Time was, when you speced windows for an apartment building or condo, you probably chose aluminum. You probably didn't think too much about sound-transmission ratings or impact resistance. Energy efficiency may have been an issue, but seismic concerns were off your radar. Consult a historical review board? Not likely.
Then again, maybe you did think about these matters, but your client considered them too costly and overruled your recommendations.
"Commercial residential buildings did not pay attention to these issues," says John Cane, manager of technical services for TRACO, a window manufacturer based in Cranberry Township, Pa. "It seems like commercial residential was so driven by price that one of the ways it cut costs was with low-end windows."
The typical low-end window was made from non-thermally broken aluminum and had single-glazed panels. This is good news for manufacturers like TRACO, because they've made a strong niche business out of replacing shoddy windows with well-shod versions.
Today, regional code requirements have made choosing windows more important. Run of the mill won't pass tough hurricane standards in Miami's Dade County, energy-efficiency edicts in California, or seismic rules anywhere on the West Coast. Additionally, most major cities now have sound-transmission require- ments, and if you're thinking about replacing windows in a historic district without consulting the local preservation board, better think again.
Fortunately, manufacturers have made advances in window materials and features to help you meet those code requirements. Aluminum is still a preferred spec, but improvements have solidified its status as the architect's best friend. "It's prized by the architect because it offers a clean contemporary look," says Scott Becker, AIA, of Baylis Architects in Bellevue, Wash. "And now with a thermally broken sill it offers very good energy performance."
Other materials have emerged as well, or crossed over from other applications. Vinyl, for instance, is now an appropriate spec for multifamily buildings, and hybrids like aluminum-clad and vinyl-clad wood are increasingly common. "We have used vinyl in our four-story projects," says William Higgins, AIA, principal of Architecture International in Mill Valley, Calif. "It's becoming very popular." Cane agrees, calling the development of these materials among the window industry's biggest achievements in some time.
Many products from familiar manufacturers, such as Bayport, Minn.-based Andersen Windows or Tacoma, Wash.-based Milgard Windows, are appropriate for low-rise multifamily projects. Anything from Andersen's commercial and residential lines can be installed in projects up to four stories tall. Milgard offers a complete line of applicable products, including the vinyl Quiet Line windows, which have commercial-grade ratings and sound-transmission class grades of 41 to 47.
Windows for high-rise projects are a different matter. "Wind-load requirements on a high-rise building are very high, so it limits the systems we can use," says Jon Starr, architect with San Diego-based Carrier Johnson. "But we still have a lot of options. We can use a mix of punched windows, curtain wall systems, and storefront framing." For those styles, you have TRACO; Monett, Mo.-based EFCO; Orange, Conn.-based Crit-tall Windows; Wausau Windows and Wall Systems in Wausau, Wis.; and Miami-based R.C. Aluminum, among others.
TRACO offers custom aluminum windows in any size, color, shape, and style--from single- to double-hung, casement, projected, fixed, or sliding. The company also manufactures "ribbon" windows that run around the perimeter of a building's floor, and high-performance glazing to meet most energy-conservation requirements.
"We just started in California," Cane says, "and we see quite a demand for our windows. Up until the energy crisis, most people in California thought single-glazed windows were fine. Now, all of a sudden, they are interested in insulating glass."
EFCO Corporation makes aluminum projected, hung, sliding, and special-purpose windows, plus various storefront and curtain wall systems. Product manager Judi Walker says the company sells beefy systems for waterfront and high-wind areas, including some products that have passed Dade County codes. "Those systems require bigger frames and heavier metal," she says, "and the glazing is very important for missile impact."
Beg, borrow, steel
For the cost-is-no-concern project, there's steel. Three times stronger than aluminum, steel permits architects to design large expanses of glass. It also allows extremely thin sight lines. "It's the reason architects spec us," says Bill Turso, vice president of sales at Crittall Windows in Orange, Conn. "It's an aesthetics thing." In addition to its good looks, steel costs less to maintain and has the best ecological life cycle of any window material, he says. Crittall makes hot-rolled and hot-dipped galvanized steel windows in almost any configuration, size, or style.
Despite steel's strengths, some architects are wary of specing it, especially in climatologically challenged areas. Says Higgins, "Steel windows are great for sight lines but there's a tradeoff in certain locations. Steel windows transmit heat through the frame, which heats up the living space. Aluminum, on the other hand, has a thermal break between the aluminum and the glazing." Becker adds that because steel is not thermally broken, you get unwanted heat loss and heat gain.
But Turso says that steel now has the ability to hold insulated or dual glazing, and some units are double weather-stripped depending on the application.
If replacing inefficient windows is not an option, retrofitting your project with V-Kool clear window film might be. The manufacturer says the film blocks 99 percent of ultraviolet rays and 94 percent of heat-producing infrared rays. More important, says Dave Stanley, national accounts manager for Houston-based V-Kool Inc., the film maintains 73 percent of precious visible light. "You can use it anytime you don't want to change the aesthetics of the building," he says.
V-Kool costs $9 to $12 per square foot installed, which must be done by a qualified representative. Larger projects may cost less per square foot, and you can save money by applying film only to the side of the building that has extreme exposures. Says Stanley, "The naked eye will not be able to tell the difference." Also available is V-KOOL Secure, a shatter-resistant film that provides protection from flying objects.
While specing windows is always an expensive proposition in residential construction, its effects on the budget are geometric in multifamily building. In fact, much of a project's cost comes down to glazing, says architect Higgins, so keep in mind that "less glass means more savings." If you absolutely must have all that glass, consult your window reps for suggestions about less expensive materials or configurations.
And, finally, when opening a job to bidding by manufacturers, always make sure specs are clearly and concisely written. Says EFCO's Judi Walker, if specs are consistent, you'll get a better product at a fairer price.