And here’s the basement plan. I have absolutely no idea why the builder put in all those internal concrete walls (in black) when beams and pillars would have done just as well and left the space a lot more open. The concrete walls in the long (up-down) direction are especially unnecessary since that’s the direction of the joists. (Gray walls are 2×4 framing.)

I kinda hope they’re removable, since they’re really in the way. So is the drain/vent stack, which is right smack in the middle of that room (it apparently goes up right behind the first floor toilet). I’m hoping it can be relocated over next to the outside wall.

Ceiling heights are 6′ 7.5″ from concrete slab to bottom of joists. I’m pretty sure that since the house was built before 1979 we’d be grandfathered in if we wanted to make it into legally “habitable” space. We’d really like to be able to add a bedroom, but I’m not sure right now where we’d be able to fit it without major re-routing of utilities.