Random spacing method for 3Tab shingles
Cut half a tab from the 1st starter and nail down to the drip edge. Starters must be overhanged about 1 cm over the drip edge and sealed with mastic.
Random spacing can be achieved by removing different amounts from the rake tab of succeeding courses compared to classic installation method where there is removed ½ a tab.
You have to follow these general rules:
1. The width of any rake tab should be at least ¼ a tab.
2. Cutout centerlines of any course should be located at least ¼ a tab laterally from the cutout centre line in both the course above and the course below.
3. The rake tab widths should not repeat closely enough to cause the eye to follow a cutout alignment.