3 inch hr.
Roof area per roof drain.
Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.
This should be considered when connecting gutters and downspouts.
For a 4 hourly rainfall and 4 leader each drain can handle 4 600 sq.
Calculate the total roof area by multiplying its length by width.
It is important to remember that no roof area should ever have less than two roof drains.
Divided by 3 460 sq.
Therefore the 100 000 sq.
A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour.
Determine leader or pipe size.
Pipe cross section drainage area.
Equals 32 6 or 33 drains required.
Flat roof drainage capacity of a single drain pipe or leader.
Roof pitch is a determining factor for cost of the roof as well as the roof area and the type of materials used.
Rainfall intensity should always be checked with the local authorities.
Roof pitch affects the actual area of the roof.
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.
Calculate total roof area.
2 inch hr.
Number of roof leaders required is 29 100 000 sq.
When placing roof drains it is good design practice to locate the drains no more than 50 feet from the roof perimeter nor more than 100feet apart.
The table is based on rainfall intensity 100 mm per hour 4 inches per hour.
Outside of the u s a degree angle is typically used.
Gutters and downspouts are vulnerable for obstructions caused branches and leafs from surrounding trees and similar.
1 inch hr.
Maximum horizontal projected roof area that can be drained in square feet.
Divided by the 4 600 sq.
Each 4 drain size in a 6 hourly rainfall area will accommodate drainage of 3 070 sq.
Size and placement of rooftop equipment may necessitate additional roof drains.
Area roof will require 100 000 3070 32 5 or 33 roof drains for ideal drainage.
6 inch hr.
Determine rate of rainfall for this example use 4.
It affects walkability as well as drainage and roofs in areas of high rain or snowfall tend to have steeper pitches.
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.
There are 5 easy steps to figure out how many drains your commercial roofing project will need.
Total roof area 500 by 200 100 000 sq.
Below to obtain roof area that can be handled by each leader.
5 inch hr.
For instance a 7 12 roof pitch means that the roof rises 7 inches for every 12 horizontal inches.
Rainfall rate inches per hour.
Ft therefore 29 roof drains would be required.
4 inch hr.
After studying building plan and physical arrangement assume that 6 leaders are.
