Q&A for How to Level an Existing House

Theoretically you can, but the concept is that if you do one side and the other later, it will put more stress on the un-leveled side. While it is possible, it is best to get the lowest side up higher first, then lift the sides that are more level. If the base plate on your kitchen is the most un-level, you would be fine starting at that point until it is brought up to rough level with the rest of the un-level areas, then proceed leveling all areas slowly.

Start at the highest point of the house, and work your way to the lowest, leveling as you go. Use a water level to determine.

Probably not very long. You may want to lay a few inches of concrete down, first. Otherwise, it's just going to sink into the floor and not support anything.

Not unless the floor boards need to be removed to access the stumps. If it's a 'jack and pack', you don't.

Depends on your tolerance, mostly for dust and falling plaster (especially lath and plaster). Under severe conditions, bits of ceiling plaster may fall as well. There is a possibility chunks of heavy crown molding may fall, especially if it has seen any (hidden) water damage. If you have high ceilings you do not want to be hit on the head with a 5 pound chunk of molding from 11 feet high. The risk is only near the sides, but you will be working in that area to fix the cracked plaster, Removing the plaster may be just enough to start an avalanche. You can minimize dust by taping plastic on the walls etc.

The posts may be different heights depending on how much the floor above them needs to be raised. Measure the height from the ground to the floor beam and cut the post to that size, then do the same for other locations.

Use a laser level that shines a 360 degree beam, hitting all the walls. A water level is not as accurate.

Use a 20-ton jack or larger. Anything less may not be strong enough to support the weight of the floor above it.