Building & Construction

Uses for aluminum profiles in the building and construction industry cover a wide range of products, including windows, doors, railings, bridges, light poles, high-rise curtainwall, framing members, and other various structures.

Commercial construction relies heavily on the structural strength, long life, and corrosion resistance of extruded aluminum fenestration products that use advanced technologies to provide the best thermal performance available. New construction projects make extensive use of aluminum’s structural strength, including the 700,000 pounds of extruded aluminum profiles used in the curtain wall and 180-foot-long movable glass end-zone doors of the new Dallas Cowboys NFL football stadium that will opened in 2009.

Building renovations increasingly use extruded aluminum windows and doors for a customized retrofit that blends seamlessly and harmoniously with the structure’s historic context, such as the Empire State Building and the Statue of Liberty. Recycled content for aluminum building products is on the rise, and reuse and recycling give aluminum the double advantage of environmental and economic benefits.

Architectural product designers are taking full advantage of extruded aluminum’s potential as the ideal support/framing material for leading edge building-integrated photovoltaic (BIPV) curtain wall systems, and photovoltaic (PV) modular solar panels. European trends toward PV systems, and ventilated and computer-controlled automated exterior blinds and metal shading systems in commercial structures are catching on quickly throughout North America, drastically improving a “green” building envelope’s energy efficiency by maximizing use of natural daylight, while minimizing solar heat gain. Such systems are being fully integrated into the building envelope in designs that are visually striking, as well as highly functional.

Corbin Bridge, located in Pennsylvania, was refurbished with an extruded aluminum deck. It has a 320-foot span, and the deck is 12 feet, 6 inches wide (single lane of traffic).Because the dead weight of the aluminum is so much less than that of the original construction of steel and timber, it can now carry live loads of 22 tons, compared to the 7-ton limit prior to replacing the deck. What this means in practical terms is that a fire truck can now cross the bridge, which it could not have done previously.

The ability to be formed and to accept a high-grade paint finish makes extruded aluminum particularly appealing for use in construction. With superior heat properties and structural integrity, extruded aluminum is an ideal choice for constructing unitized curtainwall panels. Using thermally improved extruded aluminum profiles adds to the energy efficiency of the building, delivering reduced heat loss/gains and interior condensation resistance, in addition to assisting with overall energy conservation. Aluminum's weight-to-strength ratio saves on overall bulk compared to alternative materials and allows for greater design flexibility. Case-in-point, thin-walled aluminum extruded sections can withstand forces of lateral buckling and high winds, a significant concern with high-rise buildings.

Photo: © James Steinkamp, Steinkamp/Ballogg Photograph. Used with permission from Goettsch Partners, Inc.

Modern aluminum windows are attractive, energy-efficient, and reliable. Thermally-broken aluminum window-frame-and-sash construction is appropriate for use in all climates. Such windows also possess a number of other advantages that make them the best choice both for new construction and replacement.

Performance with Minimal Maintenance
Aluminum is a stable material, with consistent and predictable properties. It doesn't absorb moisture, so it won't swell, shrink, warp, twist, split, crack or check. It can't rust. Its strength and rigidity are unaffected by weather and time. Expansion and contraction, both of the building and the window-frame materials, are two of the factors that determine long-term window reliability and ease of operation. Over time, aluminum windows are resistant to changes in temperature and humidity, which can cause some window-frame materials to bend and twist leading to seal failure, air and water leakage, and difficulty in opening and closing or swinging and sliding window elements. Aluminum is a stiff material--23.2 times stiffer than vinyl, and 7.2 times stiffer than soft wood--so aluminum windows are more resistant to distortion caused by building movement.

Moreover, aluminum windows are available with long-lasting baked enamel or anodized finishes, adding to their beauty as building components and ensuring freedom from frequent repainting. Aluminum windows' unique combination of enduring properties means long-term performance with minimum maintenance. Today's aluminum windows use long-lasting weather seals that can be easily replaced after years of service. To maintain attractive appearance, all you have to do is wipe with a damp cloth to remove surface dirt.

Total Thermal Performance
Windows lose heat in several ways: largely by conduction and radiation through glazing; by conduction through frames; and by air leakage. Today's effective sealing materials minimize air leakage around glazing and through the variety of joints. In aluminum windows, thermally-broken framing members minimize conduction heat loss through frames. These are usually composed of three pieces: an outer extruded frame; a central core of insulating material; and an inner extruded frame. The central core acts as a barrier to heat flow from a warm interior to a cold exterior in winter, and vice-versa in summer.

This modern construction creates highly thermally efficient frames and enables window manufacturers to take advantage of other important aluminum properties-durability, strength, stability and corrosion resistance--for the benefit of consumers. Manufacturers today use a variety of glazing methods and frame designs to minimize window condensation, which can be damaging if it occurs on window frames. By using "thermal breaks" they make aluminum windows with condensation resistance similar to that of wood and vinyl windows.

It's important to note that heat loss through glazing is independent of the material of which sashes and main frames are made. It's the same for windows with frames of aluminum, wood, or vinyl. The total original (i.e., at installation) thermal efficiency of a window is a measure of its ability to resist heat loss through glazing, frames, and by air leakage through joints. Today's aluminum windows offer similar original thermal efficiency to those of wood and vinyl--plus the additional advantage of long-term durability, strength, stability, and freedom from structural deterioration.