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Montana WUI code status
Montana adopts a modified 2021 IWUIC, then leaves enforcement to a local election. ARM 24.301.181 incorporates the 2021 edition with Appendix B (vegetation management plan) and Appendix C (fire hazard severity form). The Department of Labor and Industry lists that Wildland Urban Interface Code as a current adopted code, effective 11 June 2022.
You are looking at a lot in Montana and asking which book binds a new roof. The ARM is not self-executing on every lot. Cities, counties, and towns that adopted the IBC or IRC will, if they elect to enforce the IWUIC, record official wildland-urban interface areas on maps available for inspection. Ask the building official whether that election happened, and whether your lot is on that map. This site does not read your parcel.
Why it matters
A “Montana adopted IWUIC” search result is not a Class A roof. Chapter 4 is gone. Section 602 automatic sprinklers are gone. Remaining Chapter 5 construction uses a replaced ignition-resistant table. Oregon R327 and California CWUIC are different books.
How it works
ARM 24.301.181(2) replaces Section 302. The governmental body or another official state or local agency shall declare WUI areas. That declaration may rest on mapping, boundary designations, or wildland fire plans.
These are the amendments that change the construction conversation:
| ARM 24.301.181 | What it does |
|---|---|
| (3) | Deletes Chapter 4 in its entirety |
| (5) | Deletes retroactivity |
| (7) | Deletes maintenance |
| (21) | Replaces Table 503.1 (ignition-resistant construction) |
| (22) | Deletes Section 602 automatic sprinklers |
| (23) | Deletes Section 604 maintenance of defensible space |
The replaced Table 503.1 still points at IR 1, IR 2, and IR 3 classes, scaled by defensible-space category and hazard. It is not unmodified 2021 IWUIC Table 503.1. Spec the ARM table if the local official is enforcing this book.
The paths
- Local election to enforce the Montana IWUIC. Spec ARM 24.301.181 plus the local WUI map.
- No local election. Ordinary IBC or IRC construction. Harden anyway. IBHS is a designation, not adopted code.
- Do not import Chapter 4 access or Section 602 sprinklers from the model PDF. Those sections are deleted in Montana.
What people mix up
- Treating DLI’s adopted-code list as a permit on an unmapped lot.
- Specifying unmodified 2021 IWUIC Chapter 4 or 602 in Montana.
- Importing Oregon R327 or California CWUIC onto a Montana drawing.
How to check
- Ask the building official whether the city or county elected to enforce the IWUIC, and whether a WUI-area map exists.
- Open ARM 24.301.181 and DLI Current Codes.
- If a local map exists, use that official map. Do not treat this page as a lot determination.
Limits
This page does not decide a permit. It does not quote a county map we have not opened. Listed OSFM products are California listings unless the local official accepts them.
Related records
- IWUIC model book and Montana diffs
- How WUI is mapped
- Idaho WUI code status for a neighboring state with no statewide IWUIC
Questions
Does Montana require IWUIC construction on my lot today?
Not automatically. ARM 24.301.181 adopts the 2021 IWUIC with amendments. Cities, counties, and towns that have adopted IBC or IRC will, if they elect to enforce the IWUIC, record WUI areas on public maps. Confirm with the building official.
What did Montana delete from the model book?
ARM 24.301.181 deletes Chapter 4 (access, water, and related WUI-area requirements) and Section 602 (automatic sprinklers). It also deletes retroactivity, maintenance, and defensible-space maintenance sections, and it replaces Table 503.1. Remaining Chapter 5 construction is not unmodified IWUIC.
Where is the official map?
The ARM tells the local jurisdiction that elects to enforce the code to record WUI areas on maps available for inspection. This site does not host those maps and does not read your parcel.