Ibc Roof Drain Sizing

The international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures.

Ibc roof drain sizing.

1106 2 size of storm drain piping. P 1503 4 1 secondary emergency overflow drains or scuppers. In total square footage covered per drain 23 14 2 880 1 920 1 440 1 150 960 720 575 480 410 360. Example roof plan 4 a 101 2 solution.

The minimum size of any building drain serving a water closet shall be 3 inches. Roof drain connected to a 6 in. 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 size the vertical roof drain for the same parameters 5 000 square feet of room area and 6 per hour of rain consult table 1106 2 figure 3.

To convert to an area for a 4 inch per hour rainfall to enter table 1108 1 do this. Take the roof s total square footage and divide by the total square footage handled by one drain. P 1503 4 roof drainage. 2 500 4 x 3 75 2 344 sq ft.

Each vertical drain must carry 2 500 sq ft of roof area at 3 75 inches per hour of rainfall. Following this logic it is possible that for roof drains 6 in. For example a 4 in. From figure 1108 4 the 100 year 60 minute precipitation is 3 75 inches per hour.

The result is a roof collapse. Vertical and horizontal storm drain piping shall be sized based on the flow rate through the roof drain. Or 12 drains required. 50 000 4 400 11 36.

The maximum number of drainage fixture units connected to a given size of horizontal branch or vertical soil or waste stack shall be determined using table 710 1 2. The roof drain typically will not remove the water as fast as you may think. Each 4 drain size in a 6 hourly rainfall area will accommodate drainage of 3 070 sq. 1 inch 25 4 mm 1 inch per foot 83 3 mm m.

Roof drain vertical requirement for horizontal roof areas at various rainfall rates leader size hourly rainfall in inches pipe open 1 1 1 2 2 2 1 2 3 4 5 6 7 8 size area inches sq. The result is the number of drains needed. The flow rate in storm drain piping shall not exceed that specified in table 1106 2. Design and installation of roof drainage systems shall comply with section 1503 of this code and sections 1106 and 1108 as applicable of the international plumbing code.

The flow rate used for sizing the storm drainage piping shall be based on the maximum anticipated ponding on the roof.