U.S. home builders increased significantly their projects in September, this year, but housing permit dropped in the month, adding a mixed picture to the struggling housing market, reported the Commerce Department on Wednesday. For September, U.S. privately-owned housing starts were at a seasonally adjusted annual rate of 658,000, 15.0 percent above the revised estimate for Aug. 2011, and is 10.2 percent above the level of Sept. 2010. Single-family housing starts in Aug. were at a rate of 425,000. This is a 1.7 percent above the revised Aug. figure of 418,000. Privately-owned housing units authorized by building permits, a gauge of future construction, were at a seasonally adjusted annual rate of 594,000, down 5.0 percent from the revised Aug. level, but 5.7 percent above the Sept. 2010 estimate. The U.S. housing industry has been suffering its worst slump in decades since 2007. The sharp home price decline, a persisting credit crunch and continuing foreclosure process are keeping some potential home buyers from loosening the purse strings, a major drag on the overall U.S. economy.