As a prospective hands-on self builder the two most frequent questions I am asked are:   Who is your main builder? Who will be setting out for you?   The answer to both questions is = me. I am not troubled by the intellectual or practical challenge of setting out the plan view of my house but "doing levels" remains a mystery. I have a prescribed ridge height with my planning permission and lack of gradient for the foul drain is of more concern than too much gradient.