I have an early 1900’s ballon framed house that clearly had some DIY work a long time ago that wasn’t done very well.  The crawl space was dug out to make room for the water heater and boiler and a concrete wall and floor were poored all around the dug out area.  At some point, several of the longest sections of wall have cracked and bulged inward, likely from lateral tension, but possibly due to some minimal and distant seismic activity.

I’ve measured over time and don’t see any movement in the cracked walls, but I’d still like to replace them at some point and figure that at worst, I can’t be doing any harm.  To be clear, these aren’t the foundation walls, but walls that were built in the middle of the crawl space, that run the width of the house.  I’d plan on replacing two sections that have cracked.  One section was replaced with a reinforced pour wall before I moved in and I would want to tie into that wall.

I’ve done some reading and it looks like a poured concrete wall with rebar makes sense.  I’m wondering about any kind of drainage or insulation that I would do during this process.  The crawl space is currently vented, but does not have any mold or moisture issues resulting in rot.  Eventually, I plan on putting a vapor barrier down over the soil too.

Any thoughts/advice is welcome.