Facts about slab spacing and effective depth:

Slab has two types of bar present in it-

– Main Bars

– Distribution Bars (Provided against compression and temperature)

Maximum space needed between each Steel Bars:

a) 1/8 of the total thickness of the slab is the maximum diameter of the bar used in the slab.

b) Maximum spacing for the Main bars is specified to whichever is lesser-3  times Effective Depth or 300mm.

c) In the case of Distribution bars, maximum spacing is restricted to whichever is lesser-4 times Effective Depth or 450mm.

Therefore, we can assume that, Spacing, Thickness of Slab, Diameter of bar and Effective Depth are inter-related.

We can conclude from here:

Effective Depth=Depth of Slab-Clear Cover-Half of Diameter of Bar

Minimum gapping needed between Individual Bars:

For spacing of Bars, following are applicable:

a) If diameters are equal- Diameter of the Bar

b) If diameters are unequal- Diameter of the larger Bar

c) Should exceed the nominal maximum size of coarse aggregate by 5mm.

While evaluating the above parameters, Nominal Covers should be kept in mind.