A SHED fire at the abandoned John Valves factory site caused $20,000 damage yesterday.Police were forced to block off Norman Street between Creswick Road and Dowling Street for about 30 minutes while the blaze was controlled.Sergeant Dave Collins said the fire was "obviously deliberately lit" and caused $20,000 in damage.Six fire trucks from Ballarat, Ballarat City and Wendouree fire brigades were called to the fire that was reported about 10.35am.CFA operations officer Matt Gardner said it was not known how the fire started. "It's under investigation at the moment," he said."We did manage to save a couple of sheds but one is completely burnt out."Given the age of the buildings, there were initial asbestos concerns but all preventative measures were taken, according to Mr Gardner.Anybody with information is asked to contact Ballarat's crime investigation unit on 5336 6080.