The White House Reconstruction, also known as the Truman Reconstruction, was a comprehensive dismantling and rebuilding of the interior of the White House from 1949 to 1952. A century and a half of wartime destruction and rebuilding, hurried renovations, additions of new services, technologies, the added third floor and inadequate foundations brought the Executive Residence portion of the White House Complex to near-imminent collapse.
In 1948, architectural and engineering investigations deemed it unsafe for occupancy. President Harry S. Truman, his family, and the entire residence staff were relocated across the street to Blair House. For over three years, the White House was gutted, expanded, and rebuilt.