In the housing bust, many glass manufacturers went out of business or mothballed operation.

Source: Glass Shortage Has Skyscraper Costs Soaring: Got Glass? – Mike Shedlock – Townhall Finance Conservative Columnists and Financial Commentary – Page 1

NEW YORK—A shortage of glass is taking a toll on the United States’ commercial building boom, adding millions of dollars to the cost of new skyscrapers and halting some projects midway through construction, according to an article in the Wall Street Journal (subscription required). Demand is also increasing rapidly for curtainwalls. Hundreds of thousands of square feet of glass is needed for a typical high-rise office tower. Glass manufacturers and fabricators can’t keep up. Many glass makers suspended their operations or went out of business during the recession. However, apartment buildings are being built at their fastest pace in decades, and new office towers are being built at the fastest rate since the early 1990s. Restarting idled glass factories is a costly and time-consuming process, so property developers say the current shortage could last well into next year, if not longer.