Except as provided in 25.603, use only unmanufactured construction material mined or produced in the United States, as required by the Buy American statute or, if trade agreements apply, unmanufactured construction material mined or produced in a designated country may also be used. [75 FR 53165, Aug. 30, 2010, as amended at 79 FR 24209, Apr. 29, 2014]