Publicité
Les langues disponibles
Les langues disponibles
Roof Drain Selection Factors
Sizing:
1.) Calculate roof area (sq. ft.) to be drained.
2.) Determine the maximum hourly rainfall rate for your area. This information is
available from your local weather bureau or code authority.
3.) Select leader (drain pipe) size. In general, increasing leader size will decrease the
number of drains required.
4.) Reference leader size with hourly rainfall rate, to determine the roof area drained
by each leader (Chart B).
5.) Divide roof area (1.) by area per leader (4.) to determine the number of drains
required.
Chart A
Leader
Pipe Size
Inches
2
3
4
5
6
8
Chart A is based on Table 11-1 from the Uniform Plumbing Code (UPC) - 2006 Edition
Chart B
Pipe Size
Inches
2
3
4
5
6
8
10
12
15
Chart B is based on Table 11-2 from the Uniform Plumbing Code (UPC) - 2006 Edition
Maximum Allowable Horizontal Projected Roof Areas
Square Feet at Various Rainfall Rates
1 in./hr.
2 in./hr.
2176
1088
6440
3220
13840
6920
25120
12560
40800
20400
88000
44000
Allowable Flow (GPM) for Vertical Leaders
and Horizontal Storm Drains
Vertical
Leader
23
67
144
261
424
913
-
-
-
3 in./hr.
4 in/hr.
725
544
2147
1610
4613
3460
8373
6280
13600
10200
29333
22000
Horizontal Storm Drain / Slope
1/8"/ft.
1/4"/ft.
10
15
34
48
78
110
139
196
222
314
478
677
860
1214
1384
1953
2473
3491
2
5 in./hr.
6 in./hr.
435
1288
2768
5024
8160
17600
2
1/2"/ft.
20
68
156
278
445
956
1721
2768
4946
363
1073
2307
4187
6800
14667
Publicité
