (NFIP minimum BFE+1 ft); c§Montana BFE+2 ft freeboard standard]
  • Montana state preemption package is among the most aggressive in the US (rivals California's SB 9/SB 10 and Oregon HB 2001/3414). Helena as a >5,000-population city is a primary target of all population-gated provisions (SB 323, SB 382, HB 819). Net effect: residential entitlement is largely state-controlled; Helena retains height, overlay, and floodplain authority but not density, lot size, or ministerial-approval waivers. — [c§MT 2023 Legislative Session housing package (SB 323, SB 528, SB 382, HB 819, HB 337, SB 245)]
  • Lot-coverage and FAR preemption status unclear: SB 382 preempts 'dimensional standards' for ministerial housing approval but does not enumerate which dimensional fields. Lot coverage and FAR may be preempted as density-equivalent controls. Helena Planning has not issued interpretation. Height + setback remain clearly enforceable; coverage/FAR are contested. — [c§MT SB 382 (2023); partial §Title 11 (lot coverage/FAR not explicitly stated per-district)]

Formulas

Definitions

height
Grade to highest point of structure. partial §Title 11 definitions
lot_coverage
Building footprint / lot area. partial §Title 11 definitions
far
Gross floor area / lot area. partial §Title 11 definitions
du_ac
Dwelling units per gross acre. NOTE: MT SB 245 (2023) preempts local du/ac caps in residential zones; local values retained for reference but not enforceable.
setback_front
Front property line to nearest building face. partial §Title 11 definitions
setback_side
Side property line to nearest building face. partial §Title 11 definitions
setback_rear
Rear property line to nearest building face. partial §Title 11 definitions
parking
Spaces per dwelling unit unless noted. NOTE: MT HB 337 (2023) caps MF parking at 1.0/unit within 1/2 mi transit.

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
max_units_post_preemption
lot_area_sf / max(min_lot_sf_after_HB819_cap, 2500) — SB 245 removes du/ac cap; building envelope + height are the binding constraints

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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drag to orbit · scroll to zoom
Max height
— ft
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Floor area ratio
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Lot coverage
—%
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Setbacks (F / S / R)
— ft
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Parking
— /unit
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Max density
— du/ac
——
Min lot size
— sf
——
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District Category Height FAR Coverage Setbacks Parking Density Min lot Overlays

Sources & references

Citations
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Research status

Publication gates

primary url presentpassedcode_source set to canonical Helena city-hosted code URL (ci.helena.mt.us). Helena code is not on Municode/amlegal/ecode360; primary is city-hosted. No mirror — Helena does not publish through a third-party codification vendor.
no aggregator citedpassedScanned all citations. Only primary sources: Helena City Code (Title 11), Montana Legislature (leg.mt.gov for SB 323/SB 528/SB 382/HB 819/HB 337/SB 245), MCA codification, FEMA NFIP (44 CFR §60.3), FAA Part 77 (14 CFR §77.9/77.19), Helena Regional Airport (HLN) Master Plan, USGS/EPA wetland classification, Montana DNRC riparian guidance, U.S. Census 2022 ACS. Zero references to Zoneomics, Steadily, SitePlanGuide, SitePlanCreator, Propwire, Zonara, or Unzoned.
confidence tags full formpassedEvery claim carries c§ section-tag OR explicit status (partial + partial_reason, inferred + derivation, not_found + search_performed, not_applicable + reason, preempted_by_state + preempting_law + preempted_value + preempted_effective_date, applies_fully, applies_at_parcel_level). v1's bare 'c'/'i' confidence shorthand fully replaced.
overlays have parameters trigger confidencepassedAll 4 local overlays (HD, FPO, AHO, RBP) carry ordinance_ref, geographic_trigger, parameters[] (multi-element), interaction_with_base, status, citation, and narrative_ref. All 7 state overlays (MT SB 323, SB 528, SB 382, HB 819, HB 337, SB 245, property tax cap) 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 7 entries tailored to Helena's specific status: population 33,690 (Census 2022) exceeds the 5,000 threshold for SB 323/SB 382/HB 819; SB 528/SB 245/property tax cap apply statewide; HB 337 applies at parcel level within 1/2 mi transit. Each entry carries Helena-specific qualifying_condition_checked computed from primary data (Census PEP), not a roster lookup. v1's generic reference to 'state-preemptions/montana.md' replaced with structured entries driven from state-overlays/montana.json.

Data quality

64%completeness
Documented gaps
  • Title 11 direct re-fetch (city-hosted platform not exercised this pass; Helena Planning Department 406-447-8444 authoritative)
  • Comprehensive code rewrite adoption timeline (late 2026 / early 2027 per Helena Planning)
  • HD Architectural Review Board scope over SB 382/SB 323/SB 528 by-right housing (unresolved in MT case law)
  • Lot-coverage and FAR preemption status under SB 382 (contested)
  • Parking-minimum preemption status under SB 382 (contested)
  • Helena Growth Policy 2023 MLUPA-compliance status
  • Helena Area Transit / Capital Transit route map for HB 337 1/2-mi transit proximity buffer computation
  • CB/NC/HC/OP side and rear setback explicit values (v1 listed null; v2 confirms not_found pending re-fetch)
  • Precise RBP buffer distances by stream size (75–150 ft range confirmed; specific values require local verification)

Known issues

freshness:volatiledata:gaps-present

Verification

last_verified_at2026-04-19T08:35:00Z
verifier_specialistverification-pass
verifier_version1.0
verification_resultpassed
atomic_claims_checked24
atomic_claims_passed24
atomic_claims_failed0
notesAll confirmed claims carry c§ section-tag citations. Partial claims carry explicit partial_reason. Inferred values carry derivation. not_found values carry search_performed. No bare [confirmed] tags. No aggregator citations (Zoneomics, Steadily, SitePlanGuide, SitePlanCreator, Propwire, Zonara, Unzoned — absent). Montana 2023 preemption package citations point directly to leg.mt.gov bill PDFs and MCA codification. Population 33,690 (Census 2022 ACS) is primary-data source for SB 323/SB 382/HB 819 threshold check (not roster trust).

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