4 Roof Drain Capacity

Roof drains zurn plumbing products groupspecification drainage operation 1801 pittsburgh avenue erie pa 16502 phone 814 455 0921 fax.

4 roof drain capacity. Increasing from one downspout to two doubles the capacity of a gutter to handle runoff without overflowing. 2 total area of roof. Each 4 drain size in a 6 hourly rainfall area will accommodate drainage of 3 070 sq. In addition to the primary roof drains there will also be overflow drains which are used for redundancy and sized in the same manner.

Take the roof s total square footage and divide by the total square footage handled by one drain. Zurn makes it easy to size roof drains. The distinguishing feature of a siphonic roof drain is the air baffle. Roof area the locale s rainfall intensity and gutter capacity determine how.

This air baffle is engineered and tested to prevent air from entering the piping system at peak flows. 3 size of leader required. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. Other than the baffle a siphonic roof drain has the same features as a traditional roof drain including a.

The result is the number of drains needed. As we will see in steps 3 4 the size of the roof drain lines is dependent on the square feet of the roof area being served by each roof drain. 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. Calculate drains needed.

4 select a reference of a roof drain size with hourly rainfall together with the roof area square footage you have estimated and then determine from the chart below how many roof drains you require. Unfortunately recommendations aren t that straightforward because you also need to account for water pressure material friction and more. The four things you will need to know are. Roof drainage capacity for other roof drain pipe or leader diameters.

Zurn engineered water solutions is a recognized leader in commercial municipal and industrial markets. Step 4 size downspouts to fit the gutter. This table is based on zurn s roof drain vertical requirement for horizontal roof areas at various rainfall rates table. A siphonic roof drain looks much like a traditional roof drain.

The above sizing data is offered as a guide only. These drains are distinguished by having higher rims. Dropping from the 5 drain in the table to a 4 drain cuts the serviced or drainable roof area to about 0 55 x the roof areas shown in the table.