A slab is a structural element made of concrete that is used to create flat horizontal surfaces such as floors, roof decks and ceilings. A slab is generally several inches thick and supported by beams, columns, walls, or the ground.

Concrete slabs can be prefabricated off-site and lowered into place or may be poured in-situ using formwork. If reinforcement is required, slabs can be pre-stressed, or the concrete can be poured over rebar positioned within the formwork.