Slab isconsidered as a very important structural elements. The slabs are generally functioned to minimize the weight coming normal to its plane. In general practise, the weight/load exerted on a beam by a slab is considered in the analysis without considering slab stiffness. In our study we will consider a G+4 L shapestructureconsidering case with and without consideration of slab stiffnessusing analysis toolSTAAD.ProThis software is capable to apply gravity and seismic loads. Shear force, storey displacements, axial force, bending moment and support reactions are considered to prepare comparative study to present the effect of slab stiffness. The results shows that there is a good reduction in forces, bending moment which will reduce reinforcement requirement and displacement of the storey due to consideration of slab stiffness. Alsovisible reduction is seen in case offorces and bending moment at supports. The slab stiffness results in reduction in reinforcement requirement and providing proper stability to the building frame. In present work approximately 20% lesser reinforcement is required when stiffness of slab is taken into account in the analysis resulting in an economical design.