Outdoor metal stairs: Guide to materials and finishes

Outdoor metal stairs are widely used in a variety of settings due to their versatility, low maintenance and high durability. These types of stairs are commonly seen in apartment buildings, but also have a many industrial uses including roof, tank, HVAC, equipment and loading dock access.

outdoor galvanized stair

When selecting outdoor metal stairs, one should understand the different configurations, finishes and treads available. This guide will help you understand these options.


Outdoor metal stairs can be constructed in a single unit or designed as a permanent, free-standing stair tower. Both standard stairs and alternating stairs can be used in either configuration.

Standard prefab metal stair units can lower design and shipping costs. These stairs are easy to assemble, even in compact spaces, with no welding required. A good example of an application for a single metal stair unit is for loading dock access.


Alternating tread stairs provide additional safety and comfort to the user. With standard stairs, each foot normally uses only about half of each tread, stepping out and over the unused section. With alternating tread stairs, the unused half tread is removed to provide more tread depth. IBC allows alternating tread stairs to be used for unoccupied roof access. They can also be used under OSHA rules for equipment access, roof crossovers, and other outdoor applications. 


ith stair towers, each single stair unit is assembled and then the tower is created by stacking and bolting the units

 together at the base plates for easy alignment. Modular, permanent, code-compliant, stair towers are designed to save time and money over custom-designed stair towers. Common uses for stair towers include roof, tank, and equipment

 access. Stair towers can be comprised of either standard or alternating tread stairs.



Several different types of finishes are available for outdoor metal stairs including galvanized steel, power coated metal and aluminum. Let’s look at the benefits and uses for each of these finishes.

Galvanized steel is made by dipping carbon steel into molten zinc to obtain a thin coating which bonds to the steel to prevent rust from forming. This long-lasting zinc coating prevents corrosive substances, like acid rain, from reaching the steel below the coating.

Galvanization protects the metal from rust and corrosion much longer than paint, often for 50 years or more. Even if the coating is scratched, the zinc will still protect the metal base from rusting because it corrodes faster than the metal below it.

Powder coated metal features finely ground particles of pigment and resin used to create a protective finish that helps prevent corrosion. To create a magnetic attraction, the pigment and resin are charged with static electricity and then sprayed onto steel that is electrically grounded. The powder coating is then evenly melted and cooled into a thin, durable film.

Powder coating can provide an economical and color-durable finish, but it is not as corrosion resistant as galvanized steel. Powder coating typically lasts only 15-20 years, depending on the pre-treatment of the metal and the type of powder used.

Aluminum is a metal which is naturally corrosion resistant without any further treatment. It is lighter than steel, but not as weather resistant. Aluminum can last for more than 30 years.

For outdoor metal stairs, Lapeyre Stair recommends galvanized steel over other finish options. It’s strength and durability make it the most weather resistant option. However, because aluminum is lightweight, it can be a good option when weight is a factor, such as with roof stairs. Aluminum might also be preferred over galvanized steel due to its antibacterial properties in some environments, including those used for food processing.


In addition to selecting the right finish for outdoor metal stairs, one should also consider the best kind of tread for the application. Several options exist including non-slip treads with abrasive coatings, diamond plate treads, bar grating treads and grip treads.

The safety of outdoor metal stairs can be improved with non-slip treads which eliminate slippery conditions. Typically, the treads are covered with a light-weight, bolt-on tread cover which features a permanent, abrasive polyurethane coating. This option is cost effective, as well as sound dampening and is typically available in a variety of custom powder coat colors. Non-slip treads can be used in dry or wet industrial settings which need higher slip resistance or noise control.

diamond-plate-treadDiamond plate treads feature a pattern of raised diamond on one side with the reverse side being smooth. The added texture of diamond plate treads reduces the risk of slipping, making it an option for outdoor metal stairs. Drain holes can be added to reduce the collection of water or liquids on the surface but diamond plate treads are best used for dry, low traffic areas.


Bar grating treads feature an open grid assembly of metal bars. Bearing bars, which run in one direction, are spaced by rigid attachment to cross bars running perpendicular to them or by bent connecting bars extending between them. Bar grating treads are good for wet, exterior environments and for stairs that require light, liquid, air, heat, and sound to pass between flooring levels.

grip-treadGrip treads feature a serrated surface which help reduce accidents by providing a safer walking and working surface. The serrated surface is designed in an open diamond pattern, allowing drainage of fluids, mud, chips, and other accident-causing debris. Grip treads provide maximum slip protection under practically all conditions and in every direction. Grip treads are ideal for outdoor environments, especially those exposed to oil, grease or other slippery solutions.



Outdoor metal stairs can be used for many purposes and are long-lasting. Lapeyre Stair offers an assortment of metal stairs including alternating tread, prefabricated metal and stair towers. These come in a variety of finish options including galvanized steel, powered coated steel and aluminum.


Lapeyre Stair also provides non-slip tread, diamond tread, bar grating and grip tread systems for our bolted, metal stair product line All of the tread systems above can be applied for our commercial steel stair product line.


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