How to Install a Half-Round Gutter

At the high point of the gutter's run, hold a bracket and a section of gutter against the fascia, with the gutter's outer lip just under the plane of the roof. Make a mark with a pencil for the bracket's screw hole. Use a water level to make a matching mark at the downspout end. Measure down from that mark, ½ inch for every 10 feet of run, and mark the low point. Snap a chalk line between the high and low marks, and you have your pitch.