How To Size Roof Storm Drains

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.

How to size roof storm drains.

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

For example a 4 in. If the area of each wall is not the same add 50 percent of the difference between the two areas. 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. Calculate total roof area.

Each 4 drain size in a 6 hourly rainfall area will accommodate drainage of 3 070 sq. 2 500 4 x 3 75 2 344 sq ft. 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. For horizontal pipes or leaders receiving two or more roof drains.

To convert to an area for a 4 inch per hour rainfall to enter table 1108 1 do this. Or less in diameter the piping will be larger in diameter than the roof drain. Each vertical drain must carry 2 500 sq ft of roof area at 3 75 inches per hour of rainfall. Determine leader or pipe size.

Calculate the total roof area by multiplying its length by width. Step by step instructions step 1. 3 size of leader required. Ipc provides four steps to size the roof drains on a building.

The four things you will need to know are. 1 rate of precipitation. 2 3 4 5 6 and 8 in. 3 size of leader required.

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. For multiple walls use 50 percent of the maximum projected area of all walls. And 4 area handled by each drain. Enter table 1108 1 until you find a diameter pipe that will carry 2 344 sq ft.

Zurn makes it easy to size roof drains. For drain areas between two opposite walls add no additional area. 1 rate of precipitation. Roof drain connected to a 6 in.

For larger roof drains the pipe may be smaller such as a 10 in. 2 total area of roof. 2 total area of roof.