The owner of this vacant building in the pictures is trying to decide whether or not to rehab the property. I’ve been developing a scope of work for him. 2/3 of the house sits on a brick basement (most houses in the area are 1910s-1920s). The front third sits on a crawlspace of sorts. In between the each of the floor joists is concrete around 2 inches thick. Now much of the concrete is falling down. What did they do and why? The floor has soft spots throughout and will have to be torn up, I’m just trying to get an idea how bad it will be when it’s torn up. Sorry the pictures are so bad, I wasn’t about to try to crawl through any closer. Thanks for any ideas!