We have expressed reservations about demolition, but if you are going to do it, do it like Alice Keller, who dismantled her existing 1300 square foot home and rebuilt her new one with the same 2x4s. According to the New York Times, "The crew left the garage and a portion of the subfloor intact and broke the concrete driveway into chunks for a back patio. A gas water heater, fiberglass insulation and windows landed at the RE Store, a local nonprofit shop that sells used or excess construction materials. The drywall, shingles and extra concrete went to a recycling center. Ms. Keller was able to reuse around 90 percent of the original house. "I just like reusing things," she said. "You can end up with something with more character."
It's called "deconstruction" and it helps reduce the 20 million tons of material that is dumped from the demolition of 245,000 houses in the US each year. The Times continues:
Using old materials for new buildings isn't a new idea. The Coliseum in Rome was used as a quarry to build St. Peter's Basilica and other Roman landmarks. In the United States, families often reused building materials to save money in the early part of the 20th century, a custom that fell out of favor as the country grew wealthier in the 1950s.
Today, according to the Building Materials Reuse Association, up to 85 percent of the average house can be recycled or reused; the hard part is harvesting the materials in a way that preserves their integrity. ::New York Times
The Times also writes ::Preparing to Deconstruct: A Primer , a short guide to who does deconstruction.