Increasing the angle of a flat roof will always increase the speed of water movement across the surface.
Roof drain slope.
For flat roof drainage where you place your drains scuppers and the final material of the roofing is more important.
Since the pitch of the roof is lower it can act as a catch all for tree limbs and other debris.
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.
The angle is not significant enough to prevent water from pooling on the surface.
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.
Roof drains for flat or low slope roofs come in a few standard types.
Tips on calculating drain pipe slopes.
Care must be given so that debris does not collect and thus cause damage.
Use the longest level possible for your application for the best accuracy.
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.