[WestsideLA]

Originally Posted by ardecila

The basement isn't a requirement of a deep foundation system. You build a basement because you need the extra space, especially for things that are necessary but unattractive (parking, storage, utility stuff). A deep foundation in Chicago is usually a caisson system, and you can drill caissons from ground level just as easily as from Level -1.

This is for large commercial projects, of course. For homes, especially small ones, the need to put (shallow) foundations below the frost line at 5 feet down means you're already basically doing all the work to dig out a basement space, so you can either backfill that space after the foundations are poured and waste the effort, or pour a basement floor while you have it dug out and put it to good use.

Thanks!!