By Michael F. Petersen, Petersen Aluminum Corporation
First, I believe it’s important to disclose that company name aside; we sell as much steel roofing material as we do aluminum. Both products feature specific attributes and all qualified commercial roofing contractors have the experience and expertise to install both.
So why isn’t aluminum used more extensively then? The primary obstacles have been cost per square foot and misimpressions concerning the structural limitations of aluminum. Recent innovations in panel design, though, have served to significantly broaden the application range for aluminum panels and several aluminum profiles are now available from a number of manufacturers that carry the UL 580 Class 90 wind uplift rating.
Despite recent inflation in steel costs, the initial installed cost of aluminum remains higher than steel, But that is not the end of the story. In many areas of the country, I would contend that a full analysis of life cycle benefits might actually show that aluminum is less expensive than steel. In my experience, building owners are increasingly deciding to use aluminum when they are fully informed of its advantages.
An intrinsic attribute of aluminum is its corrosion resistant properties – a significant advantage over steel. In the typical architectural application, G-90 galvanized steel or AZ 55 Galvalume steel are coated with a full Kynar 500 fluorocarbon finish. Either substrate provides adequate protection in a “normal” environment unless and until it is abraded. Surface scratches can cause the corrosion process to accelerate. This is particularly the case in acid rain regions, coastal areas and other aggressive environments. In such areas the advantage quickly switches to aluminum due to its superior corrosion resistance. Most manufacturers’ warranties I have seen specifically exclude corrosion of the substrate. Our experience over the past thirty years is that aluminum is the better substrate for those applications where substrate corrosion might be a concern.
But corrosion resistance isn’t the only reason aluminum is gaining popularity. The material is notably “designer friendly” and works well in fabricating even the most complex designs. Aluminum is easier to work with than steel and is generally available in a wider range of gauges than steel, thereby making it easier to co-ordinate fabrication of the various exterior metal components for your project. Aluminum features significantly lower weight per panel—in some cases a contractor might be able to use one installer versus two. It’s easier to cut and work in the field. This all adds up to labor cost savings.
Aluminum also scores well in sustainable design. A typical aluminum roof panel includes 90% recycled content and it is fully recyclable when necessary. Combined with a solar-reflective Energy-Star listed “Cool” coating, aluminum roofing is an excellent choice for a LEED qualified project.
We’ve had key architects tell us they prefer aluminum and use it every chance they get—particularly when they are working directly with building owners. They feel the additional cost of aluminum is inconsequential compared to the overall “value” enhancement of the project. In any assessment of overall life cycle and long-term maintenance costs, though, I believe the choice between steel and aluminum begins to even out. And if your project is based in an acid-rain environment or direct coastal area (or come to think of it, if you live in one of the Blue States!), you should strongly consider aluminum.