Butterfly Roof and Metal Wall Panels Highlight New Multipurpose Facility

Sevier County Utility District’s new multipurpose facility sports a butterfly roof over the main event space and two lower roof sections that cover offices, conference rooms and the kitchen. Each end of the building is open, with overhanging roofs, allowing for mountain views. Photo: Denise Retallack

The centerpiece of Sevier County Utility District’s new multipurpose facility in in Sevierville, Tennessee is a large event space that can be used by the district or rented to the public. The building also houses large conference rooms, a training room, a fitness area, administrative offices and a catering kitchen.

The design features large clerestory windows that flood the interior with natural light and a front canopy supported by steel columns. The facility’s exterior is dominated by its striking, V-shaped standing seam metal roof and metal wall panels, which are accented by brick and fiber cement siding.

“The roof was a major design element on this project from the beginning,” says A.J. Heidel, project manager for BarberMcMurry Architects in Knoxville, Tennessee. “We used the blue butterfly roof to accent the main assembly space and we used the lower roof as a wrapping element for the support spaces.”

To execute the design, it took a talented group of construction professionals including two Knoxville-based companies: Denark Construction, the general contractor on the project, and Baird and Wilson Sheetmetal Inc., the roof and wall system installer.

Crews from Baird and Wilson Sheetmetal installed approximately 13,500 square feet of Petersen’s PAC-CLAD Tite-Loc panels in Berkshire Blue on the roof. Photo: Denise Retallack

BarberMcMurry, Denark Construction, and Baird and Wilson had teamed up on other projects for the Sevier County Utility District (SCUD) in the past, so they were a perfect fit for this new construction project. The roof system chosen for the building is comprised of Petersen’s PAC-CLAD Tite-Loc panels in Berkshire Blue.

“We chose a standing seam metal roof because its material properties allow for a range of colors and ribbing patterns, and because of its ability to act as a wall cladding as well as roof,” notes Heidel. “We were able to give different characteristics to separate volumes by changing from blue smooth flat lock panels to Musket Gray ribbed panels while maintaining a similar method of installation.”

The design team originally explored using insulated metal panels for the roof and walls. “We were asked by Denark Construction to price this project,” says Jim Galbraith, vice president of Baird and Wilson. “I priced the insulated roof and wall panels and Denark came back asking if there were potential savings through value engineering. We submitted pricing for single-skin roof and wall panels and it was accepted.”

To make sure everyone was on the same page, pre-construction meetings involving the architect, general contractor and roof system installer included a mock-up of the panel system. “We had a mock wall with all of the roofing and wall conditions, and we met with them on site to go over all of the details,” explains Heidel.

The Installation

Baird and Wilson installed approximately 13,500 square feet of Tite-Loc roof panels on the roof, as well as 3,500 square feet of 16-inch Snap-Clad standing seam wall panels. “We also fabricated and installed gutter, downspouts, horizontal flush wall panels, low and high soffit, and fascia,” notes Galbraith.

After the metal deck topped with a nail base, insulation, and ice and water shield, the roof panels were installed and mechanically seamed. “The slope was less than 3:12, so the Tite-Loc panel was a perfect fit,” Galbraith says.

The exterior of the is features a mix of materials, including seamed metal wall panels, flush wall panels, fiber cement siding and brick accents. Photo: Matt Horton, hortonphotoinc.com

Work began on the butterfly roof. The valley features an internal gutter, which drains through downspouts that penetrate through the soffit and go down the front of the building, where they drain through underground pipes. “At the entrance we installed some horizontal blue flush panels that matched the roof,” notes Galbraith. “We also installed the fascia and soffit in Berkshire Blue, which matched the roofs on other buildings on the campus, which were also that color.”

The roof-to-wall transition was designed to make it appear the roof was wrapping around the building. “The roof panels were 16 inches on center, and the wall panels were 16 inches on center,” Galbraith explains. “The seams on the wall panels and the roof panels had to line up perfectly all the way down, so that was a bit tricky. You had to pay attention and do the math as you were going down to make it all work.”

Challenging Site

The limited area surrounding the building proved to be a major challenge on the project. “The building itself takes up much of the buildable area, leaving little room for things like parking and site drainage,” says Heidel. “We were able to avoid a water detention pond by using rain gardens on the site.”

The rain gardens are located against the main road, with parking spaces designed to shed water to that area, which includes native plants that thrive in a wet habitat. The pipes from the building’s downspouts flow there as well.

Tennessee’s spring weather was also a concern. “Construction took place in early spring, and the wind was whipping,” says Galbraith. “It was also rainy, and there was a corner where water would sit, so we had to be careful moving our lifts so they didn’t get stuck in the mud. The most difficult problem was manhandling the long roof panels. Many were more than 50 feet long.”

Photo: Matt Horton, hortonphotoinc.com

Despite the challenges, the project went smoothly. “BarberMcMurry prioritizes long-term client relationships, and this project is a great example of that,” Heidel says. “We have a history of successful projects with SCUD, and we continued that pattern through this project, which was delivered on time and on budget.”

“We work with our clients on designs that fit their brand, reflect their use, and are fully functional as well as beautiful,” Heidel continues. “That outlook is reflected in this project, too, through the overall design of the spaces and our creative use of materials. Finally, BMA is committed to sustainability and stewardship through design. In this project with SCUD, you can see sustainable design elements in the rain gardens, which filter and control the release of storm water as it leaves the site, and in the building’s clerestory windows and shaded curtain wall, which take advantage of daylighting.”

The project also showcases the quality workmanship of Baird and Wilson. Galbraith cited a quote from Charles R. Swindoll that serves as a company motto: “The difference between something good and something great is attention to detail.”

TEAM

Architect: BarberMcMurry Architects, Knoxville, Tennessee, www.bma1915.com

General Contractor: Denark Construction, Knoxville, Tennessee, www.denark.com

Roofing Contractor: Baird and Wilson Sheetmetal Inc., Knoxville, Tennessee, www.bairdandwilson.com

MATERIALS

Roof Panels: PAC-CLAD 24-gaugeTite-Loc panels in Berkshire Blue, Petersen, www.PAC-CLAD.com

Wall Panels: PAC-CLAD 24-gaugeSnap-Clad panels in Musket Gray

New Synthetic Slate Roof Tops Historic Owatonna City Hall

The city offices in Owatonna, Minnesota, are housed in a historic building that underwent a complete roof replacement as part of an ambitious restoration plan. Photo: Lakeshore Drone Services

The massive brick complex in Owatonna, Minnesota, that currently serves as its city hall has an interesting past. According to Aaron Fitzloff, facility manager for the City of Owatonna, the structure was originally built in 1886 as the Minnesota Public School for Dependent and Neglected Children. The facility closed in 1945 and later became the Owatonna State School. “The state closed it in 1970, and the city of Owatonna took it over in 1974,” notes Fitzloff. “In 1975, the building was listed on the National Register of Historic Places.”

The complex now houses administrative offices for the city and the Minnesota State Public School Orphanage Museum. Asphalt shingles had been installed on the roof at some point in the 1990s, but leaks developed over the years, and the city budgeted for a complete roof replacement as part of an ambitious restoration plan. “The intent was to get the building back to its original state,” says Fitzloff.

Specifying a New Roof

The city consulted with Adsit Architecture and Planning, a full service architectural and interior design firm located in Minneapolis. When the firm completed a condition assessment for another historic building in Owatonna— the Firemen’s Hall —that project led to a request from Fitzloff to look at the city’s administration building.

Crews from Schwickert’s Tecta America installed more than 29,000 square feet of DaVinci synthetic slate. Photo: Lakeshore Drone Services

“Aaron realized that all of the roof systems were in need of replacement at this point,” says Gunstad. “He wanted to make sure, first and foremost, that we mitigated any moisture problems that were occurring up in the attic space. The project was about insulation as well as roofing.”

Finding the right roof system was crucial. Evidence suggested that the original roof was comprised of slate, but that couldn’t be confirmed due to a fire that had destroyed the main building in 1904. “Even before we did our research, we knew from our first look at the building that an asphalt roof on a building of this mass and scale did not look right,” Gunstad says.

Adsit Architecture specified a synthetic slate roof system manufactured by DaVinci Roofscapes. “Right off the bat we felt that given the scale of the building that slate would have been prohibitively expensive for them, and they agreed,” Gunstad recalls. “We knew with the cost, ease of installation, the warranty, the weight — all of that — the synthetic slate would be a really good fit, and DaVinci had an enormous amount of color choices for the blends we needed.”

DaVinci’s Color Visualizer Tool was used to help determine the colors. A European blend of gray shades and purple was installed. As the project got under way, the hunch that the original roof was slate was confirmed. “When we got into reconstruction and were up digging around in the attic, we did find some old slate pieces,” Gunstad recalls. “Oddly enough, they were a perfect match for the colors we had chosen.”

Installing the Roof Systems

The installer on the project was Schwickert’s Tecta America, headquartered in Mankato, Minnesota. “We ended up being the only bidder on it, which of course you don’t know at the time,” notes Scott Haefner, Schwickert’s steep slope project manager.

The scope of work on the project included 60-mil Carlisle EPDM, new gutters and custom-fabricated metal trim. Photo: DaVinci Roofscapes

According to Haefner, the difficulty of the project is what made it appealing for the company, which thrives on projects others turn away from. “Those are the ones we look for — the ones that have some complexity to it,” says Haefner. “That’s where we can shine. We have our own metal shop, we can do all our own metal fabrication, and we can do the types of things that can really set us apart. It gives us an advantage because we don’t have to farm some of that work out, and we have complete control over the whole process.”

The scope of work included installing more than 29,000 square feet of the DaVinci synthetic slate. The roof also included low-slope areas, and for these a 60-mil EPDM from Carlisle was installed. Sheet metal work included new gutters and custom-fabricated metal trim.

The safety plan was crucial, as the building would be open during the construction process. “You start with the safety plan,” says Haefner. “With staff and members of the public walking in and out, it is critically important in your pre-construction meetings to address those issues with overhead protection in certain areas, and blocking off certain areas when you’re working above them for the day.”

The safety plan incorporated scaffolding and personal fall arrest systems, as well as overhead protection for pedestrians. Photo: Schwickert’s Tecta America

Coordination with the city staff was critical. “Aaron Fitzloff helped us tremendously in that area,” says Haefner. “We had a standing meeting every Tuesday morning at 9, and that was always a big part of the conversation — safety and the sequence of what we were going to do that day. Aaron and I would also see each other every day also, typically. He was a great attribute to the whole project, for sure.”

Safety equipment included scaffolding and PFAS. “The vast majority of the building was scaffolded,” Haener says. “Fall arrest was anchored to the roof in areas we didn’t have scaffolding, and even where we did, the roof pitch was steep enough that everyone was always tied off with anchors and fall arrest systems.”

Work began in the late fall and progressed in sections. “That’s part of the beauty and charm of the building — its different additions and roof sections,” notes Haefner. “That also allowed us to focus on one area at a time. That’s typically what you do — you start and do a section that’s kind of an easy one to just get your feet underneath you and get a feel for how it’s going to go. There were some big, long planes of roof that we were able to get a start on and get a feel for the whole sequence.”

Schwickert’s steep-slope division handled the composite slate roof installation, while its flat roof division tackled the EPDM roofs.

Tying in flat and steep-slope roof systems was critical. Steep slope-crews completed most of their work first, using a Grace Ice & Water Shield product that is compatible with EPDM. “Let’s say you know the EPDM is going to go let’s say two feet up the slope of the roof, from flat to transition up the steep slope,” Haefner explains. “We’d leave off the bottom two or four courses of shingles, and leave the ice and water shield exposed, but not adhered.”

Photo: DaVinci Roofscapes

Low-slope crew members would just flip up the ice and water shield and install the EPDM. Steep-slope crews would then install the metal flashing, adhere the ice and water shield, and add the final courses of shingles.

A snow retention system from Rocky Mountain Snow Guards was installed in several sections of the roof.

Re-roofing the large turret was made easier by DaVinci’s turret package, which supplies pre-cut tiles. “You give them some basic information, including the circumference and the pitch,” Haefner says.

It worked well on the project, with one minor hitch that was quickly remedied. “This one was a little different because it has a sort of witch’s hat appearance to it, where the pitch changes at the bottom,” Haefner says. “It’s not a typical cone shape. When I sent in the request for the package, I didn’t take that into account, and we needed to order some more shingles to finish the turret.”

The large finial on the turret was taken down, painted and replaced.

A heat mesh system was installed in certain areas that had been subject to ice dams in the past. The Warmquest Zmesh system consists of woven copper mesh, which was installed below the tile, sandwiched between layers of ice and water shield. “That was a tricky part of the installation,” says Haefner. “We had to run big transformers, electrical panels, and run conduit to these areas from the old attic.”

The Minnesota weather brought things to a halt in the mid-winter, and work concluded this spring.

Mission Accomplished

Haefner points to this project as proof of his company’s ability to complete projects with multiple scopes of work. “With steep slope, flat roof, sheet metal work, new gutters, insulation, and the electrical portion involved with installing the heat mesh system — it shows perfectly how we can install multiple complex systems that have to go together in a certain way,” he says. “That type of complexity is where we shine.”

The city and its residents have been pleased with the result, according to Fitzloff. “Feedback has been nothing but positive,” he says. “We cleaned all of the limestone around the whole building as well, and it looks fabulous.”

Gunstad notes that the project fulfilled its design goals: making the building sound and restoring it to its former glory. “Performance and maintenance of the project were our primary concerns, but design-wise, looking at this building, which is rather grand, we knew it lacked something — and that something was a substantial roof,” says Gunstad. “We wanted to give that visual prominence back to that building, which is a hallmark of the city.”

TEAM

Architect: Adsit Architecture and Planning, Minneapolis, Minnesota, www.adsitap.com

Roofing Contractor: Schwickert’s Tecta America, Mankato, Minnesota, www.schwickerts.com

MATERIALS

Synthetic Slate: Single-Width Slate, DaVinci Roofscapes, www.davinciroofscapes.com

Low-Slope Roof: Carlisle 60-mil EPDM

Leak Barrier: Grace Ice & Water Shield

Underlayment: Titanium UDL

Snow Retention: Rocky Mountain Snow Guards

Community Center Sparkles With New Metal Roof

The community center was re-roofed using a structural sub-framing system from Roof Hugger that allowed the existing metal roofing to remain in place while the new roof system was installed above it. Photos: Roof Hugger, LLC

Just down the road from Pigeon Forge, Gallatin, Dollywood and other popular attractions in the Smokie Mountains is the thriving community of Sevierville, Tennessee. This beautiful mountain town has a community center and a civic center that hosts multiple events throughout the year. The community center is housed in a 1985 vintage metal building manufactured by American Buildings. Due to its age, the building recently underwent a complete re-roofing with metal in a process commonly known as a metal-over-metal retrofit. The building was originally constructed using American’s trapezoidal standing seam profile, so the decision was made to utilize a structural sub-framing system furnished by Roof Hugger, LLC. This type of retrofit allows the existing metal roofing to remain in place. The structural sub-framing is installed over the existing roof and then a new metal roof system is installed, which becomes the finished weathering surface.

The local community leaders were not new to this type of re-roofing for aged metal roofs because of their experience with a 2017 project at Lanier Elementary School in nearby Maryville. This project was designed by Chuck Howard of Metal Roof Consultants (MRC) from Cary, North Carolina, the same company selected for the community center re-roof. MRC has years of experience with retrofit roofing of existing metal roofs, as well flat roofs that receive an engineered light-gauge steel framing system to create a sloped roof plane. On the community center project, MRC consulted with Doyle E. Jones of Sevierville, the architect and roof consultant on the Lanier Elementary project.

Morristown Roofing was awarded the community center project through a public bid process in early 2019. Founded in 1962 by the late Paul Horner, Morristown Roofing now has a footprint of quality roofs in six states throughout the Southeast. With an overall staff of about 55 employees, the company installs all types of roofing from single-ply membranes to metal. The company’s motto: “No project is too large, nor too small for Morristown Roofing.”

According to Ashley Horner of Morristown Roofing, this project was only the company’s second Roof Hugger installation. The job went smoothly, even with the building’s roof geometry having had sloped rakes, varying slopes, multiple valleys and other difficult transitions. Horner went on to say the Roof Hugger product has the ability to increase snow loading and has little to no impact on the occupants of the building. It also helps control the contractor’s liability by eliminating the need to remove the existing metal roof. In addition, with existing trapezoidal metal roofs that are notorious for varying center-to-center major rib spacing, the Roof Hugger sub-purlin design compensates for this issue. Factory oversize notching of the Z-shaped sub-purlin’s vertical web permits easy installation directly over the existing roof panel high ribs, allowing for base flange attachment into the existing purlins. The result is a structurally correct, low-profile, finished retrofit framing assembly ready to receive the new metal roof panels.

The project finished out with 54,000 square feet of 24-gauge  System 2500 metal roofing by MRS Metal Roofing Systems, Inc. Approximately 12,720 linear feet of Roof Hugger’s standard Model “D” sub-purlin with a 4.5-inch web height was installed. The new roof included a ColorGard snow retention system manufactured by S-5!

TEAM

Consultant: Metal Roof Consultants (MRC), Cary, North Carolina, www.metalroofconsultants.net

Roofing Contractor: Morristown Roofing, Whitesburg, Tennessee, www.morristownroofing.net

MATERIALS

Structural Sub-Framing: Roof Hugger, LLC, www.roofhugger.com

Metal Roof: System 2500, MRS Metal Roofing Systems Inc.,  www.metalroofingsystems.biz

Snow Retention: ColorGard, S-5!, www.S-5.com

Re-Roof of Busy Post Office Facility Becomes Award-Winning Project

Crews from Roofing Solutions replaced the 300,000-square-foot roof on the United States Post Office General Mail Facility in Baton Rouge, Louisiana. Photos: Sam Barnes

The United States Post Office General Mail Facility in Baton Rouge, Louisiana, manages mail for the entire Greater Baton Rouge area. When the roof on the 300,000-square-foot building was nearing the end of its useful life, it was clear the roof replacement project would pose some big challenges. It was a given that the new roof system must prove durable and reliable to protect the mail delivery system that businesses and individuals rely on every day. It was also critical that the re-roofing work would not interfere with mail processing at the facility, which operates around the clock.

Architect Crump Wilson and Wharry Engineering specified an asphalt roofing system for the project — a two-ply modified bitumen system manufactured by SOPREMA. All parties agreed that asphalt was the best roofing solution for the facility due to its longevity, durability, and long-term dependability.

Roofing Solutions, LLC, headquartered in Prairieville, Louisiana, was invited to bid on the project. “We were the successful low bidder,” says Tupac de la Cruz, the company’s founder and operations manager. “When we started working on the planning and phasing, we realized the job was going to be an undertaking because, number one, it was a big-size job, and number two, the facility works 24-7.”

Completing the project without interrupting operations would be the biggest challenge on the project. Crews could not interfere with traffic flow and mail deliveries, and would have to protect people and sensitive machinery inside.

“Before beginning the re-roof project, we were given a full tour of the facility,” de la Cruz says. “It was an eye-opening experience to see the equipment, systems, and personnel that manage the mail delivery process from start to finish. You had to coordinate with the facility manager, the transportation manager, and multiple stakeholders to make sure that you did not interrupt all of the conveyor lines sorting all of the mail coming in and out of that facility every day.”

Working in Sections

The deck was exposed to the interior, increasing the risk of dust falling onto the equipment, so Roofing Solutions crews installed a 6-mm protective film using a Spyder lift. “We installed special sheathing underneath the deck to protect the conveyor systems and all of the equipment,” noted de la Cruz. “We also had to protect the workers and make sure that there was no noise, no dust, or any disruptions from anything to do with the roof replacement.”

Sunbelt Vacuum Service was contracted to remove the rooftop gravel. Then the old built-up plies were then cut up and removed by hand. “We had a metal deck, and we couldn’t put any heavy equipment on it,” de la Cruz recalls.

Work proceeded in sections to ensure everything remained watertight. “You had to cover everything you’d demo the same day,” de la Cruz says. “In the summertime in Louisiana, it can rain almost every afternoon.”

The new roof system included two layers of mechanically attached polyiso insulation, which was topped with SOPRABOARD, an asphaltic cover board, which was adhered with COLPLY adhesive. The two ply system was comprised of a base play and a cap sheet Designers chose SOPREMA’s Solar Granule cap sheet membrane, which provides the benefit of high reflectivity. Torches were not allowed on the project, so the membrane was set in cold adhesive. “Because we could not use any torches, all of the laps for modified bitumen cap had to be sheet welded with a robot like you were doing single-ply,” notes de la Cruz.

The roof system specified for the project was a two-ply modified bitumen system topped with SOPREMA’s Solar Granule cap sheet membrane.

Most of the roof area was clear sailing, but access at the jobsite was limited due to the busy transportation routes. “It was a nice, wide roof,” says del la Cruz. “The hardest part was getting the material from one end of the roof to the other, because we only had access at one point. No motorized vehicles were allowed up there, but we were able to use carts to move material from one end to the other.”

The roof features four large raised sections framed with clerestory windows, and the multiple levels sometimes made moving material difficult. “In some cases, you had to bring the material across one level, bring it up to another level and back down again,” says de la Cruz.

The existing skylights were replaced with new single-slope skylights manufactured by KalWall.

Safety and Security

The safety plan utilized mix of guardrails, perimeter flagging, and safety monitors, depending on the configuration of each section. “We also had to have a flagging man on the bottom to make sure we were not interfering with the 18-wheelers coming in and out with their packages,” de la Cruz says. “The project extended over Thanksgiving and Christmas, and you couldn’t imagine the amount of trucking that goes through that facility during Christmas.”

Making sure everyone was on the same page was crucial. Weekly planning meetings were supplemented with daily huddles. “We met with the facility manager every morning to make sure we let him know where we’d be and what we were going to do that day,” de la Cruz explains, “Every afternoon, we’d let him know what the plan for the next day was so they could plan ahead. It was a very proactive approach.”

The crew, which included 20 men during the peak of the project, usually accomplished 3,000 to 3,500 square feet of demo and roof replacement per day. The project was completed in seven months — three months ahead of schedule.

The project was recognized by the Asphalt Roofing Manufacturers Association as the Silver Award winner in the 2020 ARMA Excellence In Asphalt Roofing Awards program, which recognizes industry professionals for their high-performing steep-slope and low-slope asphalt roofing projects across North America.

“We had such pride in completing that project because it was so large and we had zero injuries, no issues, and the client was very happy. We decided to submit it, and we got the award,” says de la Cruz.

“We finished the project about three months ahead of schedule, and we were able to complete the job with no interruptions to the facility. We knew if we could do that, in the end it would be a successful project.”

For more information about submitting a project for the Excellence in Asphalt Roofing Awards, visit www.asphaltroofing.org.

TEAM

Architect: Crump Wilson, Baton Rouge, Louisiana, www.crumpwilsonarchitects.com

Roof Consultant: Wharry Engineering, Garland, Texas, www.wharry.com

Roofing Contractor: Roofing Solutions LLC, Prairieville, Louisiana, www.roofingsolutionsla.com

MATERIALS

Membrane: SG Solar Granule Cap Sheet, SOPREMA, www.soprema.us

Cover Board: SOPRABOARD, SOPREMA

Skylights: Kalwall, www.kalwall.com

5 Considerations for Resilient Zinc Roofing in Coastal Applications

Non-corrosive, non-combustible and self-healing, zinc’s long-lasting performance has been demonstrated its resilience in coastal environmental for more than 200 years. Pictured here is the Nordisches Aquarellmuseum, Skärhamn, Sweden. Photos: RHEINZINK

For centuries, zinc roofing materials have proven reliable in Europe’s marine environments and other extreme climates. In recent decades, the enduring qualities of zinc have gained interest and use in North America. Here are five aspects to consider when working with zinc in coastal roofing applications.

1. Natural Material

Zinc is an abundant natural resource. Based on known ore reserves, the world’s zinc supply is estimated in excess of 200 million tons and expected to last approximately 700 years.

Zinc’s inherent metallic properties allow the material to deliver non-corrosive, self-healing, low-maintenance and long-lasting performance. No paint, varnish or sealants are required, and its run-off is non-staining and non-toxic.

In North America, ASTM B69-16, “Standards Specification for Rolled Zinc,” is the primary reference document for both Type 1 and Type 2 alloys and their expected characteristics. Rolled zinc is efficiently produced by alloying Special High-Grade, 99.995 percent pure zinc with very small quantities of copper, titanium and aluminum. The zinc alloy composition determines whether the metal will tend toward a blue-gray or graphite-gray coloration.

2. Dynamic Appearance

A time-proven, dependable material, zinc roofing products complement both contemporary and traditional architectural styles, and foster a connection to their surrounding natural environment.

Zinc can be fabricated to fit almost any slope, curve or linear run, as well as perforated and fashioned into ornamental accents.

Untreated, architectural-grade zinc is bright, shiny and light reflective. Over time, a natural matte patina develops, creating a dynamic appearance as the material ages. A patina’s formation is a process of the gradual growing together of zinc carbonate “freckles.” The rate of its formation is related to the slope of the surface. The patina will form slower on a vertical wall surface than on a slightly pitched roof. The patination speed varies between six months and five years or more, depending on climatic conditions. The more exposure to wetting and drying cycles, the quicker the patina will develop.

Specific to coastal communities, the natural patina will appear lighter when used in marine locations where the air contains chlorides (salt). Deposits will not be as visible on lighter blue-gray zinc.

Some manufacturers offer pre-weathered zinc material that accelerates the patina formation under controlled conditions. Factory-finished options also are available to achieve an initial, uniform aesthetic.

3. Product Versatility and Variety

A soft, lightweight metal, zinc can be fabricated to fit almost any slope, curve or linear run, as well as perforated and fashioned into ornamental accents. Zinc roofing products can be installed on low sloped, steep sloped, flat and mansard roofs, and used for hip and ridge caps, drip edges, alleys, step flashing, dormers, cupolas, parapets and more.

Seam profiles can be customized to the project’s requirements. For example:

During their many years of use, zinc roofs do not rot, rust or need repainting, and its runoff is non-staining and non-toxic.

· Double-lock and single-lock seam joints between roof panels stand 1 inch or 1.5 inches up from the draining plane. A raised seam height can emphasize the roof as a design element and have a functional purpose in coastal climates with snow.

· Vertical standing seam profiles with mechanical lock connections are the most common zinc roofs.

· Flat seam profiles rely on gravity and at least a 4:12 slope to maintain weathertightness.

· Low-profile zinc shingles and interlocking or overlapping tiles applied parallel to the eave present another familiar aesthetic. They involve a technically easier installation method than vertical joints and always are applied as a “dry-joint” roof system without solder or sealant. Tiles can be small. They provide good wind resistance, but cannot provide the same level of weather protection as a vertical seam.

· For vertical seam profiles, vertical joints are attached to one vertical side joint, overlapped and closed on the opposite side. The soft metal simplifies the task of hand-seaming or power-seaming zinc panels. Long panel lengths can make this design more vulnerable to oil-canning (panel waviness), panel disengagement and wind uplift. Accommodating longer panels, taller seams and those with added capillary breaks offer better water and wind resistance, critical in many coastal applications.

4. Resilient Results

Installed properly, zinc roofing systems will resist corrosion, air and water infiltration, and withstand high winds reaching up to 150 mph. In marine environments that are susceptible to fires, zinc also offers a noncombustible solution.

Common installation considerations and cautions include:

· Zinc roof profiles should be applied as a ventilated dry-joint cladding or a “rainscreen” roof strategy, not as the primary waterproof barrier. This design alternative allows for pressure equalization, backside drying and moisture escape.

As zinc ages and weathers, a natural patina develops to create a dynamic appearance.

· Above-sheathing ventilation mats must be a requirement of every zinc roof assembly. Use an 8 to 10 mm structured underlayment comprised of entangled nylon wire to elevate the zinc roof panel, creating a capillary break with a 0.95 cm airspace to help keep the underside of the profile dry. Do not accept a substitution of this air space and capillary break with a backside paint coating or other barrier strategy.

· Self-adhered high-temperature roof underlayments are recommended. Synthetic felts may be utilized on steep pitch roofs in combination with self-adhered high-temperature underlayments at vulnerable roof conditions and roof penetrations.

· Red rosin paper, conventional felt and any other moisture-holding material should be prohibited in every zinc application and related specification.

· To facilitate moisture drainage from the vented space, the roof panel usually should have a soft bend past the drip edge (cleat). This open hook promotes water drainage from the end pocket formed by the panel hook. Zinc profile end folds also should be “soft” with the raw zinc edge parallel to the ground and not closed tight.

· Excessive use of sealants can plug weep holes, limit airflow, trap moisture, create adverse reactions or restrict the metal’s movement. For any proposed use of tube or tape sealants within laps or other concealed applications, first consult the zinc manufacturer.

5. Sustainability and Longevity

The sustainable benefits of architectural zinc products support criteria for several green building programs including BREEAM certification, the Green Globes system, the U.S. Green Building Council’s LEED rating system, and the Cradle to Cradle Products Innovation Institute.

Important to coastal environments, zinc roofing systems can withstand high winds reaching up to 150 mph. Pictured here is a marina in Sydney, Australia.

Products that have earned Cradle to Cradle certification demonstrate their product’s material does not release any toxic substances during usage, deconstruction and recycling; that it retains its original properties without loss of performance; and that can be re-used as a new item of at least equal value. This is known as upcycling; whereas downcycling results in recycling material to become inferior products, and non-recyclable products will be sent to a landfill. More than 90 percent of zinc-containing products are recycled at the end of their lifecycle.

During their many years of use, zinc roofs do not rot, rust or need repainting. They require very little maintenance. For aesthetic reasons, it is recommended to clean the surface of the material with clean water (not seawater) at least twice a year in maritime climate zones, depending on local conditions. Follow the manufacturer’s cleaning instructions. If the metal is scratched, scuffed or fingerprinted, zinc will heal itself by re-patinating. With time and exposure to wetting and drying cycles, the former blemish will patinate and blend to match.

The resilient performance and natural beauty of zinc has been demonstrated for more than 200 years in marine environments and coastal communities. Collaboration between roofing contractors and zinc manufacturers will help ensure a roof that provides long-lasting functionality and appearance, achieving the best results for the building owner.

About the author: Charles “Chip” McGowan is president of RHEINZINK America, Inc., providing architectural-grade zinc materials for roofing and wall cladding systems throughout North America. He can be reached at charles.mcgowan@rheinzink.com. For more information, visit www.rheinzink.us.