Retrofitting is a method of renovating/repairing and strengthening the weak structure that was affected due to the excessive load on structure during any uncertainty load like earthquake or due to end of service life of the infrastructure. The objectives of this paper are to design reinforced concrete and fiberreinforced polymer jacketing of failed columns of an existing building, after addition of two more storey in previous design and to compare suitability of before mentioned methods of retrofitting. The presented work also describes design procedure of reinforced concrete, carbon fiber reinforced polymer jacketing for strengthening existing columns. This study is fruitful to gauge suitability of the two retrofitting methods for weakened structural members. The existing buildings in Nepal designed as using Mandatory Rules of Thumb are most vulnerable types of building; to mitigate further crack in structural members with appropriate type of retrofit will be considered with proper management of construction related to post-earthquake activity. After analysis and design of existing building its extremely necessary to plan construction management for economic and safety concern. Most cases of such projects will lead improper work without proper construction management leading uneconomic and prolonging of completion of project.