Lumber piled in the vacant Black Angus restaurant was set ablaze Sunday morning, but the sprinkler system saved the building, Modesto Fire officials said. Damage was estimated at $50,000, principally from the water that soaked walls and carpeting. Firefighters reported the building was surrounded by construction fencing but a back door was unlocked. A motorist called in the fire at 7:43 a.m. The restaurant at 1616 Sisk Road closed in 2009.