Lawrence firefighters check for hot spots in the walls of the Bum Steer Bar-B-Q, 2554 Iowa, after a fire caused about $3,500 in damage Friday night. Battalion Chief Jerry Karr said the cooker room caught fire when workers burned cardboard boxes in the metal container used to heat the cooker. Excessive heat ignited grease and meat in the cooker at about 6:44 p.m., Karr said. The fire spread out of the cooker, but was confined to the cooker room in the northeast corner of the building. Firefighters had the fire under control by 7:10 p.m. They then broke through the ceilings and walls of the cooker room to confirm that the blaze hadn't spread to the building's structure. "We had to make sure the fire wasn't hiding in a corner somewhere," he said.