Roof Drain Slope

The angle is not significant enough to prevent water from pooling on the surface.

Roof drain slope. According to the chart for 1 8 slope per 12 of pipe for 5 000 square feet of roof area with a 6 per hour of rainfall the required pipe size is 8. The best type for the application depends on several factors such as the size and slope of the roof the desired appearance and how much regular maintenance the drain system might need. When the bubble on a level is about 1 4 of the way past the line it is about a 1 4 slope. For flat roof drainage where you place your drains scuppers and the final material of the roofing is more important.

The roof pitch or slope factors for roof pitch are used to multiply or increase the rainfall rate if we are draining a sloped roof the roof drain or gutter or drain piping or downspout leader size diameter other size constraints e g. Increasing the angle of a flat roof will always increase the speed of water movement across the surface. This may eventually cause leaks and other damage. To size the vertical roof drain for the same parameters 5 000 square feet of room area and 6 per hour of rain consult table 1106 2 figure 3.

Same logic with 1 8 slope 1 16 slope etc. Care must be given so that debris does not collect and thus cause damage. Since the pitch of the roof is lower it can act as a catch all for tree limbs and other debris. Tips on calculating drain pipe slopes.