Wind and Ice Values

The IBC defers to The American Society of Civil Engineers (ASCE) to determine wind and ice forces.  The standard referenced by the IBC is ASCE 7 – Minimum Design Loads for Buildings and Other Structures.

The applicable version of ASCE 7 depends on which version of the IBC that is adopted by the local building code.

  • For IBC 2012 & 2015     use     ASCE 7-10
  • For IBC 2018 & 2021     use     ASCE 7-16
  • For IBC 2024 & 2027     use     ASCE 7-22

Research and testing are being done continuously, so each version of ASCE 7 has different wind and ice values for a given site location.  This information can be found online at:  https://ascehazardtool.org

To use the online ASCE 7 Hazard Tool:

  1. Close the welcome message.
  2. Enter the address or the latitude and longitude for the installation site and press “Search”.
  3. Pick the appropriate version of ASCE 7.  (-10, -16 or -22)
  4. Select a Risk Category.  Fences typically fall under Risk Category I, but the client may specify a higher Risk Category (e.g. II, III or IV) which would increase the forces.
  5. Site Soil Class can be ignored as this is only used for seismic calculations which are beyond the scope of this design guide.
  6. Pick the wind and ice check boxes and click “View Results”.
  7. The wind speed in miles per hour and nominal ice thickness in inches will be shown on the screen. 
  8. Click “Details” for ice to get the 3-second Gust Speed required for ice loading.

For example, for Houston, TX, IBC 2021 / ASCE 7-16, Risk Category I, the values are:

                        Basic Wind Speed, Vw                 128 mph

                        Nominal Ice Thickness, t             1.00 in

                        Concurrent / Gust Speed, Vi       30 mph

If there are not published values due to local geography, the values will have to be supplied by the local building authority.

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Next – Wind Pressures