This research work was done to show comparative study residential building while considering dead and live load using AAC block or fly ash and a clay brick for G+5 building was done. The use of AAC blocks offers an innovative solution to the construction industry associated with preserving environmental issues. In this work, also an attempt has been made to calculate bricks and blocks quantity per floor. The G+5 building was designed with the help of Staad pro software and the cost calculation for steel take off, cost of structure etc. was carried out. Autoclave aerated concrete (AAC) block has been found to be economical as a construction material replaced by conventional brick. After designing the structure we are found that if we used AAC block in place of conventional brick we are saving almost around 25.08 % of steel in the overall project.