Fiber reinforced polymer jackets (FRP sheets) offer great advantages as confining devices of damaged or substandard reinforced concrete (r.c.) members and are already used extensively as local interventions in seismic rehabilitation of existing construction. The design issues and detailing rules related to this seismic repair/strengthening technique are explored by evaluating systematically the various mechanisms of resistance of the upgraded member and the jacket contribution. These include flexure, shear, lap-splice capacity, plastic hinge behavior, displacement capacity and jacket strain capacity associated with embedded bar buckling. A database of published experiments on r.c. beam/columns, tested under cyclic loading after being jacketed by FRPs was used as a point of reference in assessing the detailing rules and in calibrating design lower bound expressions. Criteria that should be considered for the upgrade design strategy in order to control the deformation demand of the structure when FRP jackets are used are also discussed in the paper.