Workers were scheduled to finish jacking the steel-pipe pinnacle atop the world’s tallest buildng on Jan. 10, marking the Burj Dubai’s topping out. The skyscraper’s curtain wall is 90% complete. But because of interior design changes, tower construction is not likely to be done until September, says Kyung-Jun Kim, project director for Samsung Corp. Crews jacked the pinnacle from within the structural steel spire that tops the reinforced concrete frame. The owner, Emaar Properties PJSC, still will not reveal the tower’s final height. However, project sources confirm the building is taller than 800 meters.