Let's have a talk about bracing your sagging floors, or as the professionals call it: Deflection.
Just recently I inspected an apartment building, that had multiple braces - or jacks as people call them - present in the basement, holding up some of the floor joists.
While some braces are designed to be permanent, the ones I observed were meant to be temporary- or not for that application at all.
You see, some of those braces in that particular building were nothing but good old 2 by 4's.
They seemed to be pretty soaked, full of moisture from the damp basement. The scary part was, that they appeared to be holding up a four-story apartment building full of kids and just regular people who knew nothing about the dangers below- or the one-hundred-year-old knob-and-tube wiring next to those braces, but that is another story.
It is always a good idea for your home inspector to do a simple laser-level test on a house you are interested in buying. It can save you a lot of resources and an even bigger headache.
If you like old buildings as I do, there is a good chance that you are familiar with balloon framing, exposed knob-and-tube wiring, and sagging floors.
The good news is, anything can be fixed with enough money or knowledge, or usually both.
Deflection is no exception:
The solution to sagging floors or the damaged sills and joist ends that contribute to them often involves jacking. A common scenario is to install temporary jack posts and support beams, then permanent posts and beams over new footings.
Jacking must proceed slowly; it took a long time for your floor to sink, so you can’t push it back up quickly without causing cracks and stress in the building. As with other structural repairs, jacking must also be done appropriately. You cannot simply put a screw jack under the lowest spot and start turning. Ideally, someone with experience will assess the problem and set up the posts and any necessary beams. You can then screw the jacks up a turn or two each month. Expect some cracked plaster along the way, and aim not for perfection, but simply stability and improvement. After all, if perfectly level floors and pristine walls were important to us, we wouldn’t live in old houses, would we?
You may want to contact a structural engineer before doing any work as a precaution...