Roofing Permit (Reroof) in Helena, Montana
VerifiedRequired for installation of new roofing materials and replacement of roofing materials (re-roof) on one- and two-family dwellings within Helena city limits. The City of Helena Building Division is the Authority Having Jurisdiction under 2021 IRC Chapters 8 and 9; structures of three dwelling units or more and all commercial structures are instead regulated under the 2021 IBC Chapter 15.
Verified 2026-07-02 · Source
When you need this permit
- Roof replacement must include removal of all existing layers of roof covering and underlayment down to the roof deck (2021 IRC R908.3), except where an existing adhered ice-barrier membrane may remain and be covered with an additional layer
- Installing a new roof covering OVER an existing roof covering is permitted only where 2021 IRC Section R908.3.1 compliance is followed — contact the Building Division for requirements
- Ice barrier underlayment required per Montana DLI Technical Advisory T1-16 and 2021 IRC R905.1.2: at least two layers of cemented underlayment or a self-adhering polymer-modified bitumen sheet, extending from the lowest roof edges to at least 24 inches inside the exterior wall line (exception: unconditioned detached accessory structures)
- Attic/rafter space ventilation required per 2021 IRC R806.1-R806.3: minimum net free ventilating area of 1/150 of vented attic space (or 1/300 with a Class I/II vapor retarder and proper ventilator placement)
- Drip edge required at eaves and gables per 2021 IRC R905.2.8.5, overlapped minimum 2 inches, extending minimum 0.25 inch below roof sheathing and 2 inches up the roof deck, mechanically fastened at maximum 12 inches on-center
- Flashing must be installed per approved manufacturer instructions to prevent moisture entry at walls, parapets, and roof penetrations (2021 IRC R903.2 and R908.6)
Required documents
- Required
Re-Roofing Application
City of Helena Building Division application for roofing repair/replacement
- Optional
Roofing and Re-Roofing Code Requirements (2021 IRC)
City of Helena's own summary of the applicable IRC ventilation, ice-barrier, drip-edge, and flashing code sections for one- and two-family dwellings
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| Roofing Permit Fee — valuation-based | Per Ordinance 3134 Building Permit Fee Tabulation table (same table used for building permits generally) | City of Helena Building Permit Types page directs roofing fees to the same 'Building and Plan Review Fees' PDF/table used for other building permit categories; no distinct flat re-roof fee schedule is published separately |
Review timeline
~1–3 business days
Typical estimate — confirm current times with the Helena building department
Inspection process
- 1
Final (Roof)
Verifies drip edge, ice barrier underlayment, flashing, and ventilation per 2021 IRC Chapter 8/9
Tips
- Roofing over an existing roof covering (rather than tearing off down to the deck) is only allowed under specific 2021 IRC R908.3.1 conditions — confirm with the Building Division (406-447-8438) before planning an overlay re-roof.
- Ice barrier underlayment is a hard Montana DLI Technical Advisory T1-16 requirement in Helena given its winter climate and ice-damming history — budget for it on every re-roof unless your structure qualifies for the unconditioned-accessory-structure exception.
Frequently asked questions
- What code applies to re-roofing a house in Helena?
- The 2021 International Residential Code (IRC), Chapters 8 and 9, for one- and two-family dwellings, enforced by the City of Helena Building Division. Structures with three or more dwelling units and commercial buildings instead follow the 2021 International Building Code (IBC) Chapter 15.
Sources & verification
Verified against official sources. Last reviewed 2026-07-02.
- City of Helena — Community Development Department, Building Division — official building department
- City of Helena — Roofing and Re-Roofing Code Requirements (PDF, November 2022)
- City of Helena — Building Permit Types (Roofing section)
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 Helena building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.
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