The focus is also shifting from first cost to long-term ownership cost. As landfills are overburdened with discarded building components, metal’s life-cycle economics, durability and environmental appeal offer compelling advantages, making it an increasingly popular roofing choice.

In non-residential construction, metal roofing has established a significant share across commercial, industrial and institutional buildings. The Metal Construction Association’s (MCA)[i] market study conducted by FMI Consulting indicates that metal’s share ranges from 24% to 35% in the commercial (24%), industrial (25%) and institutional (35%) building sectors. 

Residential market penetration of metal roofing has climbed from less than 2% to more than 13% over the last three decades, making it second only to asphalt shingles, suggesting that the overall market penetration of metal roofing is even greater.

Service Life & ROI

Metal roofs are known for durability, sustainability, varied styles and versatility, and are gaining popularity as maintenance and life-cycle ownership costs are substantially lower than the alternatives.

Commercial metal roofing is generally referenced as “low slope” or “steep slope.” Steep-slope roofs are generally water-shedding, or hydrokinetic, while low-slope roofs are water-tight, or hydrostatic, and suitable down to ¼:12 (2%) slopes—the same code-mandated minimum for single-ply.

A Metal Construction Association field-data/lab-analysis study indicates a service life of about 70 years for 55%AlZn-coated steel standing seam metal roofing (SSMR) in non-coastal applications. Steep-slope coated-steel roofing is expected to perform similarly, while stainless, copper and zinc can last well over a century, but these materials are often beyond the reach of many construction budgets.

That 70-year service life far exceeds non-metal commercial roofing systems, which generally expire around the 15–25-year mark. Over the life of a metal roof, an owner could otherwise face multiple roof replacements, along with the associated costs and disruption. Metal roofs also avoid much of the frequent, costly upkeep and repair.

Typical maintenance is minimal, involving annual gutter cleaning and debris removal, with inspection every three to five years or so. Semi-annual rinsing is often advised in coastal regions.

Increasingly, owners are choosing coated steel SSMRs over asphaltic and membrane roofs because a 20-30% initial premium is a bargain when SSMRs outlive those alternatives by three to four times.

Sustainability

Demand for durable, environmentally friendly materials with lower maintenance and longer service lives leads designers and owners to metal roofing. It is attractive, energy-efficient, weather-resistant and, relatively speaking, maintenance-free.

Metal roofing is a “green” and sustainable material because of its long service life, low consumption of natural resources, zero-petroleum by-products and recyclable economic prudence. Claims of “100% recyclability” are meaningless if recycling is not economically justified.

An old shoe, for instance, is 100% recyclable if you do not care about the cost of recycling versus its value once recycled. What matters is actual recycle rate. At a 98% recycling rate,² steel is the most recycled construction material available, second only to copper, and old metal roofs rarely end up in landfills.

Metal roofing is non-flammable, non-combustible and resistant to fire, weather and climate. Over open structural framing it is a Class A (UL 790) material with respect to burning-brand flame spread; over wood decking with special underlayment, it is also accepted by UL as Class A.

Modern SSMRs are designed to respond freely to thermal expansion and contraction. Metal is inert and impervious to UV degradation. Premium PVDF finishes offer up to 40-year warranties against excessive fade and chalk, and metal panels can be designed to resist virtually any wind speed, including Category 5 hurricane winds.

Reflective pigments used on metal roofs also rank among the highest in “cool roofing.” Oak Ridge National Laboratory studies report that metal retains reflectivity far better and longer than membrane materials that can lose up to 50% within three years.³ PVDF finishes also help dirt and pollutants wash away when it rains.

Why Choose a Standing Seam Metal Roof (SSMR)?

“Standing Seam” metal roofing has been used for more than a millennium on prestigious buildings including Notre Dame Cathedral, Westminster Abbey and historic buildings in our nation's capital.

SSMR attaches to the structure or deck with concealed clips folded into the standing seams. The clips allow panels to expand and contract freely with thermal cycling while keeping the weathering surface penetration-free. So how do you mount things without violating those two principles? This has been a perplexity for 1,000 years or longer.

Today's owners are faced with the need to mount essential rooftop equipment and ancillary mechanicals—HVAC equipment, screens to hide it, piping and conduit to fuel it, and walkways to access it. In years past, these ancillaries were often mounted in ways that violated roof integrity, compromising the exceptional lifespan of the metal roof.

Enter S-5! with disruptive innovations, beginning in 1992, that enable virtually anything to be attached to an SSMR penetration-free and without violating its thermal response—solving a 1,000-year-old dilemma. Mounting everything from a satellite dish to a PV solar array became easy, inexpensive and user-friendly.

Today's SSMR is a time-proven choice for both steep- and low-slope applications. Better yet, what was once a weakness is now an advantage: nearly anything can be mounted to this durable, sustainable roof without violating its integrity and service life. 

The Perfect Platform for Solar PV

Building owners are increasingly adding grid-tied solar photovoltaics (PV) to power their facilities. The financial prospectus makes sense—turning cash positive in the five- to seven-year range and providing power for decades thereafter.

As solar grows on commercial buildings, metal roofing has become a driver for roof-type selection. Costco, FedEx, Whole Foods and Walmart use solar, while Apple Inc.'s Silicon Valley campus includes a 7.4 MW roof-mounted array installed over an SSMR.

According to a Lawrence Berkeley National Laboratory study⁴, solar PV has a service life of 28 to 37 years, averaging 32.5 years. Most alternative roofing systems expire long before the PV system, requiring costly disassembly of the array, re-roofing and reassembly. An SSMR provides an ideal platform because it’s the only commercial roof type with a service life that exceeds that of the solar PV system.

Solar is also easier and less expensive to mount to metal than to other roof types, and in many cases the savings can offset the initial SSMR premium. PV can be mounted directly to the standing seams using tested and engineered mechanical attachments.

Contractors should understand roofing alternatives and service lives to add value for clients. When solar PV is incorporated into building design, the SSMR seems a no-brainer. Its service life, attachment advantages and long-term economics align naturally with solar. From both a financial and ecological perspective, it just makes sense.