How much can you actually raise a slab?

Foam handles the common range well, roughly the first one to four inches of settlement, which covers most sunken driveways, walks, and patios. We can often do more depending on the slab and what’s under it. If a slab has dropped six or eight inches, that usually signals a bigger soil or drainage problem worth talking through before we lift, because at that point we want to be sure lifting is the right call.