Horizontal Roof Drain Pipe Sizing

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Horizontal roof drain pipe sizing.

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. 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. Sizing a roof water drain.

The pipe sizing is only one component. A minimum 4 inch vertical drain is required. The next step is to determine each roof area that will be served by a separate leader drain pipe scupper or downspout. Designers specify compliance with bs en 12056 3 2000 that includes a calculation for the allowable capacity of the rainwater pipes.

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. 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. This reveals that the minimum size for the leader pipe is 5. The sizing of the roof drainage system must consider all components.

To convert to an area for use in table 1108 2 do this. Size horizontal storm drainage piping. 300 x 500 150 000 sq. Horizontal drain 2 500 sq ft.

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. Take the roof s total square footage and divide by the total square footage handled by one drain. This table is based on zurn s roof drain vertical requirement for horizontal roof areas at various rainfall rates table. Roof area is 300 x 500 ft.

Storm drain pipe sizing. For example in the u k. Vertical and horizontal storm drain piping shall be sized based on the flow rate through the roof drain. In a roof drainage system you have many components.

Zurn plumbing products groupspecification drainage operation 1801 pittsburgh avenue erie pa 16502 phone 814 455 0921 fax. The result is the number of drains needed. 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. But this isn t the whole story.

The roof drain or gutter or drain piping or downspout leader size diameter other size constraints e g. Calculate total roof area. The above sizing data is offered as a guide only. Enter table 1108 1 until you find a diameter pipe that will carry 2 344 sq ft.

The flow rate in storm drain piping shall not exceed that specified in table 1106 2.