In order to strengthen the concrete structures, the use of Fiber Reinforced Polymer (FRP) composites has increased recently. Rather, numerous factors inducing the strength of the FRPs composites are unknown. The experimental investigation carried out to study the effect of Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) composites by different orientation and coverage area on flexural strength and crack propagation of the Reinforced Concrete (RC) slabs. Five different patterns followed to access the effective orientation and coverage area of the CFRP and GFRP composites. The comparison of the results shows that in the strengthening of the slab, GFRP is more effective. In all the patterns, CFRP/GFRP sheets effectively minimize the crack width.. © 2020, World Academy of Research in Science and Engineering. All rights reserved.