Sizing a roof water drain.
Roof leader sizing.
And 4 area handled by each drain.
This corresponds to a minimum top width of 6 inches.
But this isn t the whole story.
The use of 4 x 5 downspout outlets starts at a depth of gutter of 4 5 inches.
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.
The flow rate through vertical leaders shall not exceed that specified in table 1106 3.
2 500 4 x 7 2 9 375 sq ft 4 500 sq ft.
2 total area of roof.
The above sizing is reflected in the development of figure 4 downspout outlet sizing leader pipe sizing.
System sizing data rainfall when expressed in g p m.
Table 1106 3 vertical leader sizing for si.
Vertical leaders shall be sized based on the flow rate from horizontal gutters or the maximum flow rate through roof drains.
When sizing roof drains the limiting factor for the amount of water each drain will carry away is the size of leader therefore increasing.
3 size of leader required.
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.
Take the roof s total square footage and divide by the total square footage handled by one drain.
Rate of rainfall would.
From table a101 2 a 12 inch wide weir with a inch head carries6 460 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.
50 000 4 400 11 36.
1 inch 25 4 mm 1 gallon per minute 3 785 l m.
Section 101 5 of the ipc tells us not to reduce the pipe size in the direction of flow.
1 rate of precipitation.
Or 12 drains required.
The result is the number of drains needed.
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.
Using figure 8 the 312 g p m.
The next step is to determine each roof area that will be served by a separate leader drain pipe scupper or downspout.
Use12 ichwdex5 inch high scuppers at four locations.
The availability of 7 inch top width k style gutter has been poor in the past.
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.
