Fort Washington Research Center, Cambridge, Mass.
The architects at Arrowstreet Inc. had a familiar challenge when they designed the state-of-the-art biotech lab and office space for Lyme Properties and its sole tenant Vertex Pharmaceuticals. The four story, 190,000-square-foot facility is part of the Fort Washington Research Center in Cambridge, Mass.
“This is an edge neighborhood and we wanted to bring in elements of both residential and industrial surroundings,” said architect James Batchelor. “At the same time, we had to make sure the building met the practical and aesthetic requirements of a biotech tenant. The building was fully leased as soon as ground was broken. To me, that is tangible confirmation that we met our objectives.”
One way they achieved that balance was through the use of zinc shingles.
It is just one of the many commercial projects across the nation that relied on the durable and aesthetically appealing material that has been a staple of European architecture for so many years. Architects and builders point to a number of reasons they are turning to zinc.
Zinc applications need little or no maintenance. Properly detailed and installed, zinc is extremely durable. It lasts 80 to 100 years as a roofing material and upwards of three centuries as a wall finish. It is important to keep in mind that the longevity applies to monolithic zinc, not surface-coated galvanizing.
The durability comes from the inherent ability of zinc to form a protective coating, known as patina. The patina forms over several years, combining carbon dioxide from the air with water to create zinc carbonate or zinc chloride in a maritime environment. Condensate cannot be allowed to form between the metal and the substrate; it must be detailed and installed according to the manufacturer’s requirements to ensure durability. Zinc needs “to breathe.”
For use as a building material pure zinc is alloyed within strict European standards. Alloying with small fractions of titanium and copper adjusts material properties, including tensil strength, hardness and color.
Zinc use is not specific to any geographic area. Though temperature may influence how a craftsman works with the material, it is as comfortable at high altitude in extremes of cold as it is in hot desert or wet maritime environments.
As a flexible material, zinc can be used in both traditional and cutting edge, modern signature solutions. In traditional buildings zinc is replacing lead for domes, copulas and flashing. It is easily formed into shingles, flatlocks or tiles.
The ability to profile zinc into corrugated, trapezoidal profiles makes the material also an attractive option for industrial type applications. As modular panels, zinc is appropriate to rain screen technology employed on contemporary and high-rise structures.
Architects are specifying zinc out of environmental concerns. Zinc is available globally in large quantities. Finished goods have a low primary energy content. The material is ultra-violet and temperature resistant and non-combustible. In addition, it is easily recycled, consuming as little as 5 percent of its primary energy content.
Metal Work
As we look toward other reasons for the growth of zinc, we look to the evolving face of those working in the field.
There is a renaissance in the crafted metal trade. Trade schools and manufacturers are training craftsmen to work in zinc. Metal smiths are discovering that their skills of working with copper can be directly applied to zinc, as the materials work similarly. Zinc, however, is stiffer than copper, requiring more strength to fold. Folds are characteristically softer and more rounded than other metal, and notching requires cutting to a punched hole to prevent stress build-up. Through their training and their work metal smiths are learning the idiosyncrasies of zinc.
There is a pleasant variability to zinc. Don’t expect a painted reflective finish. The gloss on “pre-weathered” material diminishes to a matte 14.5 percent reflective blue-gray after a few months of weather. Each building elevation will weather differently in relation to the prevailing winds and develop its own slightly different range of patina color. Roof material will age differently than wall material providing another dimension to the architecture.
