No balcony is complete without a slab, which is the part of the balcony on which you sit and stand. Balcony bases are made from a variety of materials, but when the term "slab" is used, it typically refers to the base of a balcony made of a large piece of cast concrete.
A balcony slab is typically 1 foot thick, and its surface area is in accordance with the builder's desired size of the balcony. Balcony slabs are often unfinished, resulting in a gray color, though it's possible to paint them to a color of your choosing.
Balcony slabs are made by pouring concrete into a special form made of wood or metal. When the concrete hardens adequately, the builder removes the form and is left with the large concrete slab. Because the slabs are too heavy to lift by hand, the builder uses a crane or boom stuck to lift each balcony into position on the building.
Concrete slab balconies are typically mounted to the building in a cantilever style, meaning they are attached at the wall of the building but not elsewhere. As such, each balcony juts out from the building without mounting brackets below or retaining wire above. This style of construction is safe because the balcony is secured at the wall of the building and the wall also helps hold the balcony in place.
While concrete slabs are basic, the builder typically adds accents to make the balcony functional and stylish. Building codes require balconies on apartment buildings to have railings, and railings are often made of wrought iron, wood or glass. Some apartments have concrete slab balconies outside the living room or bedroom, while others use a long balcony that is accessible through doors in each room.