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Installation Excellence

Details make the difference in high-quality metal tile projects

Properly Staggered Tiles March18 1
Properly staggered metal tiles. Photo courtesy of DECRA Roofing Systems Inc.

To correctly install metal tile roofs, contractors plot out and complete a battery of tasks. They follow manufacturer instructions, determine whether a project should be a roof-over or tear-off, and address existing masonry conditions. They plan the staging, installation sequence and details.

Follow the Instructions

Carefully following manufacturer instructions is essential for high-quality installations. Matthew Albrecht, installation training and technical manager at DECRA Roofing Systems Inc. in Corona, Calif., says, “Not taking the time to review the manufacturer installation instructions is the biggest error I come across. Most errors can be prevented by taking a few minutes to review instructions.”

Manufacturers offer training classes, typically through their distribution channels. “Oftentimes manufacturers have banks of information from past experiences that can be accessed by simply making a phone call,” Albrecht says. “Any first-time user of a product should contact the manufacturer to review the specific details of their job, ask their rep or trainer what to expect, and ultimately avoid a bad experience.”

For unusual conditions that manufacturers don’t have specific instructions for, Vince Guerra, owner of Metstar USA Inc. in Buffalo, N.Y., says contractors should build based on how water and wind will interact with the roof. “In special or out of the ordinary details, the manufacturers don’t always have all the answers,” he says. “Keep it simple and always make sure you think like a drop of water that is pushed down by gravity, but also pushed up by wind, downpour overflow and ice damming.”

Photo courtesy of DECRA Roofing Systems Inc.

Roof-Over Versus Tear-Off

In some, but not all cases, metal tiles, shakes and shingles can be used to roof-over an existing roof. Roofing over can reduce labor costs and landfill waste. Whether roofing over is a viable and beneficial option for a metal tile retrofit is determined by local building codes, condition of the roof and owner preferences.

Leon Nault, president at Triple Crown Roofing Inc. in Zephyrhills, Fla., says, each house his company works on represents unique challenges and requires different techniques to follow. Some municipalities in Florida allow roofing over one layer of material in good condition; others don’t. But Nault says it’s equally important to ask customers what they want rather than tell them what should be done. “What I ask each homeowner, after I find out if we can indeed go over the existing roofing, is do they feel comfortable with us installing the metal over their existing roof, and if their insurance company requires them to remove the old shingles.”

Some metal tiles are installed directly to roof decking; others attach to battens and/or counterbattens. Synthetic underlayments can be used for roof-over projects. Flashing details are the same whether the existing material is removed or not, Nault says. Regardless of product or method, the levelness of the installation surface determines the flatness of the finished roof.

Jim Sardegna, light commercial manager, Americas, at DECRA Roofing Systems, says, “For an existing layover, oftentimes the manufacturer will require the surface to be as flat as possible, which might require curled up shingles to be knocked off. Rule of thumb: the flatter the surface, the better the install.”

Masonry Repairs

Metal tiles are among the most expensive roofing materials in initial cost. To ensure longevity and return on owner investment, existing masonry and other components must be in a condition that matches the service life of the new roof.

Todd Miller, president at Isaiah Industries Inc. in Piqua, Ohio, says, “One common problem I see is a failure to address masonry issues on the home prior to the roof work. Metal roofing is a long-term proposition. Any intersecting masonry, stucco, or other walls and chimneys really need to be brought up to the same level of anticipated life as the metal roof. It is up to the salesman to help the homeowner understand the need for this and ensure it is taken care of. Nothing can be worse than having to tear into a nearly new metal roof installation because the chimney is leaking.”

A similar issue exists with skylights. “I recommend that any time there are existing skylights that are 10 years old or older, they be replaced as well when the roof is replaced,” Miller adds.

Miller says another problem he’s noticed is estimates that don’t take into account the cost of installing correct wall flashings. “Wall flashings should go behind or be cut into existing wall coverings in virtually all cases,” he explains. “This is a costly procedure, though, and is often skipped by the project estimator in order to make their bid more attractive to the property owner. That really is the wrong approach. Instead, they need to explain to the property owner why these things must be done correctly. That will help them to stand apart from other bidders and help the owner understand the value of their roof proposal.”

Improperly staggered metal tiles. Photo courtesy of DECRA Roofing Systems Inc.


How a project is staged, the order in which the roof is covered, and how flashing and other details are done directly affect long-term performance.

“Some jobs will require special custom flashings or other work; that is why every job must be looked at individually,” Miller says. “You’re also studying the roof to determine the order in which different roof planes will be handled. You’re always looking for ways to minimize foot traffic on the roof based upon the order in which you tackle different roof sections.”

Proper staging affects the quality of the installation and jobsite safety. When choosing how to stage a project and which crew to use, Albrecht recommends positioning workers at stations where they are well trained for tasks.

“While it is important for everyone to have a basic understanding of all aspects of the installation, it’s often most productive if individuals can specialize in one task,” he says. “For example, one that specializes in installing accessories and flashings, one that focuses on laying and installing panels, and it’s always important to have someone on the ground who can feed materials and make cuts.”

Albrecht says proper staging is also essential to overall job-site safety. “Whenever possible, all cutting should be done on the ground. Ground area around the roof should be roped/taped off in case materials were to slide off. Smooth surface metal tile and shingles may require hook ladders to avoid sliding down surfaces.”

In addition to precise staging and sequencing, a high level of attention to details must be given to every step taken throughout the installation. From the moment materials arrive on job sites, Nault says his company pays close attention to how everything is handled and protected. “I have seen delivery companies unload the boxes [of metal tiles] and drop them on a corner of the box; this will distort the locking mechanism,” he says. No amount of sealant can compensate the damaged tiles. “Installers sometimes count on caulking or sealant as a flashing material; flashing must be used to divert the water from ever getting to the underlayment.”

Sardegna says one detail contractors should keep in mind for some direct-to-deck products is to notch their clip-locks when inserting panels into accessories including valleys, rake channels and sidewall channels. Additionally, they should know and observe where water will channel out at the bottom of channel accessories to avoid drainage problems.

For horizontal panel systems, from an appearance standpoint, Sardegna says the panels must be randomly staggered to look right. “If not, this severely detracts from the aesthetic beauty of the metal tile install. Installers need to work with three to four various sizes of panels that they cut on the ground when working out of the valleys, hips and other intersections.”

Photo courtesy of Metstar USA Inc.