$100 million to $300 million

1. Permasteelisa**

Previous year rank: 1
Headquarters: Windsor, Conn.
Website: www.permasteelisausa.com
Employees: 1,000
**Estimates from Dun & Bradstreet and Hoover's. See "The Silent Players" sidebar.

Permasteelisa Group is a worldwide contractor in the engineering, project management, manufacturing and installation of architectural envelopes and interior systems, according to the company's website. In the United States, the company has headquarters in Windsor, Conn., and locations in Chicago; Corona, Calif.; Miami; Mendota Heights, Minn.; and New York City.

2. Benson Industries LLC**

Previous year rank: 3
Headquarters: Portland, Ore.
Website: www.bensonglobal.com
Employees: 621
**Estimates from Dun & Bradstreet and Hoover's. See "The Silent Players" sidebar.

Benson Industries provides design, engineering, supply and installation of curtain wall and external cladding. Its services include design consultation, system design, prototype testing, quality assurance, project management, fabrication and assembly, and transportation, according to the company's website. The company operates eight locations, five in the United States: Chicago; Dana Point, Calif.; Los Angeles; New York City; and Portland.

3. Trainor Glass Co.

Lindsey-Flanigan Denver Courthouse

Previous year rank: 6
Sales: Up 0.5 percent between 2009 and 2010
Headquarters: Alsip, Ill.
Website: www.trainorglass.com
Employees: 676

Since 1953, Trainor Glass has been providing quality fabrication, design, engineering and installation of glass products and framing systems in virtually every architectural application, including new construction, green building solutions, building rehabilitation, storefronts and entrances, tenant interiors, and custom specialty work. Last year, the company completed the Bank of America Center in Charlotte, N.C., the Austonian in Austin, Texas, Constitution Square in Washington, D.C., the Denver Justice Center in Denver, Colo., Takeda corporate headquarters in Deerfield, Ill., and Legg Mason Tower/Four Seasons Hotel in Baltimore. The company has 22 nationwide offices.

L.A. Live Tower & Residences, Los Angeles

4. Enclos Corp.

Previous year rank: 2
Sales: Down 43 percent between 2009 and 2010
Headquarters: Eagan, Minn.
Website: www.enclos.com
Employees: 200
Locations opened/closed in 2010: Opened a fabrication shop in Harrisburg, Pa., with fewer than 12 employees; closed one location with about 12 employees.

Enclos, a leading facade technology firm, provides comprehensive design, engineering and strategic implementation services for custom facades and curtain wall cladding systems. With 15 office locations, the firm self-performs a spectrum of services while managing a sophisticated global supply chain. Last year, the company completed the 1450 Brickell, Miami, project featuring the strongest curtain wall window system of any commercial building in the nation, according to a release. The company also completed the L.A. Live Tower & Residences, Los Angeles, featuring 34 different glass types, and the Met 2, Miami, featuring hurricane impact-resistant façade. 

5. Harmon Inc.

New World Symphony, Miami Beach Fla.

Previous year rank: 4
Sales: Down 27 percent between 2009 and 2010
Headquarters: Bloomington, Minn.
Website: www.harmoninc.com
Employees: 495

Harmon Inc. has 12 locations nationwide, including its Bloomington, Minn., headquarters, and additional locations in Atlanta; Baltimore; Bolingbrook, Ill.; Boynton Beach, Fla.; Cincinnati; Cleveland; Denver; Golden Valley, Minn.; Orlando, Fla.; Seattle; and Tampa, Fla. The company, a leading glass and glazing service contractor, specializes in the entire lifecycle of a building's glazing needs including curtain wall, storefronts and entrances, interiors, services and maintenance, renovation and green building design for office, retail, medical, education, airport, government and hospitality environments.

6. Walters & Wolf

The Eli & Edythe Broad CIRM Center at University of Southern California, Los Angeles.

Previous year rank: 5
Sales: Down 33 percent between 2009 and 2010
Headquarters: Fremont, Calif.
Website: www.waltersandwolf.com
Employees: 425

Founded by John Walters and Randy Wolf in 1977, Walters & Wolf has expanded its construction scope over the years to include glass and glazing, doors, frames and hardware, as well as precast and GFRC products. Currently, the company designs, manufactures, and installs exterior facades in five locations: Fremont, Calif.; Gilbert, Ariz.; Las Vegas; LaVerne, Calif.; and Mukilteo, Wash.

One Bryant Park, Bank of America Tower, New York City. Photos by Andy Ryan, courtesy of W&W Glass.

7. W&W Glass LLC

Previous year rank: 7
Sales: Up 20 percent between 2009 and 2010
Headquarters: Nanuet, N.Y.
Website: http://wwglass.com
Employees: 175

The family-owned W&W Glass, Nanuet, N.Y., has a 70-year history in the metal and glass industry, including more than two decades of experience in the design and installation of various building enclosure systems including, stick built curtain walls, pre-glazed unitized curtain walls, Pilkington Planar structural glass facades and custom metal and glass enclosure systems. The company is the exclusive North American representative of the Pilkington Planar bolted glass system, and partners with Sota Glazing, Brampton, ON, for its unitized curtain wall work.