Design of Cable Railing Systems
Cable railing systems are often installed in residential and commercial settings. They can also be found in a wide variety of architectural applications and are becoming increasingly popular for use on boats and other recreational vehicles. Like other types of handrails and guardrails, cable railing must be designed to meet specific code requirements. These standards typically require a certain amount of post spacing and cable diameter, but can vary slightly from area to area. Before beginning a project, it is important to know these stipulations and how they may impact the design of your cable railing system.
The most common diameter for cable railing is 1/8” diameter. This size can be used on both vertical and horizontal runs of cable and is generally sufficient for most applications. In some cases, however, a thicker diameter cable is required, particularly in areas subject to heavy shock loads. In these situations, 3/16” diameter cable is usually the chosen option. The additional strength provided by the larger cable diameter helps to reduce the potential for cable failure due to shock loads and excessive force.
Most of our cable railing supplies are made with type 316 stainless steel, a material known for its strength and corrosion resistance. The specific grade of stainless used is determined by the application and environment. If the system is located outdoors, a marine-grade stainless is recommended to help prevent rust and corrosion. Indoor applications can be accommodated with standard residential grade stainless.
How Cable Diameter Options Affect the Design of Cable Railing Systems
In addition to the type of steel used, there are a number of other factors that determine the best size of cable for a particular application. There are also many different constructions of cable (also referred to as wire rope). Some are designed to be flexible for going over pulleys while others, such as guy wire or sailboat stays, are intended to be more rigid with less flexibility.
One of the most important things to consider when choosing a cable for a railing is the minimum tensile strength. The higher the tensile strength, the stronger the cable will be.
While it is possible to build a cable railing system using a lower-strength cable, this will not be sufficient for most uses and will quickly fail under load. It is highly recommended that all cable used for railings be of the minimum tensile strength specified.
Another factor that influences the stiffness of cable is the amount of space between posts. Guidelines recommend that openings not exceed 4” and that the spacing between posts should be at least 3 feet on center. This minimizes deflection between cables and facilitates compliance with the sphere rule.
A final consideration when choosing a cable for a railing system is how it will be terminated. Most systems use an end fitting, which is swaged onto the cable at one of the end posts. To keep the cables in line and on the same plane, we suggest angling the hole in the end post up from one side and down from the other to offset the cables by the proper amount.