Outdoor steel structures and their protection from the elements

Outdoor structures made of metal are solid, durable and easy to protect from the elements. Structural steel is the most common metal used for making outdoor structures. In industrial conditions, outdoor structures are also made of aluminum, stainless steel and various alloys. In this article we will only deal with outdoor steel structures.

Structural Steel is the most common metal used for making outdoor structures at home because it is inexpensive, sturdy and easy to weld. The disadvantage of structural steel is its susceptibility to corrosion. There are several ways to protect your outdoor structure made of structural steel. The principle of corrosion protection is based on the insulation of metal surfaces in aggressive environments. Protective coatings by their origin may be non-metallic and metallic.

Corrosion protection in industrial conditions

The most common methods of protection against corrosion of steel structures in industrial conditions are:

- Galvanizing – a method that comprises applying a protective metal coating to the surface made of some other metal. By galvanizing steel we usually consider the process of applying a thin zinc coating. One good characteristic of galvanization is that, when the zinc surface is damaged, there is no corrosion of steel. Steel begins to rust only when it becomes exposed to the external environment i.e. when  the zinc coating is completely damaged.

 - Powder coating - Powder coat finish is achieved by applying the powder electrostatically to the structure and by baking at high temperature. In this way, a thin protective coating on the metal surface is obtained. Steel structures can be coated with metal powder (zinc or aluminium), plastic powder or concrete powder. Powder coating is a quality method of protecting steel structures against corrosion, but its disadvantage is that if the protective coating gets even slightly damaged, steel gets in contact with the external environment and starts to corrode.

Corrosion protection at home

Coating of steel structures with different paints and varnishes is the most common method in order to protect steel structures at home and if done well, it will last for decades (with adequate maintenance). There are many types of metal paints and if you have no experience, consult with an experienced handyman or conscientious seller before buying. Follow the directions given by the manufacturers on the containers.

Before applying any coating, the surface of the metal should be thoroughly cleaned. The most effective preparation of metal surfaces is done by fine sandblasting. If this method is not possible, then  wire brushes, sandpaper or anti-corrosion chemicals may be used.

Such a prepared surface is treated with first coat primer. When this basic paint becomes dry, the structure is coated with metal paint.

There are various types of primers and metal paints, read the given instructions carefully before applying (how many layers, whether it is necessary to dilute the primer/paint, drying time, resistance to external influences etc.).