Dear Naved,
Really disheartening to find such questions on this forum.
Please note that first, you have to do your homework, nothing comes for free.
If you are a student then ask your professors what the answer to your question is.
If you are working then first go through the structural drawings thoroughly, ask your consultant. Most of the consultants issue general RCC details wherein all such details are mentioned, if not then ask the consultant in writing what should be the lap length, where it is to be kept etc. All such details are got from the structural consultant.
All designers first make use of relevant I.S.Codes before making changes as per their design requirements. so if you want a general answer then refer the relevant IS CODES and if you want a specific answer then ask the Structural Consultant.