I noticed this before, and now have a mind to do something about it:
There are a number of pilings in the interior foundation of my 98 year
old 2 story 1925 square foot house. One of them doesn't reach the base
and is suspended above it by about an inch. There's an interior door
downstairs that has been giving me problems. Occasionally, it won't
close and I sand off some of the top of the door with my belt sander. I
did that around 2 months ago and lately, the door is sticking again.
WTF. Well, I surmised that this door just might be close to the
suspended piling, and going under the house a few days ago, sure enough,
that piling is right under that door!
So, I figure I should lift up the house a bit with house jacks just on
either side of the piling and slip a solid piece of hardwood between the
bottom of the piling and the top of the base. Then lower the jacks so
the piling is taking some weight. How much weight, I guess I can't
really determine, but hopefully somewhere not far off from what it
should be supporting.
I borrowed a couple of 20 ton house jacks from my local tool lending
library and the guy said I should probably dig out the old piling base
and pour a more substantial one, maybe 2+ feet square. He said the
piling has sunk because of puddling in the past. I said, if what I'm
doing doesn't work I can always do that and borrowed the jacks anyway. I
don't believe that any puddling has happened under there for decades.
I'm wondering just how much I want to lift the beam running above that
piling before slipping in a board. The guy said I'll start to hear
creaking/groaning from the wood and I can determine from that just how
much to crank the jacks. I'm wondering if I should think in terms of
raising the beam, say, 1/4 inch before shoving the shim-board