Lifting a home requires some mechanical power in the form of a jack. Jacks use the principle of mechanical advantage to increase lifting power. when lifting a home, hydraulic bottle jacks are most commonly used, although screw jacks are also used. The number and size of the jacks is dependent on the size and configuration of the home.
Lifting a Corner
If only a portion of the house has settled, a single jack might be enough. A 12-ton hydraulic bottle jack placed on a set of beams and lifting against a beam run perpendicular to the floor joists should raise a corner or side of a house. Work slowly and lift only 1/8 inch per day to prevent cracks to drywall or plaster.
Whole House Lifts
Lifting an entire square or rectangular house requires at least four jacks. Houses of other shapes or larger homes may require more jacks. Place beams under the house perpendicular to the floor joists. Place another set of beams under these. Jacks at each end of these beams lift the house. Movers may use larger jacks but four 12-ton bottle jacks should lift most homes.
Building a Support
Bottle jacks stand about 1 foot tall and extend less than that. Often a support structure is required. Place two 4-by-4 or 6-by-6-inch beams parallel to each other about 24 inches apart. Place two more beams perpendicular to the first on top of the ends of the first beams. Continue alternating the beams until reaching the necessary height. This is called a crib. Raise the house slightly above the planned elevation with the jack and build the crib to the correct height.
Support posts with screw jacks built in are called lally columns. After a house is lifted to its new elevation the lally is placed as permanent support, if necessary, and the screws adjusted to the proper height. Place the lally so it supports a beam that runs under multiple floor joists to support a larger portion of the home. The base of the lally should rest on a portion of the foundation of the home.