Place adjustable supports for the rain gutter in approximate position.

Use a temporary board on the roof to align the outside of the gutter with the slope of the roof.

Establish level and mark the brace. Place a second mark to establish downward slope.

The slope was arbitrarily chosen to be about 1.25 cm in 3 Meters (1/2" : 10'). The top of the sliding brace is below the mark because lowering this end lifted the control board at the high end, like a teeter totter. Adjusting this support system is easy.