Metal roofing applications offer a mix of flexibility, durability, and attractiveness.
Walls surround the three learning gardens at Community Consolidated School District 59’s (CCSD59) Early Learning Center. In each garden, one of those walls is covered in metal panels. It tilts inward, and its window patterns jog up and down as if imitating the activity in the gardens. What is not apparent from the gardens is that the metal that covers those walls continues onto the school’s roofs.
The roof, also known as “the fifth façade,” is not the most glamorous aspect of the designer’s output. However, as one of my colleagues often says, “Although the roof only covers about 20% of a building’s surface, it protects 100% of what’s inside that building.”
Therefore, I will wrap up this series on metal by exploring the material’s roofing applications. Metal roofing systems offer a protective element that other materials with smaller sized pieces cannot achieve. Slate, for instance, can only create small pieces that must overlap. With metal, designers can play up the material’s larger scale capabilities to achieve roofs that make it much harder for water to penetrate.
From an aesthetic standpoint, metal offers an incredible texture and surface beauty. Additionally, its lightweight nature and durability allow designers to extend roofs much farther than they could with a traditional material like wood. For instance, I recently saw a transit center canopy with gently bent metal roof shingles that create an abstraction reflecting the forward-moving nature of the building’s function.
Water, Wind, and Sun
Shingled roofs, designed to accommodate water flowing downhill, are highly vulnerable to strong winds, which force water in the opposite direction of gravity and onto the substrate (i.e., structural deck or insulation). That results in leaking. Metal panels, on the other hand, enable roofs to be designed so that there are no negative effects when water is forced uphill. Metal roofs don’t perform as well in a flat application, so it’s best when they are installed on a steeper slope to better shed water.
When properly designed, most metal roofs can withstand high-speed winds. If owners are willing to bear the expense, metal roofs can even be designed to withstand hurricanes. Edges, upper ridges, valleys, and eaves are the most vulnerable parts of the roof. A well-designed metal roof can perform better with these elements than roofs created with slate, asphalt, or wood shingles.
Due to their highly reflective nature, metal roofs can also reduce the toll on HVAC systems compared to other materials that tend to absorb the sun’s heat. Additionally, from a life cycle perspective, long-lasting metal roofs are less expensive than their traditional counterparts and are highly recyclable.
Roofs and Walls Unite
Roofing systems can also seamlessly integrate with wall cladding to create a strong expression. The CCSD59 Early Learning Center design, inspired by the adjacent junior high school’s mansard roof edges, features a bent plate of metal panels on its roof and south-facing walls.
The sloped roofs accommodate various ceiling heights throughout the addition and bring classrooms more natural light via clerestories (high windows) on the north edge. The shed-style roof also relates to the massing of the homes across the street.
Since the metal wall construction locates the vapor barrier along the exterior face, the cavity formed by the canted (i.e., tilted) wall becomes an opportunity to conceal gutters and downspouts within, creating a more uninterrupted roof-to-wall transition.
I am by no means suggesting that metal roofs are the best solution for every facility. Nevertheless, when it comes to the fifth façade, any building owner considering a new facility, addition, or renovation would be wise to explore metal.
See Ted’s other posts about the use of metal in architectural design: Introduction, Endless Possibilities, No More Thermal Bridging.
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