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Commercial Building Permit (New Construction, Addition, Alteration, Repair) in Darby, Montana

Required for new construction, additions, alterations, and repairs to commercial structures within the Town of Darby. Darby's Montana DLI certification for Building (B), Plumbing (P), Mechanical (M), Electrical (E), and Swimming Pool (SP) carries no residential-only qualifier, so the Town issues and inspects commercial building permits itself rather than routing them to the state. Darby publishes no separate commercial application, fee table, or plan-review charge, however: the same Building Permit Application and the same valuation-based Building Permit Fee Schedule used for residential work govern a commercial project as well.

Verified 2026-08-26 · Source

When you need this permit

  • Building permit required for new construction, additions, alterations, repairs, and other structural work on a commercial building in Darby
  • Filed on the Town's general Building Permit Application — the form has a single 'Describe nature of the project and the building use or occupancy' field and a 'Type of Work' checklist (New/Addition/Alteration/Repair/Mobile Home/Re-Roof/Demolish/Other) with no separate residential/commercial track
  • Provide a plot plan showing building location and distances from each side of the lot, indicating alleys or streets
  • Provide 2 sets of plans drawn to scale, including foundation, floor and roof framing, floor plans, and exterior elevations (one set may be submitted digitally)
  • All work must conform to the most current adopted building codes (IBC, IRC, IEBC, ISPSC, IECC, NEC, IMC, IFGC, UPC) and Montana Administrative Rules (A.R.M.), plus applicable local codes
  • Design criteria compliance: 46.0 psf ground snow load, 112 mph wind speed, Seismic Design Category C, severe weathering, 36-inch frost line depth, required ice shield underlayment
  • Setback compliance: occupied buildings 25 ft front/rear, 5 ft sides (15 ft corner lot); accessory buildings 25 ft front, 7.5 ft rear, same side setbacks as occupied buildings

Required documents

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Fee schedule

Building Permit Fee (applies to any structure, commercial or residential) — valuation $1.00 to $500.00Town of Darby Building Permit Fee Schedule (Res. 649, updated 4/13/2021) — a single valuation table with no separate commercial tier or multiplier
$29.38
Building Permit Fee — valuation $501.00 to $2,000.00Town of Darby Building Permit Fee Schedule
$29.38 for the first $500.00, plus $3.81 for each additional $100.00 or fraction thereof
Building Permit Fee — valuation $2,001.00 to $25,000.00Town of Darby Building Permit Fee Schedule
$86.56 for the first $2,000.00, plus $17.50 for each additional $1,000.00 or fraction thereof
Building Permit Fee — valuation $25,001.00 to $50,000.00Town of Darby Building Permit Fee Schedule
$489.06 for the first $25,000.00, plus $12.63 for each additional $1,000.00 or fraction thereof
Building Permit Fee — valuation $50,001.00 to $100,000.00Town of Darby Building Permit Fee Schedule
$804.69 for the first $50,000.00, plus $8.75 for each additional $1,000.00 or fraction thereof
Building Permit Fee — valuation $100,001.00 to $500,000.00Town of Darby Building Permit Fee Schedule
$1,242.19 for the first $100,000.00, plus $7.00 for each additional $1,000.00 or fraction thereof
Building Permit Fee — valuation $500,001.00 to $1,000,000.00Town of Darby Building Permit Fee Schedule
$4,042.19 for the first $500,000.00, plus $6.19 for each additional $1,000.00 or fraction thereof
Building Permit Fee — valuation $1,000,001.00 and upTown of Darby Building Permit Fee Schedule
$7,010.94 for the first $1,000,000.00, plus $4.56 for each additional $1,000.00 or fraction thereof
Commercial-specific Plan Review / Plan-Check Fee
Checked the Town of Darby Building Permit Fee Schedule (Res. Show full citationChecked the Town of Darby Building Permit Fee Schedule (Res. 649, updated 4/13/2021) and the Building Permit Application (amended 2022-03-23) directly: neither publishes a commercial plan-review percentage of the kind Ammon (10%) or Buhl (50%, capped 65%) charge. The Fee Schedule's only review-adjacent charge is a general 'Additional plan review required by changes, additions or revisions to plans' line, billed hourly (see next fee line), applicable to any Darby permit type, not a commercial-specific plan-check fee
Not published as a distinct charge
Additional Plan Review (changes/additions/revisions to submitted plans)Town of Darby Building Permit Fee Schedule, Other Optional Inspections and Fees section, item 4
$47.00 per hour minimum, half-hour minimum increment, or the total hourly cost to the jurisdiction, whichever is greater

Review timeline

Plan review
Not published — contact the department

How long did your Commercial Building Permit (New Construction, Addition, Alteration, Repair) permit actually take in Darby?

Anonymous — one question, no email. Answers are combined and only shown once at least 5 people have reported.

Inspection process

    Tips

    • Darby's Building Permit Application and Building Permit Fee Schedule do not distinguish commercial from residential work — the same form, the same valuation-based fee table, and the same design-criteria table apply to a commercial structure as to a house.
    • The Town's own Building Permit Flyer (effective September 16, 2021) states the Town 'has adopted ALL applicable building related codes for RESIDENTIAL & COMMERCIAL,' alongside Electrical, Plumbing, Mechanical, Fuel Gas, and Swimming Pool/Spa — confirming commercial work is covered by the Town's own certified program, not routed to the state.
    • No commercial plan-review or plan-check percentage fee is published; the closest analog is the Town's general $47.00/hour charge for additional plan review triggered by changes to submitted plans, which applies across permit types rather than being scoped to commercial work.
    • For fire-district input on a commercial project, contact the Darby Volunteer Fire Department directly (non-emergency (406) 821-3100) — no formal fee or process specific to fire review of a commercial building permit is published by the Town.

    Frequently asked questions

    Darby requires a commercial building permit (new construction, addition, alteration, repair) for: Building permit required for new construction, additions, alterations, repairs, and other structural work on a commercial building in Darby; Filed on the Town's general Building Permit Application — the form has a single 'Describe nature of the project and the building use or occupancy' field and a 'Type of Work' checklist (New/Addition/Alteration/Repair/Mobile Home/Re-Roof/Demolish/Other) with no separate residential/commercial track; Provide a plot plan showing building location and distances from each side of the lot, indicating alleys or streets; Provide 2 sets of plans drawn to scale, including foundation, floor and roof framing, floor plans, and exterior elevations (one set may be submitted digitally); All work must conform to the most current adopted building codes (IBC, IRC, IEBC, ISPSC, IECC, NEC, IMC, IFGC, UPC) and Montana Administrative Rules (A.R.M.), plus applicable local codes; Design criteria compliance: 46.0 psf ground snow load, 112 mph wind speed, Seismic Design Category C, severe weathering, 36-inch frost line depth, required ice shield underlayment; Setback compliance: occupied buildings 25 ft front/rear, 5 ft sides (15 ft corner lot); accessory buildings 25 ft front, 7.5 ft rear, same side setbacks as occupied buildings. If your project isn't listed, confirm with Town of Darby Building Department at (406) 821-3753 before starting work.

    No. Darby's Building Permit Fee Schedule has one valuation-based table used for any structure, commercial included, and no commercial-specific plan-check percentage is published — unlike Ammon (10% of the permit fee) or Buhl (50%, capped at 65%). The Town's only review-related charge is a general $47.00-per-hour fee for additional plan review triggered by changes to submitted plans.

    Darby does not publish a plan-review timeline for this permit. Contact Town of Darby Building Department at (406) 821-3753 for current turnaround.

    You'll need: Building Permit Application; Plot Plan; Construction Drawings (2 sets). See the required-documents checklist on this page for details on each.

    Apply through Town of Darby Building Department at 101 E Tanner Ave / PO Box 37, Darby, MT 59829. Phone: (406) 821-3753, email: darbymontana@usa.net. Office hours: Town Hall: Monday-Friday, 8:00 am - 5:00 pm. Source: Town of Darby Contact Us page (darbymt.net/a/contact-us/). Building permit applications and fee payment are handled in person at Town Hall; the current contracted building inspector is Construct Montana, LLC, (406) 552-3238, inspector@constructmt.com; the Montana DLI-certified program contact of record is Tim Netzley, (406) 961-2423 (also listed as (406) 880-5832 on the Town's own Building Permit Application form).. Official information: https://www.darbymt.net/a/building-related-code/.

    Darby, Montana has adopted: Montana has a mandatory statewide building code administered by the Montana Department of Labor & Industry (DLI) Building Codes Bureau, amended by the Administrative Rules of Montana (ARM) Title 24, Chapter 301. Cities, counties, and towns may become 'certified' to locally administer permitting and inspection for all or part of the code; a certified local program's adopted code 'may include only codes adopted by the Building Codes Bureau' (ARM 24.301.202). Non-certified areas fall under direct state administration by the DLI Building Codes Bureau. Source: Montana DLI Building Codes Bureau, Certified City, County and Town Programs page (bsd.dli.mt.gov/building-codes-permits/certified-government).; Darby is a Montana DLI-certified jurisdiction for Building (B), Plumbing (P), Mechanical (M), Electrical (E), and Swimming Pool (SP) — full trade certification — within Darby town limits ('City Limits' jurisdiction scope). Certified program contact on file with DLI: Tim Netzley, (406) 961-2423. The DLI's official 'Certified City, County and Town Programs' roster PDF (updated 2026-04-22) reads 'Darby | B, P, M, E, SP | Tim Netzley | 961-2423 | City Limits'. Source: https://bsd.dli.mt.gov/_docs/building-codes-permits/certified-city.pdf; The Town's own Building Permit Application states: 'All work shall conform to the most current building codes - IBC, IRC, IEBC, ISPSC, IECC, NEC, IMC, IFGC, UPC and Montana A.R.M; and applicable local codes' and 'Electrical, Plumbing, Mechanical permits are applied for and inspected by Town of Darby, effective September 16, 2021.' Source: Town of Darby Building Permit Application (amended 2022-03-23), https://www.darbymt.net/a/wp-content/uploads/2022/03/Building-Permit-Application-amended-2022-03-23.pdf; Montana uses the Uniform Plumbing Code (UPC), not the International Plumbing Code — confirmed on Darby's own Plumbing Permit Application, which requires a licensed Master Plumber 'in accordance with Title 50, Chapter 60, Section 505, MCA and Sections 8.70.302, 8.70.303, 8.70.304, and 8.70.305 ARM' and states 'All provisions of the Uniform Plumbing Codes and the International Building codes will be strictly enforced.' Source: Town of Darby Plumbing Permit Application (2023-08-22), https://www.darbymt.net/a/wp-content/uploads/2023/08/Plumbing-Permit-Final-TOD-2023-08-22.pdf; State-adopted code editions in effect statewide since June 11, 2022 (per DLI Building Codes Bureau, applicable as the baseline Darby enforces as a certified jurisdiction): 2021 IBC, 2021 IRC, 2021 IEBC, 2021 IMC, 2021 IFGC, 2021 IECC, 2021 UPC, 2020 NEC, 2021 ISPSC. Source: Montana DLI Building Codes Bureau, Current Codes page, https://bsd.dli.mt.gov/building-codes-permits/current-codes. Darby's own permit application does not list specific code-edition years locally; no local re-adoption ordinance/administrative order text was found published online (Town Hall does not publish a codified municipal code online) beyond the applications' own reference to 'most current building codes'.. Local amendments apply — see the Darby overview page for the full list.

    The Town issues its own. Darby's Montana DLI certification covers Building, Plumbing, Mechanical, Electrical, and Swimming Pool with no residential-only qualifier, per the DLI's Certified City, County and Town Programs roster, and the Town's own Building Permit Flyer confirms it has adopted codes for 'RESIDENTIAL & COMMERCIAL' work alike.

    Sources & verification

    Verified against official sources. Last reviewed 2026-08-26.

    Fee schedules

    Applications & forms

    Codes & ordinances

    Department & other records

    Fees, timelines, and adopted codes are researched from each jurisdiction's published records — see how we verify. Requirements change and vary by project, so always confirm the current details with the Darby building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.

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