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Design Criteria & Codes

Current Adopted Building Codes

  • 2021 International Building Code and Amendments
  • 2021 International Energy Conservation Code and Amendments
  • 2021 International Mechanical Code and Amendments
  • 2021 International Plumbing Code and Amendments
  • 2021 International Residential Code and Amendments
  • 2021 Fire Code and Amendments
  • 2021 International Fuel and Gas Code
  • 2020 National Electrical Code
  • 2017 Accessibility Code


The City of Lone Tree’s incorporation was approved by voters in November of 1995. From November 1995 until September 1996, Douglas County still had jurisdiction and was on the 1991 UBC family of codes.

  • In September 1996, the City adopted the 1991 UBC family of codes and the 1993 NEC
  • In November 1999, the City adopted the 1997 UBC family of codes and the 1999 NEC
  • In November 2009, the City adopted the 2006 ICC family of codes and the 2008 NEC
  • In November 2011, the City adopted the 2009 ICC family of codes and the 2011 NEC
  • In January 2015, the City adopted the 2012 ICC family of codes and the 2014 NEC
  • In January 2019, the City adopted the 2018 ICC family of codes and the 2017 NEC
  • In January 2021, the City adopted the 2020 NEC
  • On January 1, 2023, the City will adopt the 2021 ICC family of codes
    • SNOW LOAD
      • Roof Snow Load – 30psf
    • WIND LOAD
      • 90 MPH 3 sec gust – Exposure C
    • SEISMIC DESIGN
      • Seismic Design Category: IRC: B
      • Seismic Design Category: IBC: Per chapter 16
    • CLIMATIC CONDITIONS
      • Heating Degree Days: 6343
      • Winter Design Temperature: -3 F
      • Summer Dry Bulb 90 F
      • Summer Wet Bulb 59 F
      • Air Freezing Index 867
      • Mean Annual Temperature 48.1 F
      • Minimum Frost Depth for Foundations 36 inches
    • COMMERCIAL FLOOR LOADS
      • IBC table 1607.1
    • RESIDENTIAL FLOOR LOADS
      • Live load 40psf (30psf in sleeping areas) see table R301.5
      • Dead Load 10psf
      • Duration of Load 1.00
      • Deflection L/360
    • ROOF LOADS
      • Live Load 30psf (attic=”10psf” no storage, 20psf limited storage)
      • Dead Load 10psf Minimum or as required based on type of roofing material and ceiling material, see table R301.6
      • Duration of Load 1.15 (Snow)
      • Deflection L/180 Rafters (no ceiling); L/240 (ceiling); L /240 Beams, see table R301.7
    • DECKS
      • RESIDENTIAL EXTERIOR DECKS: 40psf Live Load (LL), see table R301.5
      • COMMERCIAL EXTERIOR DECKS: see table 1607.1

     In addition to the above, the building department may request additional data, calculations or information deemed necessary to confirm compliance with code requirements.



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