Copper-clad Stainless Steel Replaces a Tornado-damaged Roof at the St. Louis Airport

Hundreds of people milled about the terminals at Lambert-St. Louis International Airport on the evening of April 22, 2011. Three airplanes with passengers on board sat on the tarmac. It was business as usual at one of the largest municipal airports in the country. But meteorological conditions were anything but usual. A powerful supercell over St. Louis spawned an EF4 tornado (view the Enhanced Fujita Scale, which rates the strength of tornados by the damage caused, on page 2) packing 150-mph winds. The twister barreled directly into the airport 11 miles northwest of downtown, blowing out half the floor-to-ceiling windows in the main terminal and inflicting approximately $30 million in damages. In addition, the tornado seriously damaged part of the copper roof over Terminal 1.

CopperPlus was installed in stages over the domes at Lambert-St. Louis International Airport. Like solid copper, copper-clad stainless steel acquires a patina over time.

CopperPlus was installed in stages over the domes at Lambert-St. Louis International Airport. Like solid copper, copper-clad stainless steel acquires a patina over time.

The 55-year-old roof was iconic and beautiful. Its four copper domes had been the crowning glory of Lambert-St. Louis International Airport, welcoming up to 13 million international passengers each year. But the roof had been showing its age for some time, leaking often and requiring frequent maintenance. Following the tornado strike, airport officials made the difficult decision to permanently retire the roof. “The tornado damaged less than 10 percent of the total roof, but that section needed to be totally replaced,” explains Jerry Beckmann, deputy airport director of Planning & Development. “That damage, plus the fact that the roof was almost 60-years old, influenced our decision.”

Airport officials were challenged to install more than 100,000 square feet of material over four domed vaults as quickly as possible with minimal disruption to the public. Beckmann, who is an engineer, wanted a roof that was watertight and capable of withstanding high winds while airport administrators wanted to maintain the roof’s mid-century architectural integrity. All parties wanted the project completed as economically as possible with results that were aesthetically pleasing, historically appropriate and, most important, built for harsh weather events.

COPPER AND STEEL

They found the solution in copper-clad stainless steel, a material that has been used in roofing applications for roughly 50 years. The selected ASTM B506-09 architectural metal features two outer layers of 100 percent copper strip roll bonded at very high pressures to a core of Type 430 stainless steel, the same metallurgical bonding process used to make U.S. quarters and dimes. The material delivered the natural beauty and patination properties of solid copper with the strength and durability of stainless steel—exactly the attributes desired by officials at Lambert-St. Louis International Airport.

“Copper-clad stainless steel is a great-looking material that can be fabricated for any roofing style. You can’t tell the difference between it and straight-up copper,” says Shane Williams, vice president of Civil Construction for Kozeny-Wagner Inc., the Arnold, Mo.-based general contractor awarded the public bid by the city of St. Louis. “It’s stronger, has a better shelf life and costs less than pure copper. This allowed us to bid competitively for the job and even return a credit to the city of St. Louis.”

Workers install CopperPlus batten-seam panels over a dome at Lambert-St. Louis International Airport. Stepby- step, the installation of CopperPlus is virtually identical to that of copper.

Workers install CopperPlus batten-seam panels over a dome at Lambert-St. Louis International Airport. Step-by-step, the installation of CopperPlus is virtually identical to that of copper.

The owners of Missouri Builders Service Inc., the Jefferson, Mo.-based roofing subcontractor, were attracted to the material’s lighter weight and easy solderability. “We were going to have to maneuver a lot of material on the job site and perform a very large amount of soldering to cover four domes,” notes John Kinkade, Missouri Builders Service’s vice president. “We liked that copper-clad stainless steel had a lower thermal conductivity for easier soldering. That was important to us, given the scope of the project.”

The $6.7 million project to replace the airport roof was announced at a press conference in March 2014 by St. Louis Mayor Francis Slay, St. Louis County Executive Charlie Dooley and Lambert-St. Louis International Airport Director Rhonda Hamm-Niebruegge. “The new skin will shine of raw copper like it did in the mid ’50s when the terminal was built,” Slay stated in a press release issued by the airport. “The roof will slowly transform in color again in time as this airport serves new generations in this region.”

WEATHERING NATURE’S WORST

Copper-clad stainless steel has become more popular in tornado and hurricane-prone regions of the U.S. in recent years, thanks to the strengthening of building codes for wind-lift and hail-resistance standards. Copper-clad stainless steel conforms to Miami-Dade BCCO requirements and exceeds UL2218 Class 4 hail-test requirements; wind-uplift tests have shown its strength to be equivalent to steel at the same gauge. It offers a strength advantage compared to solid copper, providing higher tensile strength and yield strength at a thinner gauge than monolithic copper.

Numerous churches, college buildings, museums, private residences and other buildings nationwide now feature copper-clad stainless steel in their custom roofs, dormers, cupolas, flashings and downspouts. Notable installations include the following:

  • Several 67-foot panels of copper-clad stainless steel were rolled onsite, then lifted and put in place by a crane to replace the ice-damaged roof at the St. Francis of Assisi Catholic Church, Traverse City, Mich.
  • In 2012, more than 30,000 square feet of copper-clad stainless steel were installed in the fascia and coping of the Trinka Davis Veterans Village, Carrollton, Ga., the nation’s first privately funded U.S. Department of Veterans Affairs’ VA facility.
  • In 2014, the material was selected for a 2,100-square-foot perforated sunscreen installation in San Francisco’s Mission Bay neighborhood, one of the most significant urban development projects in the U.S.

PHOTOS: MISSOURI BUILDERS SERVICE INC. AND LAMBERT-ST. LOUIS INTERNATIONAL AIRPORT

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Metal Roofing Resembles Shake, Slate and More

Quality Edge has launched Matterhorn Metal Roofing, which is made from steel and available in four profiles: Shake, Slate, Tile and Standing Seam.

Quality Edge has launched Matterhorn Metal Roofing, which is made from steel and available in four profiles: Shake, Slate, Tile and Standing Seam.

Quality Edge has launched Matterhorn Metal Roofing, which is made from steel and available in four profiles: Shake, Slate, Tile and Standing Seam. A two-year development process resulted in carefully crafted splits, cracks and grains that mimic each profile’s natural counterpart. The shake profile features 21 individual shake designs to enhance the natural overall effect. In addition, Matterhorn’s patented fourpoint fastening system conceals the overlapping metal panels on slate and shake. All profiles have been tested to withstand hurricane-force winds up to 130 mph.

Steelscape Now Offers Graffiti-resistant Coatings from PPG

PPG Industries’ building products group announced Steelscape is now offering metallic-coated and pre-painted steel with DURANAR GR (graffiti-resistant) and CORAFLON GR coatings.

Duranar GR and Coraflon GR three-coat systems feature a primer and color coat topped with a graffiti-resistant clearcoat that can be cleaned with DURAPREP Prep 400 graffiti remover by PPG. If the Steelscape steel is spray-painted, graffiti can be eliminated by applying the graffiti remover directly to the stain, allowing it to sit for 10 to 60 seconds, then wiping it with a clean cloth or scrubbing it with a nylon brush. Most stains can be removed in 10 minutes or less.

When applied on either Duranar GR or Coraflon GR clear coatings, Duraprep Prep 400 field-applied graffiti remover also can eradicate paint overspray, pen and marker ink, lipstick, scuff marks, tape residue, bugs, tar and many other substances that mar the appearance of steel building panels.

Duranar GR coatings are available in a variety of low and medium glosses; Coraflon GR coatings are for high-gloss finishes.

Roofing Manufacturers and Contractors Embrace Recycling

In the early 2000s, as the green-building movement reached its tipping point, the roofing industry’s contributions to sustainability focused on increasing energy efficiency, improving long-term durability and addressing the heat-island effect. In the years since, significant strides have been made in all three of these areas for commercial and residential buildings.

In recent years, increasing attention has been given to the benefits and challenges of recycling roofing materials at the end of their useful life. This is no trivial task: Owens Corning estimates asphalt shingles alone comprise up to 5 percent of building-related landfill waste. This doesn’t take into account other roofing materials, including EPDM, thermoplastic PVC and metal.

Not surprisingly, rising removal costs, coupled with the growing demand in some areas of the country to legislate landfill content, are putting pressure on contractors and building owners to seek alternatives to traditional roof construction scrap and tear-off disposal methods.

In response, greater numbers of roofing manufacturers and contractors are driving strategies to avoid the landfill. A general review of emerging trends across the roofing industry suggests manufacturers and contractors increasingly are turning to recycling to steer these materials from the waste stream.

Steel is the most recycled material in building construction today. PHOTO: STEEL RECYCLING INSTITUTE

Steel is the most recycled material in building construction today. PHOTO: STEEL RECYCLING INSTITUTE

METAL

Metal roofing’s sustainable attributes are significant. Industry experts cite its ability to improve a building’s energy efficiency, and metal today contains anywhere from 25 to 95 percent recycled material.

On its website, the Chicago-based Metal Construction Association (MCA) encourages installing metal roofing directly over an existing roof, thus eliminating the need to dispose of the original materials. But when an older metal roof or new-construction debris must be removed from a site, contractors and owners in most regions of the country can quickly identify scrap yards that take metal.

“Steel is the most recycled material in building construction today,” says MCA Technical Director Scott Kriner. “There’s an infrastructure that supports it, and metal in general is virtually 100 percent recyclable.” Kriner notes MCA supports recycling as part of the metal industry’s overall commitment to environmental sustainability and transparency in business.

PVC

PVC has been used in roofing systems since the 1960s, and the post-consumer recycling of roof membranes began in North America in 1999—a nice symmetry when one considers roofs in terms of 30-year life cycles.

In general terms, the recycling of PVC roofing is a relatively straightforward process. The material is sliced into long strips, rolled up, lifted off the roof and transported to a recycling center. Recyclers run the PVC through a conveyor system, where fasteners and other metal objects are removed.

Initially, the recovered membrane was ground into powder for reuse in molded roof walkway pads. More recently, some manufacturers have been incorporating a granulated form into new PVC roofing membranes, exclusively on the backside to avoid aesthetic issues with color variations. The first installations of membrane produced with post-consumer recycled composition occurred in the mid-1990s. So far, its field performance has matched that of PVC roofing produced with virgin raw materials.

The Vinyl Institute, Alexandria, Va., says close to 1 billion pounds of vinyl are recycled at the postindustrial level yearly. “The vinyl industry has a history of supporting recycling,” the institute reports on its website, “and this effort continues as companies, alone and through their trade associations, expand existing programs and explore new opportunities to recover vinyl products at the end of their useful life.”

EPDM

Ethylene propylene diene terpolymer is used extensively on low-slope commercial buildings. Yet even this durable synthetic rubber membrane must eventually be replaced, and today recycling is a viable option.

The removal process generally involves power-vacuuming off the stone ballast, where present, to expose the EPDM membrane below. The membrane can then be cut into manageable squares, which are folded and stacked on pallets, loaded onto a truck and transported for recycling. The recycler grinds it into crumbs or powder, depending on the end use. A growing number of recycling centers nationwide now handles EPDM.

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Roof Decks: Don’t Underestimate the Backbone of the Roof System

NOTE: This article is intended to provide general information while conveying the importance of the roof deck as an integral part of a roof system. Additional information about specific effects and concerns in regard to roofing can be found in The NRCA Roofing and Waterproofing Manual and various roof-cover manufacturers’ design guides.

Wood plank decks can provide a dramatic exposed roof deck.

Wood plank decks can provide a dramatic exposed roof deck.

The roof deck is the backbone and an integral component of all roofing systems. Its main function is to provide structural support for the roof system and, therefore, is a building element that needs to be designed by a licensed design professional because proper support of the roofing above is critical to the roof system’s success.

Roof decks also add thermal performance and fire resistance and ratings, provide slope for drainage and enhance wind-uplift performance. They must accommodate building movement and often determine the attachment method of the vapor retarder, insulation and membrane.

Roof Deck Types

There are many types of roof decks being installed today:

  • Steel
  • Precast concrete panel
  • Structural concrete
  • Cementitious wood fiber
  • Wood planking
  • Plywood/OSB
  • Poured gypsum

Some decks are covered with topping fills that become the base for the roof system and may also be an integral structural component:

  • Concrete
  • Lightweight insulation concrete topping
  • Lightweight aggregate concrete topping

Other deck toppings are available, such as poured gypsum and lightweight concrete with integral insulation, but these are considered substrate covers and not roof decks.

The most prevalent roof deck in the U.S. for commercial buildings is steel. On the West Coast, plywood/OSB is very popular. In addition to the roof decks already mentioned, in the course of roof-replacement work the designer may come in contact with the following:

While the “plate” test is not a preferred method, it can quickly and inexpensively give an indication of retained moisture in lightweight aggregate concrete roof deck covers.

While the “plate” test is not a preferred method, it can quickly and inexpensively
give an indication of retained moisture in lightweight aggregate
concrete roof deck covers.

  • Book tile
  • Lightweight precast concrete planks
  • Precast gypsum planks
  • Transite

Collaboration with the Structural Engineer

Because a roof deck is the foundation for the roof system, the designer needs to coordinate the roof system design requirements for the roof deck with the structural engineer to ensure the performance of the roof system. For example, the roof deck may need to extend to the roof edge. In this example, the roof deck may not need to extend to the roof edge for structural concerns but is needed to support the roof system; the roof designer must address this. If the roof deck is structurally sloped, the designer and engineer must determine whether the low point is a potential drain location. Are there steel beams in the way of the drain location? The roof deck must be attached to the structure to prevent uplift. And the designer and engineer must determine what the deflection of the roof-deck span may be between structural supports. For example, steel deck is sometimes installed with spans of 7 feet between joists and flexes (deflects) under foot traffic. This typically is not a good condition onto which a ridged roof system, such as a bituminous one, should be installed. It cannot be expected to accommodate such deflection. PHOTOS: Hutchinson Design Group Ltd. [Read more…]

Replacement Solution Includes Framing, Sub-framing and Metal Roof Panels

Metal Sales Manufacturing Corp.’s Retro-Master roof replacement solution

Metal Sales Manufacturing Corp.’s Retro-Master roof replacement solution

Metal Sales Manufacturing Corp.’s Retro-Master roof replacement solution includes structural framing, sub-framing and metal roof panels. The 100 percent steel system can be installed over any existing sloped or flat roof whether metal, asphalt, built-up or membrane. Insulation can be added to the roof system, and a variety of cool-roof-compliant colors are available. The system also accommodates photovoltaic integration and rainwater catchment.

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