Silly me, assuming that the shed I'm fixing had been built plumb. But I
did find out why the sill plate was so remarkably well rotted.

The shed uses the garage as one wall. The idiot who built it managed to
miss the stud by an inch or so when locating one wall. Since the garage
wall is finished and insulated, I really didn't feel like tearing into
it just now to put in another stud--for a "rig" the plan was to put a
2x8 against the garage wall, fasten it to the sheathing with a few
toggle bolts to get a seal, then strong-tie it to the existing stud and
every other piece of structure I could find that a strong-tie would
reach, with the plan being to add the inside stud later when am doing
some repairs inside the garage (that piece of drywall does have to come
out eventually, just not today).

While it's not all that aesthetically pleasing a solution, it would
still be a _lot_ better than what had been in place, that was simply
nailed to 3/8 inch sheathing, and not even flush against it for most of
its length.

Well, I put the 2x8 in place and levelled it, and with it lined up with
the edge of the last rafter, the bottom end is sticking out two inches
past the end of the slab.

Mea culpa--I should have checked _before_ I bolted down the sill plate
(and glued and caulked). The retaining rods are stainless and I managed
to get some concrete dust or something under the nut when I was
tightenign them--getting that thing off again to redrill and reposition
it is going to be bugger-all, especially since I'm not going to get
another chance to work on it until it's all had a week to cure.

I suppose I could just cut them off and get a long bit for the SDS drill
and set some new ones.

Anyway, now I know why the frigging wall was rotting to pieces in the
first place--non-pressure-treated sill plate sticking out two inches
from the slab and a half inch above the ground.

My temptation is to just say "screw it" and finish the wall out of
plumb--it will be sloping in, not out, so the tendency will be to keep
it drier instead of wetter.