After a piano literally fell through a White House floor, engineers assessed the 150-year-old structure and found it was rotten and “in imminent danger of collapse.” It would have been cheaper to tear it down and build something better, maybe even on a larger tract of land. But President Harry S Truman was appalled by the symbolism. Instead, he shored up the outer walls, ripped out everything inside those walls, and had it rebuilt to “skyscraper strength.” The oldest section was “a mere shell,” with two new wings added, and concrete and steel beams replacing wooden joists. Later, Jacqueline Kennedy oversaw detailed restoration of the interior.
The White House is Mostly a Reconstruction of the Original – Marissa Fessenden, Smithsonian