Basics in Building Construction

Building Components And Types

Lesson 21 : Upper Floors

Flat-Slab Flooring

A flat slab is a typical type of construction in which a reinforced slab is built monolithically with the supporting columns and is reinforced in two or more directions, without any provision of beams. The flat slab thus transfers the load directly to the supporting columns suitably spaced below the slab (figure 5). Because of exclusion of beam system in this type of construction, a plain ceiling is obtained, thus giving attractive appearance from architectural point of view. The plain ceiling diffuses the light better and is considered, less vulnerable in case of fire than the usual beam slab construction. Concrete is more logically used in this type of construction, and hence in case of large spans and heavy load, the total cost is considerably less.

The slab in a flat slab construction may be either with drop or without drop. Drop is that part of the slab around the column which is of greater thickness than the rest of the slab. Reinforcement in the slab can be arranged either in two – way system or in four – way system. Two – way system of reinforcement is commonly adopted for slab subjected to ordinary loading conditions. Figure 5 a,b shows details of reinforcement in the slab along two directions, in the two – ways system.