Codes & Design Requirements

PLEASE NOTE, beginning March 25, 2020, the City of Helena Building Division will enforce the 2018 edition of the International Codes and the 2017 edition of the National Electrical Code along with the State of Montana, Administrative Rules amendments and as amended in City Code, Title 3.  All permit applications received on or after March 25, 2020 will be reviewed under the newly adopted codes. For more information see Open Letter of Final Adoption or contact the City Building Division at (406) 447-8438. 

The Building Codes listed below are effective as of March 25, 2020.  The codes have been adopted and amended by the Administrative Rules of Montana (ARM) Title 24, Chapter 301, and adopted by the City of Helena in Title 3 of the City Code.

Design Requirements

  • Seismic Design Category according to the 2018 International Building Code (IBC), typically D0 or as calculated by International Building Code, Chapter 16 based on site specific soil conditions.
  • Wind Load - f 3s - 90 mph, f fm - 75 mph
  • Snow Load - (ground/roof) 30 lbs psf minimum
  • Frost Depth - 42" minimum to bottom of footing
  • Ice and Water Barrier Under-layment Required – Yes