**There are two types of bars present in the slab**

**1- Main bars**

**2- Distribution bars** (bars provided against shrinkage and temperature)

**Maximum spacing Between Individual Bars**

1- The maximum diameter of the bar used in the slab should not exceed 1/8 of the total thickness of the slab.

2- For main bars, maximum spacing is restricted to 3 times effective depth or 300 mm whichever is smaller.

3- For distribution bars, the maximum spacing is specified as 5 times the effective depth or 450 mm whichever is smaller.

Hence, the diameter of the bar, the thickness of the slab, effective depth and spacing are co-related.

**Effective depth = depth of slab – clear cover- half of the diameter of the bar**

**Minimum Distance Between Individual Bars**

Minimum Distance Between Individual Bars & main reinforcing bars shall usually be not less than the greatest of the following:

The following shall apply for the spacing of bars:

1- The diameter of the bar if the diameters are equal,

2- The diameter of the larger bar if the diameters are unequal and

3- 5 mm more than the nominal maximum size of coarse aggregate.

Clear cover (Nominal Cover) shall be kept in mind while calculating the above parameters.

Source: IS-456 (2000)