Ibc Roof Drain Sizing

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

Ibc roof drain sizing.

The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process. The result is the number of drains needed. Each vertical drain must carry 2 500 sq ft of roof area at 3 75 inches per hour of rainfall. Or less in diameter the piping will be larger in diameter than the roof drain.

1106 2 size of storm drain piping. Or 12 drains required. Roof drain connected to a 6 in. 2 500 4 x 3 75 2 344 sq ft.

Following this logic it is possible that for roof drains 6 in. P 1503 4 roof drainage. 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. Take the roof s total square footage and divide by the total square footage handled by one drain.

For example a 4 in. To convert to an area for a 4 inch per hour rainfall to enter table 1108 1 do this. 50 000 4 400 11 36. 1 inch 25 4 mm 1 inch per foot 83 3 mm m.

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. The flow rate in storm drain piping shall not exceed that specified in table 1106 2. From figure 1108 4 the 100 year 60 minute precipitation is 3 75 inches per hour. 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. 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 minimum size of any building drain serving a water closet shall be 3 inches. Vertical and horizontal storm drain piping shall be sized based on the flow rate through the roof drain.

According to the chart for 1 8 slope per 12 of pipe for 5 000 square feet of roof area with a 6 per hour of rainfall the required pipe size is 8. The result is a roof collapse. 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. Example roof plan 4 a 101 2 solution.

In total square footage covered per drain 23 14 2 880 1 920 1 440 1 150 960 720 575 480 410 360.