It is virtually impossible for a nonprofessional to jack up his or her house. For most home renovators out there, this is like preaching to the choir: they have no desire to lift a house.
While few of us are interested in jacking up an entire house, complete with cribs, girders, timbers, and everything else you need in order to lift the entire house off the ground, there are a number of foolhardy souls among us who feel the need to jack up a portion of the house in order to insert an extra tier or beam for repairs.
Lifting Power Problems of Jacks?
The issue is not so much lifting power. Your ordinary hydraulic jack is no match for a house. Take your strongest automotive jack from the garage and this jack will crumble under the weight of a house. More precisely, it will never even begin to lift.
Nor is the issues one of jacking timbers, cribbing, microlam, or girders. Nowadays, any ordinary DIY renovator has access to contractor grade suppliers for such items.
House Jacking and Manpower
Nor is this an issue of manpower. I have seen two men jack up entire houses. The interesting thing about house jacking is that it requires no special technology. In fact, screw jacks are the main motive force behind house jacking. Hydraulic jacks are also used, and you would want at least a 20 ton jack. Because the 40 ton jack is only incrementally more expensive, go ahead and purchase it rather than the 20 ton jack. Yes, I said "purchase" because your rented hydraulic jack will be underneath the house for a very long time, running up charges.
House - Not Easy to Jack in One Piece
Here's the issue. A house is constructed of thousands of pieces of lumber, nails, screws, wire, metal, masonry, and countless other types of building materials. All of these materials are interlocked, like a jigsaw puzzle. A house does not raise or lower like a giant box. Instead, a house raises or lowers more like a giant King-sized mattress. Imagine going underneath a mattress and trying to lift any portion of it with your fist. Most of the mattress remains stock-still, completely unmoved by your efforts. Even areas of the mattress in the immediate vicinity of your hand barely moves. It is only the portion of the mattress directly above your hands that raises. So it is with a house.
Place one, two, or even five hydraulic or screw jacks in close range beneath the house, lift slowly, and the results are disappointing. First you hear the house protest with cracks as loud as rifle shots. Joists groan. Upstairs, plaster and drywall crack and crumble and fall. Yet below, there is little sign of elevation.
Moral of the story: if you plan to do any kind of raising and shoring of any portion of your house from beneath in a basement or crawl space, just keep in mind that you will not be able to influence more than a small portion. Even then, you will probably accomplish nothing more than replacing rotten timbers with new timbers or girders, and maintaining the same slant of the floors above.