Fence Post and Footing Design Guide for Wind and Ice Loading

Fence posts and post footings are structural elements that are used to support the body of a fence and resist a variety of environmental loads.  They are expected to remain plumb and undamaged for decades with little to no maintenance.  The post and footing’s ability to do this is affected by a wide range of factors that all need to be considered to ensure a long service life.

Considered “non-building structures”, the design of fence posts and post footings are often relegated to design by rules of thumb that do not take into consideration site-specific environmental factors, soil strengths, and the aerodynamic properties of the fencing materials.

Why use this Guide?

Sizing of fence posts and post footings is a topic that has few available resources, and what is available is mostly decades out of date and often incorrect.  This includes published data from manufacturers and trade groups.

• Building codes do not directly address fencing design and the available design data has to be interpreted & translated to properly size posts and footings.
• Published strength data for metal tubular fence posts is typically around 15% lower than the actual values under modern codes.
• Published strength data for roll formed hat and c channel posts are calculated using the wrong design standard.
• Actual wind area of chain link mesh can be anywhere from 9% lower to 20% higher than published data.
• There are no widely available published methods for determining wind force coefficient, C_f values for fence posts near ends and corners.
• Post footings design information in the building codes is not worded clearly and is easily misinterpreted.
• Modern codes require ice loading for around 95% of the US, but it is typically neglected in fencing design.

The information provided in this guide is based on the currently used building codes and reference standards in the United States, and standard structural engineering methods.  Using modern design methods, fence posts and post footings can be specified that are more economical in labor and materials, increase the service life of the fence, and decrease liability for installers.

Disclaimer

The materials set forth herein are for general information only.  They are not a substitute for competent professional advice.  Application of this information to a specific project should be reviewed by a registered professional engineer.  Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.

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