Building demolition is one of the most common activities in the construction industry. Several demolition techniques are commonly used, including mechanical demolition, deconstruction and hybrid demolition. Although deconstruction has been advocated for its environmentally friendly approaches, the cost comparison of a demolition project under different techniques is rarely researched. In this paper, the cost of a demolition project is broken down to input and output costs, which are further broken down to more countable sections. Through an empirical study in Victoria, Australia, project costs of mechanical demolition, hybrid demolition and deconstruction are investigated. It is found that deconstruction has the greatest profitability among the three techniques. Hybrid demolition, which is the actual technique adopted by the contractor, has a slightly lower profit, and mechanical demolition is the most expensive. Although deconstruction has the best overall economical performance, the small extra gain comes with increased complexity and risk that deters demolition contractors from its attempt. It is found in the paper that an optimized demolition project strategy exists between hybrid demolition and deconstruction with the greatest profitability among various building demolition techniques.