This paper presents the analysis of intermediate and end debonding failure in slab strengthened using carbon tapes (Carbon Fiber Reinforced Polymer). The calculations are based on the more accurate method in the latest fib Bulletin 90. Consideration of additional effects based on three conditions: basic bond, bond friction and member curvature in the intermediate crack debonding analysis give the ratios ΔFfEd / ΔFfRd from 0.01 to 0.11, depending on the cross-section. For comparison in the simplified analysis of the ratio, MEd / MRd is equal 0.76. It is clearly visible the methods requiring more computational effort give lower values of element effort and allows the design to be more economical. As the strengthening fulfills the ultimate limit state, it does not meet the serviceability limit state. So the slab needs strengthening with prestressed CFRP laminates. Based on the serviceability limit state (SLS) the crack control (for quasi – permanent load combination, Mk,qp) is fulfilled, however the long-term deflection does not fulfil the required deflection. This is why 8 prestressed laminates are needed to fulfill the required deflection.