Metal

Figure 8.15 Concrete walk with brick detailing. University of California at Los Angeles, by Ralph Cornell, landscape architect.

Figure 8.16 Brick-surfaced public courtyard and seating area on the Viaduct, in Paris, France.

Figure 8.17 Installing modular concrete units, Amsterdam, the Netherlands. forms as shown in Figure 8.15 or they can be “fine-grained” producing a textural quality such as shown in Figure 8.16 on the Viaduct3 in Paris. The pattern of brick in Figure 8.16 acts as background allowing the water rills and tree wells that were installed to be more prominent. The visual effect is created as if the shapes for the rills and tree wells were cut out of the brick pavement surface. The shade cast from the tree canopy creates added visual interest to the pavement surface. The deep shade pattern, as seen from a walkway above the seating area, suggests a cooler place to get away from the heat of the day. The worker in Figure 8.17 is installing modular concrete units on a bed of sand. Prior to placing a layer of sand, a crushed rock base was first placed, then compacted to 90–95 percent density. The compacted rock serves as the structural base to support vehicle traffic. The sand allows the modular units to be made level. After they are set in place, loose sand is swept between the spaces to secure the bricks in place.

The world of materials can be bewildering, and, for the uninitiated, sometimes daunting.

Take something as common as a nail. Nails not only come in different sizes and shapes. They are also made of different materials, such as steel, stainless steel, aluminum, and for specialized applications are coated, such as galvanized nails. And then there are nails that you apply by pounding in by hand with a hammer or with a power stapler (the nails of a staple are akin to staples). In the construction documents the landscape architect specifies the choice of nails the contractor is to use. The choice is not simple and would depend on the application. In this section we will look at several metal materials and how they are used in landscape architecture.

Steel is a common material used in the construction of outdoor furniture, railings, walkway and decking surfaces, fences, signage, outdoor building structures, such as pergolas, shade structures, and enclosed structures associated with outdoor uses. Steel materials can be composed of a variety of ingredients depending on the intended application. Steel is a manufactured material created through a variety of fabrication processes. When the designer is considering the use of steel for either fastening––such as nails and bolts—or in the fabrication of a designed element—such as a bench, railing, or outdoor structure—the type of steel must be considered, followed by a technical specification. The primary ingredient of steel is iron. Iron is a metal produced from quarried iron ore4 and in a furnace in combination with coke and other materials. It is then processed into other materials, including these common products: steel (rolled and cast), wrought iron, and stainless steel. These materials can then be further processed into a rolled form for later fabrication into a great variety of products, cast with the use of a mold into modular units, and welded together to make girders and other structural steel products. A reinforcing bar is a product of steel used primarily to increase the structural properties in the construction of concrete walls, footings, and pavement. Part of the responsibility of the designer when specifying steel or any metal product is to indicate the type of steel and other desired pertinent physical properties required, depending on the application. For instance, a steel bench could be made from wrought or cast iron, stainless steel, or fabricated from rolled steel. Detailing must further specify the product dimensions, the surface treatment (galvanized, acid, baked enamel or other product), and method of assembly (fasteners or welded) described in the technical specification requirements. Figure 8.18 is a steel shade structure constructed from a product called corten steel or under the trademark: Cor-Ten. Cor-Ten is a steel alloy formulated to eliminate the need for painting or surface treatment. When installed, it is allowed to weather (corrode) to form a rust-like, stable finish. Other forms of steel products, if left untreated without a protective coating (such as paint and galvanized

Figure 8.18 Steel shade structure, Phoenix Botanical Garden, by Steve Martino, landscape architect.

Figure 8.19 Reinforcing bar used to create a see-through wall or fence at a residence in Scottsdale, Arizona, by Steve Martino, landscape architect. Figure 8.20 Woven sheet metal wall, Scottsdale, Arizona, by Steve Martino, landscape architect.

treatment) will corrode or rust. The corrosion process, if left uncorrected, may result in structural failure. In Figure 8.19 the landscape architect has designed a see-through fence or physical barrier with the clever use of a common steel material: the reinforcing bar. This fence detail is an example of the range of innovations available to landscape architects when selecting and designing with different materials. Sheet metal (ferrous or aluminum) is another form of steel that comes in rolls for later use in fabricating landscape features, such as the fence shown in Figure 8.20. The steel used is an alloy developed to resist rusting or corrosion. The fence was constructed on the site using rolls of the material woven between upright reinforcing bars anchored in a concrete foundation. Aluminum is another common metal used in the landscape. Figure 8.21 presents an area barrier that was designed to have a dual purpose: as a continuous bench and a crowd barrier. The protective railing shown in Figure 8.22 was fabricated from aluminum. The pieces were arranged into a cat-tail motif, and welded in a shop into panel modules prior to installation on site. Wood is one of the most often used materials in the construction of features designed by landscape architects. The world of wood can be as confusing to students as metal can be. The specifications and options for wood can be extensive. One needs to specify the tree species of the wood source (pine, fir, redwood, teak, etc.) as well as how the wood was cured (dried after being milled from the trunk), the location of the wood from within the trunk (heart or an outer layer), and whether or not it has been treated, such as pressure treated to resist rotting. One also must specify if the wood is to be free of Figure 8.21 Aluminum bench–railing combination, 2008 knots, and how it is positioned into place, whether Summer Olympics, Beijing, China. the “curl” of the wood grains is facing up or down.

Figure 8.22 Metal railing, Lake Austin, Texas, by TBG Partnership.

Depending on the application, further specifications might be needed to ensure the correct wood product is used, fabricated correctly, fastened with the appropriate fasteners (for instance, iron, brass, or stainless steel bolts or nails), and finally finished with the correct paint, stain, or other surface treatment. To mention in passing, the choice of finishing products also requires careful consideration. Choosing the correct type of paint or stain is the responsibility of the landscape architect.

Wood is an adaptable material for a great many uses in the landscape. Wood is used in the fabrication of outdoor furniture. The two different benches shown in Figure 8.23 were made from different wood materials, surface treatment, and fabrication details. Wood is also used in the construction of fences and railings (Figure 8.24), and decks (Figures 8.25A and 8.25B).

Figure 8.23 A: Wooden bench, Telefónica office campus, Madrid, Spain; B: New York City High Line wood benches, by James Corner, landscape architect.

Figure 8.24 A: Wood boardwalk with wood railing, wildlife visitor center, Louisiana; B: Boardwalk providing access across marsh, Marin County, California.

Figure 8.25 A: Wooden pedestrian deck, Zud Park, Rotterdam, the Netherlands; B: Wooden stage, and covered structure, Discovery Green, Houston, Texas, by Hargreaves and Associates.