The spacing of bars in a flat slab, shall not exceed 2 times the slab thickness.
Area of Reinforcement
When the drop panels are used, the thickness of drop panel for determining area of reinforcement shall be the lesser of the following:
(a) Thickness of drop, and
(b) Thickness of slab plus one quarter the distance between edge of drop and edge of capital.
The minimum percentage of the reinforcement is same as that in solid slab i.e., 0.12 percent if HYSD bars used and 0.15 percent, if mild steel is used.
Minimum length of Reinforcement
At least 50 percent of bottom bars should be from support to support. The rest may be bent up. The minimum length of different reinforcement in flat slabs should be as shown in Fig. 16 in IS 456– 2000. If adjacent spans are not equal, the extension of the –ve reinforcement beyond each face shall be based on the longer span. All slab reinforcement should be anchored property at discontinuous edges.