How To Size Roof Storm Drains

1 4 in ft slope building storm drain 2 500 4 x 7 2 9 375 sq ft 4 500 sq ft.

How to size roof storm drains.

The sizing of the roof drainage system must consider all components. Each 4 drain size in a 6 hourly rainfall area will accommodate drainage of 3 070 sq. 1 rate of precipitation. From table a101 2 a 12 inch wide weir with a.

System sizing data rainfall when expressed in g p m. The pipe sizing is only one component. This table is based on zurn s roof drain vertical requirement for horizontal roof areas at various rainfall rates table. Can be applied to the table in figure 8 to determine the sizes of the various components of the conventional roof drainage system including roof drains vertical leaders and horizontal drainage piping.

In a roof drainage system you have many components. Determine 100 year 1 hour rainfall rate used for location of building. To convert this roof area to an area for use with table a101 2 do this. Calculate drains needed.

Size vertical storm drainage piping. Size horizontal storm drainage piping. 3 size of leader required. Take the roof s total square footage and divide by the total square footage handled by one drain.

That is what is wrong. Ipc provides four steps to size the roof drains on a building. The full flow capacity of a drain is not realized until the water reaches approximately 2 5 above the inlet in a four inch drain and 3 5 in a six inch drain. 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.

Select number of roof drains and calculate the roof area sloped to each drain. 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. Enter table a101 2 to find a length and head that will carry 4 500 sq ft or more. 2 total area of roof.

Using figure 8 the 312 g p m. Rate of rainfall would. Sizing data for conventional drainage storm drainage sizing precipitation rate inches hour based on 15 minute precipitation zurn makes it easy to size roof drains. Each scupper is draining 2 500 sq ft of roof area.

The above sizing data is offered as a guide only. The sizing of roof drains must be large enough to quickly carry away all water entering the roof drains. And 4 area handled by each drain.