Here's a not-very-good and definitely not-to-scale drawing of the back third of the house. Each third rests on its own foundation walls and is reasonably independent structurally, except of course for the fact that everything is nailed to everything else. The crosshatched regions represent the brick and sandstone foundation, which is about 2/3 below and 1/3 above grade. Floor joists run east-west (right to left) across this drawing; total width of the house is about 25 feet.

In the basement, each joist spans about half of the distance, resting on the central beam on one side and nailed to the ledger on the exterior wall. The central beam (which comprises 4 2 x 10s) is supported at its half-span with a brick column. It can carry a lot of weight, but notice that structural wall on the first floor is not directly above this beam. In the original design, this was not a problem since the load from the second floor was distributed over many joists on the first.

The location of the second floor and attic floor joists is mostly guesswork; I haven't ripped up enough flooring to know for sure how they are laid out. We can assume they also run east-west (right-left). Identification of one second floor wall as a partition wall and the other as structural is guesswork.

Here's a detail of just the first floor. During the 1970s renovation, the load-bearing wall was removed and replaced with a doubled 2 x 10 beam. The beam itself was probably adequate for the span (12 feet); the problem was with how the beam was supported.

At the north (interior) end, the beam was supported by a doubled 2x4. On the other side the beam was supported by a single 2x4. These posts rested on the kitchen's subflooring rather than running all the way down to a footer in the basement. This meant that very high point loads were applied to two spots on the kitchen floor that weren't designed to take the weight.

This is the kitchen after I took down some of the false ceiling but before any of the really serious work got started. The ceiling was lowered as part of the renovation, partially to hide the height of the beam and partially because, well, it was the 1970s. This picture is taken from the east side of the room looking west, i.e. 90 degrees off from the drawings above.

No one has an good explanation for all of the doors. The little alcove on the right has 4 doorways, two of which still have doors on them. It's an appendix-like structure now that the wall between the two halves of the kitchen is gone.

Yes that is an outdoor light fixture. It has since been banished.

If you look carefully at the close up, you can see the beam in the holes in the ceiling. The north post is embedded in the drywall between the smoke detector and the kitchen island.

This is getting into close-up overkill. I'm surprised you can't see the 2 x 4 post getting crushed under the load at the point of contact, which is evident when viewed live.

Ok you've definitely seen enough of this end!

Here's the south post. Unlike the north post, which is simply supported, the south post appeared to be just toenailed to its post. When I exposed this beam, it scared me so much that I went out the same day to the Home Despot and bought a jackscrew which is shown installed in this picture. Toenailing is a pretty scary means of load transfer. Later, I found out that there were six additional nails driven through the 2 x 4 post into the end of the beam, which makes this a little less inexcusable. But a single 2 x 4 is still inadequate support, even before one starts asking questions about how the posts themselves were supported.

Close-up of the south post with my temporary shoring.

Basement pre-construction. Notice the forest of jackscrews, and the big central beam. You can probably see asbestos fibers if you look hard enough.

Another view of the basement, just to convince those of you who have visited us that we really did clean up the basement. I know this is hard to believe.

These cabinets really helped with the clean-up. They were $70 and $100, from a used office furniture place in Cleveland. As they say in Boston, whatta bahgan.

We got some used Steelcase metal shelves also. ($100/ea; you pay extra for the Steelcase name.) The furniture place had about 90 of these, all in identical shades of taupe.