Horizontal Roof Drain Pipe Sizing

The flow rate in storm drain piping shall not exceed that specified in table 1106 2.
Horizontal roof drain pipe sizing. The pipe sizing is only one component. But this isn t the whole story. Take the roof s total square footage and divide by the total square footage handled by one drain. Vertical and horizontal storm drain piping shall be sized based on the flow rate through the roof drain.
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. Size horizontal storm drainage piping. The roof drain or gutter or drain piping or downspout leader size diameter other size constraints e g. Calculate drains needed.
The result is the number of drains needed. Storm drain pipe sizing. Horizontal drain 2 500 sq ft. This reveals that the minimum size for the leader pipe is 5.
When sizing roof drains the limiting factor for the amount of water each drain will carry away is the size of leader therefore increasing leader size decreases the number of drains required. The first step in sizing a roof drain is to calculate the surface area of the roof that the drains will be covering as well as the average hourly rainfall rate at the building location. Zurn plumbing products groupspecification drainage operation 1801 pittsburgh avenue erie pa 16502 phone 814 455 0921 fax. Enter table 1108 1 until you find a diameter pipe that will carry 2 344 sq ft.
To convert to an area for use in table 1108 2 do this. The rain storm the flow of rainwater on the roof surface the ability of the roof drain to move the water from the roof to the piping the vertical piping the horizontal piping and the connection to the point. The next step is to determine each roof area that will be served by a separate leader drain pipe scupper or downspout. This table is based on zurn s roof drain vertical requirement for horizontal roof areas at various rainfall rates table.
In a roof drainage system you have many components. A minimum 4 inch vertical drain is required. The maximum number of drainage fixture units connected to a given size of building sewer building drain or horizontal branch of the building drain shall be determined using table 710 1 1. The maximum number of drainage fixture units connected to a given size of horizontal branch or vertical soil or waste stack shall be determined using table.
Sizing a roof water drain. Designers specify compliance with bs en 12056 3 2000 that includes a calculation for the allowable capacity of the rainwater pipes. 300 x 500 150 000 sq. That is what is wrong.
Calculate total roof area. Step by step sizing of zurn drains step 1. For example in the u k. The required pipe size is 8.
2 500 4 x 3 75 2 344 sq ft enter table 1108 2 until you find a diameter pipe that will carry 2 344 sq ft.