A landowner and her neighbor owned adjacent parcels of land. The landowner hired a contractor to install an in-ground swimming pool on her land. The day after the contractor had excavated for the pool, the neighbor's storage shed, located on his property a few feet from the edge of the excavation, collapsed when the ground shifted. A riding tractor and patio furniture contained within the shed were damaged. The neighbor sued the landowner for damages. At trial, the neighbor established that the landowner's project caused the subsidence and the damage to his property. What else must the neighbor establish to prevail