BOSTON (MarketWatch) -- The problems in U.S. credit markets are beginning to affect nonresidential, commercial construction across the country, according to a survey released Wednesday by the American Institute of Architects. "The apprehension in the industry is based around reports that growing default rates among subprime borrowers in the residential market has made credit more difficult to secure for nonresidential construction projects," said AIA Chief Economist Kermit Baker in a statement. Subprime aftermath ???