How To Size Roof Storm Drains

The above sizing data is offered as a guide only.

How to size roof storm drains.

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. 1 rate of precipitation. Roof drainage 2016 05 11 plumbing advanced drainage systems sizing a gravity pipe work water surface pros for storm sewers sizing a gravity pipe work four s to sizing roof drains c1scapacities of sewer pipespipe sizing charts tables energy modelsdrain and sewer pipe size home owners workfour s to sizing roof drains c1scapacities of sewer. The pipe sizing is only one component.

From table a101 2 a 12 inch wide weir with a. Ipc provides four steps to size the roof drains on a building. The four things you will need to know are. Each scupper is draining 2 500 sq ft of roof area.

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. Rate of rainfall would. 2 total area of roof. Calculate drains needed.

Take the roof s total square footage and divide by the total square footage handled by one drain. The sizing of the roof drainage system must consider all components. This table is based on zurn s roof drain vertical requirement for horizontal roof areas at various rainfall rates table. The sizing of roof drains must be large enough to quickly carry away all water entering the roof drains.

System sizing data rainfall when expressed in g p m. Each 4 drain size in a 6 hourly rainfall area will accommodate drainage of 3 070 sq. And 4 area handled by each drain. To convert this roof area to an area for use with table a101 2 do this.

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. 3 size of leader required. Size horizontal storm drainage piping. 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.

Enter table a101 2 to find a length and head that will carry 4 500 sq ft or more. The result is the number of drains needed. 1 4 in ft slope building storm drain 2 500 4 x 7 2 9 375 sq ft 4 500 sq ft. Determine 100 year 1 hour rainfall rate used for location of building.

Select number of roof drains and calculate the roof area sloped to each drain. 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. Using figure 8 the 312 g p m.