West Building Skylight Project

West Building Skylight Project Schedule

The West Building was designed by architect John Russell Pope and constructed between 1937 and 1941. The skylights in this building are a remarkable feature of the original design. Covering nearly the entire roof, an area of approximately three acres, they allow brilliant natural light to illuminate and enliven the interior, giving the Gallery visitors a sense of the changing weather above. Over time, the skylights have suffered from exposure to the elements and have deteriorated significantly, and a major project is nearly complete to replace them.

Outside, the skylights are deliberately hidden from view by high parapet walls so that their surfaces, glittering in the sun, do not distract from the building's unified, neoclassical form.

Inside the building, a huge attic space lies directly below the skylights. Natural light enters the exhibition galleries through glass panels or "laylights" in the attic floor, which are visible from the rooms below. Conservation research shows that works of art must be protected from ultraviolet light, and several years ago, special ultraviolet-absorbing plastic panels were placed over the "laylights."

In the original skylight system, panes of 1/4 in.-thick wire glass were held in place by metal cap strips secured to sloped aluminum framing. Crews whitewashed the skylights each spring to reduce the heat and brightness of the summer sun filtering into the building. The whitewash, which breaks apart with the first hard frost, is eventually washed off by early winter rains.

After 55 years, the skylights gradually became unreliable. Several years ago, ingenious inflated plastic covers such as those used for temporary greenhouses were installed over the skylights for short-term protection. These plastic covers, however, have a limited life expectancy and required extensive maintenance.

In 1996, the skylight replacement project began. It has taken place in four phases above the four quadrants of the main floor galleries. As work progressed overhead, each phase necessitated that portions of the permanent collection in the galleries below be temporarily relocated to the ground floor and to adjacent main floor galleries. As the project nears its scheduled completion in July 1999, works from the permanent collection are being returned to their usual main floor locations. This reinstallation period will continue through early September 1999.

Glass Panel Design

Specially designed glass panels are the most complex element of the new skylights. Each panel is an insulated glass assembly composed of three sheets of glass. The outer sheet is tempered to increase its resistance to breakage and is treated with a low-emissivity coating to reduce heat loss. The inner side of this sheet is covered with an opaque ceramic frit in a dot pattern. The frit dots are designed to reduce light entering the building by 40 percent, but still permit a sense of outside weather conditions in the exhibition galleries below. The two inner sheets of glass are heat-strengthened and specially manufactured with low iron content to avoid the inherent green color of standard window glass. The two glass sheets are laminated with a clear polyvinyl butyral sheet that blocks harmful ultraviolet light. The outer and inner glass is separated by a sealed 1/2 in. insulating air space. Typically, the glass panels are 1 3/16 in. thick, approximately 2 feet wide by 10 feet long, and weigh 200 pounds.