In most cases where a building permit involves either a new house or enlarged structure, the local Building and/or Zoning Departments will require a site plan to be certified by a Registered Land Surveyor and/or Civil Engineer to insure that the structure conforms to local regulations.
These regulation may include minimum front, side and rear yard setbacks or maximum permissible lot coverage.
In cases where a septic system is being designed by a Registered Civil Engineer, property line setbacks and minimum allowable clearances from foundations and swimming pools must also be certified.