We frequently get asked what is the best material for a cable railing system at CityPost. The answer is that it depends on climate, budget and aesthetics. There are essentially 4 materials that have been traditionally used for cable railing posts: wood, aluminum, carbon steel and stainless steel.
All of the metal posts can provide long lasting, maintenance free solutions unlike wood posts which need to be stained and painted periodically which is commonly understood by customers. Clearly metal is the way to go in this category but amongst aluminum, steel and stainless steel the choice is less obvious. In general, cable railings use Stainless steel 316 cables and fittings. 316 means that the steel has a 2-3% molybdenum content for surviving in the harshest environments. Both aluminum and zinc plated or galvanized steel can work well with the stainless 316 fittings in most environments. Aluminum suffers from slightly more galvanic corrosion when in contact with the fittings compared to galvanized. The decision on this is fairly simple at the end of the day: use stainless steel posts in coastal environments or anywhere exposed to salt and otherwise use zinc plated and powder coated posts for general cases.
The least expensive initial investment is typically a wood post but when you couple maintenance costs and installation labor things change dramatically. Wood posts need blocking and tension tie backs installed in accordance with the IRC and will need painting or staining every few years. Metal posts are much more economical from a labor perspective and can typically be installed in minutes once layout is complete. The cost of metal posts varies significantly by material type. Typically aluminum is the least expensive as the bulkier look occupies the lower end picket market. Galvanized steel is slightly more expensive than aluminum and Stainless Steel can easily reach double the cost of aluminum or galvanized steel.
In general cable railing is designed to minimize how much of the view is blocked so slender posts are desirable. The easiest way to look at the strength of a solution is the elasticity of a material: Wood 1.6 Mpsi, Aluminum 10 Mpsi and Steel 30 MPsi. Since steel has 20x the strength of wood and 3x the strength of aluminum much more slender posts are possible. 2” thick material is appropriate with steel instead of 3 and 4” posts which block much of the view.
Low Maintenance and long service life with traditional cable railing looks -> Galvanized Steel with powdercoat
Ultra Low Maintenance for marine environments -> Stainless steel (bare or powder coat)