Hey Sasivardhan,

See this thing totally depends on you but logically it's not the best option to go for pursuing B.Arch after B.Tech. But M.Arch sounds reasonable. If you're a civil engineer, and then later if you join Architecture, you'll be like the most amazing Architect ever, trust me. But, 4+5 years in studying? When will you settle down with a job? You should do your higher studies on architecture, not the bachelors. 

Hope that helps

all the best