Aside from catastrophic damage, metallic corrosion is clearly the chief cause of metal building panel failure. When architectural metal panels corrode, there are undesirable consequences that go beyond cosmetics. Corroding panel systems will begin to leak, causing potentially significant damage to the interior of a building. Repair costs can be substantial, usually involving removal and replacement.
Studies conducted in the 1990’s by both Battelle Laboratories and the National Association of Corrosion Engineers (NACE) concurred that in the United States alone, we spend nearly $300 billion per year combating metallic corrosion. The Battelle study estimated that $100 billion of this cost can be avoided with proper material selection. This suggests that to a significant degree, we are penny wise and pound foolish with the metals we specify. It has been estimated that half of new steel production relates to replacing corroded parts. Beyond the obvious economic impact, there is a negative environmental impact as well.
In terms of architectural metal applications, life cycle costing should be taken into account when selecting materials. It’s a simple case of measuring the cost of building materials that will last as long as the anticipated life of the structure and comparing those costs, in present value terms, to alternate materials that will require additional maintenance and/or replacement. Clearly, the construction industry has been operating in a mindset that maintenance and replacement of building materials is a foregone conclusion. However, in light of the extraordinary costs we bear in battling corrosion, more attention to material selection is warranted.
Since the corrosion cost studies of the 1990’s some progress has been made in addressing the problem. In order to stem corrosion costs that exceed $20 billion per year with the U.S. Armed Forces, a Corrosion Policy and Oversight office was established within the Pentagon in 2003. The Defense Department also contributed to the establishment of corrosion engineering program at the University of Akron. Clearly, the U.S. Government sees opportunity to reduce costs in the military budget.
There has been a great deal of growth in recent years in the use of metal building panels, which is a welcome step in the right direction. Metal panel systems are in a category above many conventional building materials in terms of long service life at a reasonable cost. However, greater consideration needs to be given to longer lasting metals like stainless steel, zinc and copper for cladding applications on buildings with anticipated service lives that exceed 50 years. This is particularly true in coastal locations and climates where deicing salts are used. Corrosion failures of conventional metals are more prevalent in these locations due to chloride exposure. While paint systems go a long way to preserve substrate metals like carbon steel and aluminum, sheared edges and areas compromised by damage, metal forming and welding go unprotected. Provided the right grade of stainless steel is matched with the environment, as an example, corrosion is not an issue.
The construction industry has seen measurable growth in the use of more corrosion resistant metals. Just 10 years ago, a stainless steel building envelope was considered to be extravagant; reserved only for iconic buildings with exceptional budgets. Today, however, stainless steel and other corrosion resistant metals have gained acceptance for use on projects in the mainstream. What was once thought to be extravagant is now considered to have solid economic value. A stainless steel finish needs only to be cleaned periodically to last as long as the building stands. With no repainting or replacement required, the building owner gets a solid return on investment. Further, service disruptions and their related costs are avoided.
Beyond the simple math of maintenance savings from using durable materials like stainless steel, building owners get the added benefit of higher property value. While it may be difficult to put a precise value on a building with a stainless steel envelope compared to one that requires refinishing or replacement, it stands to reason that the owner has a valuable selling point when the time comes to sell. It’s similar to the residual value argument that car rental and leasing companies embraced years ago. In the old days, fleet cars were stripped down, entry level models that provided low cost transportation. In contrast, today’s fleets are more likely to include better models with higher value features that support better residual value when the vehicle is resold. Similarly, building owners should take note of residual value as they, their architects and contractors make decisions regarding construction materials.