Roof Leader Sizing

System sizing data rainfall when expressed in g p m.

Roof leader sizing.

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. 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. When sizing roof drains the limiting factor for the amount of water each drain will carry away is the size of leader therefore increasing. Sizing a roof water drain.

Table 1106 3 vertical leader sizing for si. 1 rate of precipitation. The use of 4 x 5 downspout outlets starts at a depth of gutter of 4 5 inches. Rate of rainfall would.

But this isn t the whole story. 2 total area of roof. Or 12 drains required. From table a101 2 a 12 inch wide weir with a inch head carries6 460 sq ft.

3 size of leader required. The result is the number of drains needed. Section 101 5 of the ipc tells us not to reduce the pipe size in the direction of flow. 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.

This corresponds to a minimum top width of 6 inches. The availability of 7 inch top width k style gutter has been poor in the past. 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. Take the roof s total square footage and divide by the total square footage handled by one drain.

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. 1 inch 25 4 mm 1 gallon per minute 3 785 l m. Using figure 8 the 312 g p m.

And 4 area handled by each drain. The four things you will need to know are. This reveals that the minimum size for the leader pipe is 5. 2 500 4 x 7 2 9 375 sq ft 4 500 sq ft.

The above sizing is reflected in the development of figure 4 downspout outlet sizing leader pipe sizing. The next step is to determine each roof area that will be served by a separate leader drain pipe scupper or downspout. Zurn makes it easy to size roof drains. Enter table a101 2 to find a length and head that will carry 4 500 sq ft or more.