A slab is a flat concrete platform forming a floor or foundation. It is one of the most common structural elements in construction. A slab-on-grade sits directly on the ground. A suspended slab is supported by beams or walls. A post-tensioned slab uses steel tendons to compress the concrete and reduce cracking. A waffle slab has a grid of ribs that reduces weight. Each type has its own application. The slab is the surface we walk on. It is also the structure that carries the load.

Slabs are reinforced with rebar or mesh. The reinforcement carries the tensile forces. The concrete carries the compressive forces. The slab must be thick enough to carry the load and stiff enough to prevent deflection. The slab must be supported by a compacted base. The base must be free of organic matter and soft spots. A slab on a poor base will crack and settle. The slab must be cured properly. Curing keeps the concrete moist and allows it to gain strength. A slab that dries too fast will crack.

Slabs are used in every type of building. A house has a slab floor. A warehouse has a slab floor. A parking garage has a slab floor. A bridge has a slab deck. The slab is a simple element. It is also a versatile one. It can be finished in many ways. It can be polished, stained, stamped, or covered. It can be insulated, heated, or cooled. The slab is the foundation of the interior. It is the ground we build on. It is the floor we stand on.