Roof Leader Sizing

Smacna s new downspout and gutter sizing calculator enables the user to manually enter the design area of the roof or use the design area wizard for the calculation.

Roof leader sizing.

Vertical leaders shall be sized based on the flow rate from horizontal gutters or the maximum flow rate through roof drains. The flow rate through vertical leaders shall not exceed that specified in table 1106 3. 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. And 4 area handled by each drain.

1 rate of precipitation. 3 size of leader required. The four things you will need to know are. When sizing roof drains the limiting factor for the amount of water each drain will carry away is the size of leader therefore increasing.

Take the roof s total square footage and divide by the total square footage handled by one drain. The availability of 7 inch top width k style gutter has been poor in the past. From table a101 2 a 12 inch wide weir with a inch head carries6 460 sq ft. This reveals that the minimum size for the leader pipe is 5.

Sizing a roof water drain. 1 inch 25 4 mm 1 gallon per minute 3 785 l m. 2 500 4 x 7 2 9 375 sq ft 4 500 sq ft. 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.

2 total area of roof. Rate of rainfall would. Table 1106 3 vertical leader sizing for si. Use12 ichwdex5 inch high scuppers at four locations.

Section 101 5 of the ipc tells us not to reduce the pipe size in the direction of flow. System sizing data rainfall when expressed in g p m. Or 12 drains required. Zurn makes it easy to size roof drains.

50 000 4 400 11 36. The result is the number of drains needed. But this isn t the whole story. The first step in sizing a roof drain is to calculate the surface area of the roof that the drains will be covering as well as the average hourly rainfall rate at the building location.

The use of 4 x 5 downspout outlets starts at a depth of gutter of 4 5 inches. Enter table a101 2 to find a length and head that will carry 4 500 sq ft or more. This wizard makes it easy to calculate the roof design area by providing various shape calculations and the calculation for vertical walls area per international plumbing code ipc. This corresponds to a minimum top width of 6 inches.