Montana Ground Snow Load by County and Town

Montana adopted a snow load study, and that study carries the values, Snow Loads for Structural Design in Montana (Revised 2004), through Civil Engineering Department, Montana State University. twelve of its published figures are set out below with the row each was read from. Only 14 states out of 50 publish anything of their own like it; the other 36 send a reader either to the national code or to a county counter. twelve Montana figures, running from 19.2 psf at Dillon AP to 410.7 psf at North Fork Jocko, every one of them quoted from the document it was printed in. Nationally 235 figures were read across 33 states.

Montana Department of Labor & Industry, Building Codes Program (Building and Commercial Measurements Bureau): the building official, which inside a certified city, county or town is that jurisdiction's own official and elsewhere is the state bureau. In its own words: “For areas inside a certified city, county, or town jurisdiction, snow load information shall be obtained from the building official of the certified jurisdiction unless it is a state-owned agency which must be permitted through this Department.”

Part of Montana is a case study area, meaning the published document expressly declines to give those places a figure and sends the designer back to the local building department for one. 16 states carry a rule like this, and it is the commonest reason a search for a single number comes back empty. The rule reads: “For areas not listed, not of the same elevation as listed, or locations having some other variable, ground snow loads should be determined by calling the State Building Codes Bureau at (406) 841-2056.”

The figure moves with elevation in Montana, which is the hardest case for a reader: two houses a mile apart and a thousand feet apart take different numbers, and 13 states are keyed this way. The published Montana figures run from 19.2 psf to 410.7 psf.

Montana Department of Labor & Industry, Building Codes Program adopts International Residential Code (2024 Edition). Montana amended it rather than adopting it whole, and 22 states have done the same. The adopting rule reads: “All of the codes listed below are amended and adopted by: Administrative Rules of Montana (ARM) Title 24, Chapter 301”

A ground snow load is a weight per unit area and not a depth, and the two are joined only by the density of the snow on the day, which is why the published documents give the load and leave the depth out. Wet spring snow and dry January snow of the same depth are different weights on the same roof. Montana Department of Labor & Industry, Building Codes Program (Building and Commercial Measurements Bureau) works in loads for that reason, and so does every figure set out below.

The Montana document itself is the place to look a town up, and what it prints is applied by Montana Department of Labor & Industry, Building Codes Program (Building and Commercial Measurements Bureau). The document behind it is Snow Loads for Structural Design in Montana (Revised 2004), published by Civil Engineering Department, Montana State University, read on September 23, 2026. It establishes the point this way: “Snow loads shall be determined by the building official. All state-owned agencies and area of the state outside of certified city, county and town jurisdictions, the design snow load shall be based on the utilization of the ASCE 7 Hazard Tool.”

14 of 50: Connecticut, Indiana, Maryland, Massachusetts, Michigan, Minnesota, Montana, New Hampshire, New Jersey, North Carolina, Rhode Island, Utah, Vermont, Wisconsin. The other 36 split into 17 that adopt the national code without a snow amendment and 19 that leave every figure to a county or city building department. That is the single most useful fact about this subject and no one state's own website carries it.