Slope Factor & Depth Factor – Canada

Illustration of slope spans for roofs

Slope Factor and Depth Factor Table
Slope 2.5:12 3:12 3.5:12 4:12 4.5:12 5:12 6:12 7:12 8:12 9:12 10:12 11:12 12:12
Slope Factor 1.021 1.031 1.042 1.054 1.068 1.083 1.118 1.158 1.202 1.250 1.302 1.357 1.414
Depth
Factor
9-1/2″ 2″ 2-3/8″ 2-7/8″ 3-1/4″ 3-5/8″ 4″ 4-3/4″ 5-5/8″ 6-3/8″ 7-1/4″ 8″ 8-3/4″ 9-1/2″
11-7/8″ 2-1/2″ 3″ 3-1/2″ 4″ 4-1/2″ 5″ 6″ 7″ 8″ 9″ 10″ 11″ 11-7/8″
14″ 3″ 3-1/2″ 4-1/8″ 4-3/4″ 5-1/4″ 5-7/8″ 7″ 8-1/4″ 9-3/8 10-1/2″ 11-3/4″ 12-7/8″ 14″
16″ 3-3/8″ 4″ 4-3/4″ 5-3/8″ 6″ 6-3/4″ 8″ 9-3/8″ 10-3/4″ 12″ 13-3/8″ 14-3/4″ 16″
18″ 3-3/4″ 4-1/2″ 5-1/4″ 6″ 6-3/4″ 7-1/2″ 9″ 10-1/2″ 12″ 13-1/2″ 15″ 16-1/2″ 18″
20″ 4-1/4″ 5″ 5-7/8″ 6-3/4″ 7-1/2″ 8-3/8″ 10″ 11-3/4″ 13-3/8″ 15″ 16-3/4″ 18-3/8″ 20″
22″ 4-5/8″ 5-1/2″ 6-1/2″ 7-3/8″ 8-1/4″ 9-1/4″ 11″ 12-7/8″ 14-3/4″ 16-1/2″ 18-3/8″ 20-1/4″ 22″
24″ 5″ 6″ 7″ 8″ 9″ 10″ 12″ 14″ 16″ 18″ 20″ 22″ 24″