Nepal, Dec. 23 -- This Christmas Day marks 21 years since the terrifying Indian Ocean tsunami. As we remember the hundreds of thousands of lives lost in this tragic event, it is also a moment to reflect on what followed. How do communities rebuild after major events such as the tsunami and other disasters like it? What were the financial and hidden costs of reconstruction?

Beyond the immediate human toll, disasters destroy hundreds of thousands of buildings each year. In 2013, Typhoon Haiyan damaged a record 1.2 million structures in the Philippines. Last year, earthquakes and cyclones damaged more than half a million buildings worldwide. For communities to rebuild their lives, these structures must be rebuilt.

While governments, non-go...