Strategic material selection to prevent corrosion in building structures

Corrosion is precipitated by environmental factors like humidity, air salinity, and chemical content. However, the use of certain materials can limit or completely negate damage introduced from these conditions.
Iron and steel are ubiquitous components in nearly all construction jobs. However, some alloy steels have limited corrosive resistance due to their high carbon content. Selecting a steel alloy with low carbon content, such as 300 series stainless steel, can diminish the chances of corrosive damage. Note, however, that as the corrosive resistance of a material is improved, its structural strength characteristics decrease and its cost tends to increase.
To decrease cost but improve performance in harsh environments, a number of different coatings can be applied to (typically steel) building components to prevent corrosion. One method, called galvanizing, applies a thin layer of zinc or magnesium to steel components. This coating will sacrifice itself to protect the structural integrity of the base component. See the below table for a general guideline on selecting materials and coatings based on specific jobsite conditions.
While this sacrificial property of metals can be exploited to extend the lifetime of certain parts, it can also work adversely if not considered when dissimilar metals are in contact. Known as galvanic or bimetallic corrosion, dissimilar metals, when in contact with each other and an electrolyte like water, will cause one material to rust faster than the other. Most commonly, this type of damage is seen when steel and copper are in contact on the exterior of a building, but many other combinations can also cause corrosion. The chart below can be utilized to determine which metals can safely be used in conjunction.

Building methods to prevent corrosion

For over 80 years, architects have leveraged rainscreen concepts to extend the lifespan of exterior components on buildings. This method relies on the use of an exterior frame to act as the building's outermost shell. The shell will make direct contact with rain, wind, and corrosive exterior conditions to shield the inner walls from corrosive damage. More sophisticated rainscreens balance air pressure between the interior building and exterior frame to prevent condensation from forming on the inner structure. Certain building codes will require the use of a rainscreen, and the designer should consider this during the planning process.
To learn more about how rainscreens can protect buildings from corrosive damage, we welcome you to explore Nvelope systems and products.

Rust-Proof top coats

Many components can also be specified with a rust-preventative top coat. These come in a myriad of types with varying properties. Epoxy coatings provide good strength but are susceptible to color fading. Alkyd enamels have comparable strength but are less susceptible to color damage from UV rays. Polyurethane coatings typically have the best strength characteristics and UV resistance.
As coating effectiveness improves, cost also tends to increase. A designer should consider how much corrosion resistance is required, and ensure that the top coat color matches other building components.

Warranty inquiries

Some component manufacturers specify warranties on their parts regarding corrosive resistance. It's typically a good idea to ask suppliers about potential warranties, as this is a good indicator of both product performance and supplier confidence.

Determine the appropriate level of rust prevention with insights from SFS

Consult with the product managers and engineers of SFS about which fastening and rainscreen solutions provide the necessary protection from corrosion. We can recommend solutions which account for the intended part utility, budgetary restraints, and environment

ERICH BIO PLACEHOLDER