House Jacking: A Realistic View, Pt 2

House Jacking part 1 is here.

When you're in a dark crawlspace, just trying to get oriented can sometimes be quite a challenge, especially in newer or larger houses.

(I have a trick for this: I drill a tiny hole — a sixteenth or smaller — through some existing feature on the floor like a knot or a seam. Then I push a wire or coat hanger through the hole, through the insulation, and down into the basement. This way it's just a matter of finding that wire to know precisely where I am.)

Next you need to form a theory that explains whatever is happening up in the living space. If the problem is saggy joists, then this part is easy. But if the problem involves a junction of joists or a girder, it can get confusing in a hurry. Especially when your squeezed into a tight space, lying on your back, with the “insulation itch” setting in.
In my opinion, one of the most difficult situations to make sense of is the “hump in the floor”. At some point, I'll write about the Johnson House (1912) with its infamous hump that I only understood years later.

(Here's a rule of thumb: If some part of the floor is humped up, it can only be because some other part of the floor has settled/sunk.)

If you have a complex problem and have made it through to the point where you are ready to actually begin jacking, then you have earned my respect. Remember, though, to “hedge your bets” and think of ways to test/measure your progress as the lifting occurs. You may find that careful, “in progress” measurements will shoot down your theory, but that's better than the alternative, right?

One final matter that deserves candor is the danger and difficulty of deploying steel and/or hydraulic jacks to perform framing correction.

Now, if you use my method for fixing saggy joists, jacks aren't necessary. But, if you decide that your problem lies at a junction, pier, or along a foundation wall, then you're probably looking at the need for hydraulics and/or steel.

I've done many lifts where I placed a jack atop a 4×4 deck post, and though I've never had an accident, I will admit that this is probably one of the most dangerous of all your remodel maneuvers. The danger doesn't lie in the potential of the house coming down on you (unless you're thinking of removing/changing an existing stuctural support). No, the big danger is that the post and jack assembly will somehow become unstable and “blow out” with tremendous force.

Again, this has never happened to me nor have I even heard of it happening, but I know that it's possible under the right circumstances. Be careful.

Threaded steel posts are much safer, but they don't provide much lifting power.

Here's the bottom line: nearly anybody can fix a saggy joist, which is by far the most common floor problem. But if you believe your problem is something more than this, it may be time to start thinking about the pros and cons of hiring a professional.