Another thing they might advise you on is the utilities. Although many people use the same lines for both the main house and their granny flats, some builders advise that they should have separate lines for gas, water, and electricity. That’s because it is easier to manage if you decide to rent the flat out, or if you are not going to use it for long periods. That’s because you can easily turn off the gas and electricity to the flat, without it affecting the main house.