We're planning to gut and rebuild my in-laws bathroom this summer, which will include rebuilding the old back porch so we can expand into the space (the basement actually extends 8 feet out past the back wall of the house).
Unfortunately, water damage had rotted away the two main support beams at some point, and my father-in-law cobbled together temporary supports out of whatever boards he had on hand. So, I need to jack the house up on that end and replace those beams properly before I can replace the rotted floor joists too.
Because of the missing support, the back wall of the house has dropped a little over an inch. The rest of the floor is surprisingly level, considering the house is 100 years old. It's only the last two joist bays that have sagged.
So, I need to jack the floor back to level and install new beams. But, I thought I heard somewhere you should jack a house slowly to avoid cracking plaster and whatnot (though it's already filled with cracks and crumbling off the walls).
Can someone tell me how slowly I should raise the floor that 1+ inch?
Also, I'll need to purchase a jack for this project. What capacity would generally be needed to lift a one-story house?
Thanks,
Anthony