The old adage is to measure twice. It makes no difference if you are cutting or nailing. A wrong measurement is time-consuming to correct. By watching this happen over and over and doing it ourselves, we knew it was time for a tool for keeping Girts- sidewall 2x’s evenly spaced and level, and for spacing the roof Purlins evenly also. Making sure the foundation is correct is also an old adage: start straight, end straight. If you keep all of your framing right, the finished building will be right.