Snap-Lock Standing-Seam Metal Roof Installation
Factory-made panels and flashing go together without specialty tools or subcontractors.
When you’re a remodeler in a rural location, you often have to venture into uncharted territory because there’s nobody else to do the job. This was the case on a recent project when I was asked to install a standing-seam metal roof as part of a major remodel. Although the roof was relatively small, it had nearly every complicating element you can think of: valleys, doghouse dormers, slope transitions, and even skylights. Our company specializes in difficult roofing projects and I take pride in our sheet-metal skills for flashing and built-in gutters, but I had never attempted a standing-seam roof. My crew and I had to figure it out on our own. To ensure our roof was done right, two of my employees and I attended a two-day training at the manufacturer’s headquarters in preparation. This article describes everything we learned while installing this complicated roof.
There’s more than one kind of standing seam
There are two basic styles of panel for standing-seam metal roofs: field seamed and snap lock. Field-seaming requires the joints at the panel edges be crimped together as each piece is installed on the roof. This is the traditional installation method, and it calls for some expensive specialty tools. The big advantages of field-seamed standing-seam roofs are their traditional look—owing to the imperfections in the field-made seams—and their low-slope capabilities (down to 1⁄2-in-12).
Snap-lock panels are manufactured to be put together without expensive mechanical seamers. Instead, they lock together with a few bumps of your fist. The installation method saves time and produces perfectly straight standing seams. In this case, the client wanted perfectly straight seams, so snap-lock panels were the better choice. Both types of panels are secured to the roof using metal clips that allow the panels to expand and contract with changes in temperature.
After deciding which type of panels to use, the next step is to choose the type of metal. Although standing-seam panels are sometimes made from copper, stainless steel, and even zinc, most are rollformed from coils of painted steel and aluminum. The fluoropolymer paints that cover the panels and flashing are better known by their brand names, Kynar and Hylar, and have a reputation of unsurpassed durability, including the ability to endure complex forming without cracking.
The choice of aluminum vs. steel involves several factors. Steel panels are stronger in comparable thicknesses, so they’re more often used in steel-framed commercial buildings because the panels can span the longer distances between framing members. That said, scratches on steel panels will rust, as can cut edges like those at eaves and valleys, staining the roof and surfaces below. Aluminum doesn’t have this corrosion problem, but it is typically more expensive. However, currently the commodity price between steel and aluminum is so close, we opted for .032-in.-thick aluminum , which was only slightly more expensive than a steel roof. This roof is expensive (nearly $30,000 in materials) and it took almost three weeks for us to install, but it looks great and will last a lifetime.
From FineHomebuilding #272
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