Roof Drain Slope

For flat roof drainage where you place your drains scuppers and the final material of the roofing is more important.

Roof drain slope.

When the bubble on a level is about 1 4 of the way past the line it is about a 1 4 slope. Care must be given so that debris does not collect and thus cause damage. 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. Tips on calculating drain pipe slopes.

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. This may eventually cause leaks and other damage. Use the longest level possible for your application for the best accuracy. 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.

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. Increasing the angle of a flat roof will always increase the speed of water movement across the surface. Due to the gradual low slope of this type of roof rainfall will not drain as effectively. The angle is not significant enough to prevent water from pooling on the surface.