Construction spending in the U.S. unexpectedly rose in September, led by increases in homebuilding and public projects. The 0.5% gain brought spending to $801.7 billion, Commerce Department figures show. Schools and new transportation grids accounted for most of the gains. Public construction climbed 1.3%, federal construction outlays increased 6.1%, and state and local government spending rose 0.8%. Private commercial projects dropped 1.6%.