House raising
House raising (house lifting, house jacking, barn jacking, building jacking) is the process of separating a building from its foundation and temporarily raising it with hydraulic screw jacks. The process is the first step in structure relocation in which the building is moved to a different location. House raising may also be a part of a renovation to build a foundation under an existing house or make a house larger by building a new floor level creating a two story house. Often employed in areas that are prone to flooding and storm damage, this process can be achieved through the use of either timber piles or helical piles. Once a house is raised and supported on cribbing, a new foundation can be constructed beneath it. After Hurricane Katrina and Hurricane Sandy large numbers of houses in parts of Louisiana, New York and New Jersey were raised to avoid future flooding.
Washington Block
The isolated pier technique uses several separate foundations, one at each of the load-bearing points underground. Thus, instead of using a single foundation that would crack as the building shifted on sandy soil, a building may be built on a much longer-lasting and sturdier foundation. The Washington Block's foundation enabled it to be built on soft, compressible soil, instead of the solid bedrock formerly seen as a requirement. This ability allowed skyscrapers to be built in places like Chicago, and many of them were.