Does anyone have any experience with connecting a new crawlspace to a existing block foundation? I know if they are both poured you could use rebar to connect them, or if they were both block you would key the new one into the existing, but is it possible to mix the two?

Good question, and I have no experience with it. Surely bashing a few holes in the block would allow the poured concrete to flow into the holes and lock things together. You may need to actually poke the concrete into the holes. I have read that it is important to remove all disturbed dirt when building a new foundation next to an old one. Makes good sense to me. If the block is a basement, you may need to go down to the bottom of the footer right next to it.

Like I said, we could use some more good people here in construction, automobiles too. I am doing what I can, but we could use a few more people like Tom in plumbing.