Current Building Codes (301)

Currently Adopted Building Codes

Revised and updated to apply to projects submitted on or after January 1, 2018.

  • 2015 International Building Code (IBC) (Including Appendix H – Signs and Appendix J - Grading)
  • 2015 International Existing Building Code (IEBC)
  • 2015 International Residential Code (IRC), parts I through IV and IX, (Including Appendix S – Strawbale Construction and Appendix V – Tiny Homes), (2012 IRC amended)
  • 2015 International Energy Conservation Code (IECC)
  • 2017 Idaho State Plumbing Code (Including Chapter 13 – Medical Gas); based on the 2015 Uniform Plumbing Code (UPC)
  • 2017 National Electrical Code (NEC)
  • 2015 International Fire Code (IFC)
  • (Voluntary – not required) 2012 International Green Construction Code (IgCC) (Including Appendix A – Project Electives)
  • International Code Council Free Online Library


Mechanical Codes

Commercial projects and all residential projects with more than two units:

  • 2012 International Mechanical Code (IMC) (Including Appendix A)
  • 2012 International Fuel Gas Code (IFGC) (Including Appendices A, B, C, and D)

Residential projects with one or two family dwellings:

  • 2012 International Residential Code (IRC) (parts V, VI and Appendices A, B, C, and D)


2015 IBC Basic Design Criteria

  • Ground Snow Load = 20 psf (pg)
  • Uniform Roof Snow Load = 25 psf (pm) Local amendment language, including clarification on drifting, to IBC Sections 1605.2, 1605.3.1, 1608.1 and 1608.2 can be viewed here.
  • Ultimate Design Wind Speed (3 second gust) Using IBC Figures 1609.3(1), 1609.3(2) and 1609.3(3). Exposure category per IBC Section 1609.4
  • Frost Depth = 24 inches minimum (local amendment to IBC)
  • Rainfall Rate = 1 inch per hour minimum (per Idaho State Plumbing Code and IBC Section 1611)
  • Earthquake Loads (IBC Section 1613)
    Use this basic procedure to determine the Seismic Design Category:

Step 1: Determine the mapped maximum considered earthquake spectral response acceleration at short periods (Ss), and at 1-second period (S1), for the site location from IBC Figures 1613.3.1(1) through 1613.3.1(8).

Step 2: Determine the (soil) site class in accordance with Chapter 20 of ASCE 7.

Step 3: Determine the site coefficients Fa and Fv from IBC Tables 1613.3.3(1) and 1613.3.3(2), respectively.

Step 4: Determine the 5-percent damped design spectral response acceleration at short periods (SDS) and at 1-second period (SD1) as follows:

SDS = (2/3)(SMS)
SD1 = (2/3)(SM1)

Step 5: Determine the seismic design category as prescribed by IBC Tables 1613.3.5(1) and 1613.3.5(2). The highest of the seismic design categories from the two tables is the category assigned to the building, unless Section 1613.3.5.1 is applicable.

Revised December 2017

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