How To Size Roof Storm Drains

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 size horizontal storm drainage piping size vertical storm drainage piping.

How to size roof storm drains.

3 size of leader required. 2 3 4 5 6 and 8 in. For larger roof drains the pipe may be smaller such as a 10 in. 2 500 4 x 3 75 2 344 sq ft.

For multiple walls use 50 percent of the maximum projected area of all walls. For horizontal pipes or leaders receiving two or more roof drains. For example a 4 in. 1 rate of precipitation.

Determine leader or pipe size. Calculate the total roof area by multiplying its length by width. The four things you will need to know are. Each 4 drain size in a 6 hourly rainfall area will accommodate drainage of 3 070 sq.

2 total area of roof. 2 total area of roof. Roof drain connected to a 6 in. 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.

Zurn makes it easy to size roof drains. If the area of each wall is not the same add 50 percent of the difference between the two areas. Step by step instructions step 1. And 4 area handled by each drain.

3 size of leader required. A minimum 4 inch vertical drain is required. Roof drain connected to an 8 in. 2 3 4 5 6.

Calculate total roof area. For drain areas between two opposite walls add no additional area. Or less in diameter the piping will be larger in diameter than the roof drain. 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.

1 rate of precipitation. The four things you will need to know are. 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. To convert to an area for a 4 inch per hour rainfall to enter table 1108 1 do this.

And 4 area handled by each drain. Each vertical drain must carry 2 500 sq ft of roof area at 3 75 inches per hour of rainfall. Enter table 1108 1 until you find a diameter pipe that will carry 2 344 sq ft.