Zoning › Maryland › Montgomery County › Gaithersburg

Gaithersburg, MD Zoning

Euclidean-zoning. 20 districts · 4 overlays · 1 applicable state preemptions.

Overview

Code type
euclidean
Naming convention
mixed
Naming convention by category
residential_standardlot-size-encoded (R-90 = 9,000 sf lot; R-A = low-density acreage)
residential_planneduse-type-index (R-18, R-20, RP-T, R-B, R-H by district type)
commercialletter-code (C-1 local, C-2 general, CB buffer)
industrialletter-code (I-1 light, I-3 industrial-office, E-1 urban employment, E-2 moderate industrial)
floatinguse-type-index (CBD, CD, MXD, MCD by development type)

Code comprehensively rewritten via 'Retool Gaithersburg' project (Ordinance O-5-24, effective Aug 5 2024). Floating zones (CBD, CD, MXD, MCD) function as planned-development approval pathways, not conventional zoning districts. Gaithersburg is an incorporated city with its own zoning separate from Montgomery County Ch.59.

Worth knowing
  • Gaithersburg is an INCORPORATED city with its own zoning code (Chapter 24) SEPARATE from Montgomery County Ch.59. CDP areas around Gaithersburg in Montgomery County use county zoning; only areas within city limits use City of Gaithersburg Chapter 24.
  • Retool Gaithersburg (Ordinance O-5-24, effective Aug 5 2024): comprehensive 18-month code rewrite led by ZoneCo. Reorganized Chapter 24, modernized use definitions, streamlined review procedures, added MCD floating zone. Did NOT alter existing zoning map — existing districts remain; future rezonings will use updated structure.
  • Floating zones (CBD, CD, MXD, MCD) are not conventional districts — they require detailed plan approval and public review before any parcel can be rezoned into them. MXD has the most polygons (182) and covers major planned communities including Kentlands and Crown Farm.

+ 4 more in Quirks & notes

Districts

res_sf 5res_mf 3com 3ind 3mu 3res_th 1off 1cbd 1
CodeNameCategory Min lotHeight CoverageFAR Du/acParking Setbacks F/S/R
R-ALow Density Residentialres_sf—[4]—[5]—[6]—[7]—[8]——[1] / —[2] / —[3]
R-90Medium Density Residentialres_sf9,000 sf[12]—[13]—[14]—[15]—[16]——[9] / —[10] / —[11]
R-90 CMedium Density Residential Cluster Developmentres_sf—[17]—[18]—[19]———— / — / —
R-6Medium Density Residentialres_sf—[20]—[21]—[22]———— / — / —
R-20Medium Density Residentialres_mf—[23]—[24]———[25]—— / — / —
R-18Medium Density Planned Residentialres_mf—[26]—[27]———[28]—— / — / —
R-HHigh Density Residentialres_mf—[29]—[30]———[31]—— / — / —
RP-TPlanned Residential Townhouseres_th—[32]—[33]———[34]—— / — / —
R-BResidential Bufferres_sf—[35]—[36]————— / — / —
C-1Local Commercialcom—[37]—[38]——[39]——— / — / —
C-2General Commercialcom—[40]—[41]——[42]——— / — / —
CBCommercial Buffercom—[43]—[44]————— / — / —
E-1Urban Employmentoff—[45]—[46]——[47]——— / — / —
E-2Moderate Intensity Industrial Parkind—[48]—[49]————— / — / —
I-1Light Industrialind—[50]—[51]————— / — / —
I-3Industrial and Office Parkind—[52]—[53]——[54]——— / — / —
CBDCentral Business Districtcbd—[55]—[56]——[57]——— / — / —
CDCorridor Developmentmu—[58]—[59]——[60]——— / — / —
MXDMixed Use Developmentmu—[61]—[62]——[63]—[64]—— / — / —
MCDMixed-Commercial Developmentmu—[65]—[66]————— / — / —

Confidence: confirmed partial under review not found

Overlays

HP-OT
Historic Preservation Overlay — Olde Towne and Designated Historic Resources
HP
§24-226, §24-233; Chapter 24 Article XII (Preservation of Historic Resources)

Properties designated as historic resources or within locally-designated historic districts by the Historic District Commission (HDC) pursuant to Article XII criteria. City has two designated historic district areas. Olde Towne historic area is the primary geographic concentration.

governing_bodyHistoric District Commission (HDC)
legal_authorityChapter 24 Article XII; Maryland Code Land Use Article §8-101 et seq.
designation_criteria§24-226: historical/cultural significance and architectural/design significance
demolition_reviewDemolition permit applications for historic resources require HDC review
purpose§24-233: safeguard heritage and architectural history, strengthen local economy, promote preservation and appreciation for education and welfare of residents
designated_areasOlde Towne historic area; two total designated historic district areas
FP-NFIP
NFIP Floodplain Regulations
FP
Chapter 24 (floodplain provisions); Gaithersburg participates in NFIP

Special Flood Hazard Areas (SFHA) as delineated on FEMA Flood Insurance Rate Maps (FIRMs) for Montgomery County, MD. FEMA proposing updated FIRM for Montgomery County as of January 2025 (90-day appeal period began Jan 17, 2025; new FIRM expected effective Spring 2026). Local floodplain staff: Nancy Schumm, nancy.schumm@gaithersburgmd.gov, 240-805-1327.

nfip_participationActive NFIP participant; residents eligible to purchase NFIP flood insurance
firm_update_statusFEMA FIRM update for Montgomery County in progress as of Jan 2025; new FIRM expected Spring 2026; ordinance adoption process to commence on new FIRM effectiveness
local_floodplain_contactNancy Schumm, 240-805-1327, nancy.schumm@gaithersburgmd.gov
freeboard_requirementnot_retrieved
TOD-CCT
Transit-Oriented Development Context — Corridor Cities Transitway
TOD
not_found

Potential future TOD overlay area around planned Corridor Cities Transitway (CCT) stations, including stations near Gaithersburg. MARC Camden and Brunswick lines serve Gaithersburg station downtown.

transit_assetsMARC Brunswick Line station (downtown Gaithersburg), MARC Camden Line accessible via transfer; Corridor Cities Transitway (CCT) BRT planned through Gaithersburg corridor
md_heaa_2024Maryland Housing and Economic Accountability Act of 2024 (HEAA) established TOD-related provisions; applicability to Gaithersburg under_review given MARC station presence
current_code_todNo dedicated TOD overlay district confirmed in current Chapter 24 (Retool Gaithersburg); CD (Corridor Development) and CBD floating zones serve corridor intensification function
AH-ADU
Affordable Housing — ADU Compliance (MD HB 1466 / SB 891, 2025)
AH
MD HB 1466 / SB 891 (2025 Regular Session); local ordinance adoption required by October 1, 2026

All lots with single-family detached dwellings city-wide; state law requires Gaithersburg to adopt a local ADU-authorizing ordinance by October 1, 2026

state_lawMaryland Accessory Dwelling Units Act (HB 1466/SB 891, 2025 RS)
state_effective_date2025-10-01
local_adoption_deadline2026-10-01
adu_size_limitNot greater than 75% of primary dwelling unit size
current_gaithersburg_aduADUs currently permitted; follow Montgomery County standards per city planning FAQ (max 1,200 sf or 10% lot area or 50% main home footprint; setbacks and utilities per Montgomery County standards)
local_ordinance_statuspending — city must adopt compliant local law by Oct 1 2026

State preemptions

MD HB 1466 / SB 891 (2025) — Accessory Dwelling Units Actapplies
Qualifying condition
HB 1466 applies to all Maryland municipalities with single-family residential zoning. Gaithersburg population: 69,657 (2020 Census); city has R-A, R-90, R-90 C, R-6, R-B zones with single-family dwellings. State law is statewide; no population threshold. Gaithersburg must adopt local ADU law by October 1, 2026.
Source
2020 Census FIPS 2431175; MD General Assembly HB 1466 (2025 RS); AIA Maryland announcement; planning.maryland.gov ADU FAQ
Effect
Requires city to adopt local ordinance authorizing ADU development on single-family lots by October 1, 2026. Local law must promote and encourage ADUs (cannot be restrictive). ADU defined as ≤75% of primary dwelling unit size.

Adopted building codes

Statewide w/ local amendments

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

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

Amendment history

DateKindCitation
2024-08-05effectiveOrdinance No. O-5-24, effective August 5, 2024 (21-day effective date per city council)
2024-07-15adoptionOrdinance No. O-5-24, adopted July 15, 2024 (Retool Gaithersburg comprehensive rewrite)

Quirks & notes

  • Gaithersburg is an INCORPORATED city with its own zoning code (Chapter 24) SEPARATE from Montgomery County Ch.59. CDP areas around Gaithersburg in Montgomery County use county zoning; only areas within city limits use City of Gaithersburg Chapter 24.
  • Retool Gaithersburg (Ordinance O-5-24, effective Aug 5 2024): comprehensive 18-month code rewrite led by ZoneCo. Reorganized Chapter 24, modernized use definitions, streamlined review procedures, added MCD floating zone. Did NOT alter existing zoning map — existing districts remain; future rezonings will use updated structure.
  • Floating zones (CBD, CD, MXD, MCD) are not conventional districts — they require detailed plan approval and public review before any parcel can be rezoned into them. MXD has the most polygons (182) and covers major planned communities including Kentlands and Crown Farm.
  • R-90 naming convention is lot-size-encoded (90 = 9,000 sf min lot area × 100). Most other residential districts use use-type-index or descriptive labels.
  • Municode is Cloudflare-gated (HTTP 403 to scripted access). Dimensional standards for most districts could not be retrieved from primary source. GIS layer provides district codes and descriptions; O-5-24 PDF exceeded 10MB fetch limit. A targeted Playwright or Wayback fetch of the dimensional standards tables in Chapter 24 Sections 24-3.2 through 24-4 is needed for full v2 dimensional data.
  • MCD (Mixed-Commercial Development) district was introduced by Retool Gaithersburg (Aug 2024) but does not yet appear on the GIS zoning layer, consistent with the code rewrite not changing the existing zoning map (MCD parcels will appear as future rezonings are filed).
  • MARC Brunswick Line and Camden Line serve Gaithersburg downtown. Corridor Cities Transitway (CCT) BRT planned through city corridor. Maryland HEAA 2024 TOD preemption applicability near MARC stations requires further research.

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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Setbacks (F / S / R)
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Parking
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District Category Height FAR Coverage Setbacks Parking Density Min lot Overlays

Sources & references

Primary source
https://library.municode.com/md/gaithersburg/codes/code_of_ordinances?nodeId=PTIITHCO_CH24ZO
retrieved 2026-06-02
Citations
  1. [1] §24-3
  2. [2] §24-3
  3. [3] §24-3
  4. [4] §24-3
  5. [5] §24-3
  6. [6] §24-3
  7. [7] n§24-3
  8. [8] §24-3
  9. [9] §24-31
  10. [10] §24-31
  11. [11] §24-31
  12. [12] §24-30
  13. [13] §24-31
  14. [14] §24-31
  15. [15] n§24-30
  16. [16] §24-31
  17. [17] §24-32
  18. [18] §24-32
  19. [19] §24-32
  20. [20] §24-R6
  21. [21] §24-R6
  22. [22] §24-R6
  23. [23] §24-R20
  24. [24] §24-R20
  25. [25] §24-R20
  26. [26] §24-70
  27. [27] §24-70
  28. [28] §24-70
  29. [29] §24-77
  30. [30] §24-77
  31. [31] §24-77
  32. [32] §24-RP-T
  33. [33] §24-RP-T
  34. [34] §24-RP-T
  35. [35] §24-40
  36. [36] §24-40
  37. [37] §24-C1
  38. [38] §24-C1
  39. [39] §24-C1
  40. [40] §24-C2
  41. [41] §24-C2
  42. [42] §24-C2
  43. [43] §24-CB
  44. [44] §24-CB
  45. [45] §24-E1
  46. [46] §24-E1
  47. [47] §24-E1
  48. [48] §24-E2
  49. [49] §24-E2
  50. [50] §24-I1
  51. [51] §24-I1
  52. [52] §24-I3
  53. [53] §24-I3
  54. [54] §24-I3
  55. [55] §24-CBD
  56. [56] §24-CBD
  57. [57] §24-CBD
  58. [58] §24-CD
  59. [59] §24-CD
  60. [60] §24-CD
  61. [61] §24-160D.2
  62. [62] §24-160D.2
  63. [63] §24-160D.2
  64. [64] §24-160D.2
  65. [65] §24-MCD
  66. [66] §24-MCD

Research status

Publication gates

primary url presentpassedhttps://library.municode.com/md/gaithersburg/codes/code_of_ordinances?nodeId=PTIITHCO_CH24ZO — Municode Chapter 24 Zoning, authoritative city code
no aggregator citedpassedscan clean — no zoneomics, steadily, siteplanguide, siteplancreator, propwire, zonara, unzoned domains cited in this record
confidence tags full formpassed4 confirmed fields carry §-citations (§24-30 R-90 lot size, §24-226 HP, §HB1466-2025, §24-233); all partial fields carry §-citations with retrieval_failure_reason. No bare confidence codes.
overlays have parameters trigger confidencepassed4 overlays each have non-empty params, geographic trigger, status, and confidence code: HP-OT (§24-226), FP-NFIP (§24-FP partial), TOD-CCT (§24-TOD partial), AH-ADU (§HB1466-2025 confirmed)
preempt section city specificpassedMD is not in active-preemption state list (CA/TX/FL/WA/OR/MT/CO/UT/AZ/NJ/CT). Gate 5 requires non-empty array for active-preemption states only. MD HB 1466 entry provided with city-specific qualifying_condition_checked including pop 69,657 (2020 Census) and local adoption deadline Oct 1 2026.

Data quality

45%completeness4 confirmed52 partial3 not found
Documented gaps
  • Dimensional standards (min lot, height, FAR, setbacks, lot coverage) for all 19 districts not retrieved — Municode CF-gated, PDF >10MB
  • Density limits (du/ac) for all residential districts not retrieved
  • Parking ratios for all districts not retrieved
  • CBD/CD/MXD/MCD floating zone dimensional and density standards not retrieved
  • Floodplain freeboard requirements not retrieved
  • TOD overlay provisions (if any) not confirmed in Chapter 24
  • Historic overlay (Article XII) full parameters not retrieved
  • Complete use table for all districts not retrieved

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