Sheet1ROOF DRAINAGE CALCULATIONSProject Name:Date:Project No.:Location:LOCAL RAINFALL INTENSITY: (From ASPE Databook or Applicable Code):Inches/HrGPM/Sq. Ft.SECONDARY DRAINS: (100 YEAR OCCURANCE, 15 MINUTE DURATION):40.042PRIMARY DRAINS: (100 YEAR OCCURANCE, 60 MINUTE DURATION):40.042DEPTH OF WATER OVER THE PRIMARY SCUPPER:2DEPTH OF WATER OVER THE SECONDARY SCUPPER:1PIPE COEFFICIENT OF ROUGHNESS (n):0.0145SLOPE OF HORIZONTAL PIPES (FOOT PER FOOT):0.01PercentageSECONDARY DRAINSPRIMARY DRAINSRoofRoofTributaryTotalRequiredSize ofSize ofWidth ofWidth ofRequiredSize ofSize ofDesignationAreaWall AreaAreaOverflowOverflowOverflowSecondaryPrimaryPrimaryPrimaryPrimary(See(Sq. Feet)(Sq. Feet)To BeDrainHorizontalVerticalScupperScupperDrainHorizontalVerticalSketch)See Note 1DrainedCapacityPipePipe(Inches)(Inches)CapacityPipepipe(Sq. Feet)(GPM)(Inches)(Inches)(GPM)(Inches)(Inches)000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000Note: Standard pipe sizes are 2,3,4,5,6,8,10,12,15,18 and 21inches. Please use these sizes on the drawings.CALCULATIONS:HORIZONTAL PIPE SIZE (FLOWING FULL): MANNING FORMULA:Q=(1.486/n)*A*R^.667*S^.5 OR DIA = 12*((GPM/448.7)(N)/(0.5*S^0.5))^0.375WHERE: Q=FLOW IN CFS; A=AREA, Sq. Feet; R = HYDRAULIC RADIUS, Feet; S = SLOPE, FT/FT; n = COEFFICIENT OF ROUGHNESSVERTICAL PIPE SIZE (FLOWING 7/24 FULL):GPM =27.8(7/24)^1.666(D)^2.667 OR DIA = 0.617(GPM)^.375PRIMARY SCUPPER:GPM = 4489.86(3.33(W*12-0.2H*12)(H*12)^1.5)OVERFLOW SCUPPER:GPM = 4489.86(3.33(W*12-0.2H*12)(H*12)^1.5)WHERE: W = WIDTH OF SCUPPER (Inches) H = HEAD (Depth) OF WATER OVER BOTTOM OF SCUPPER (Inches)2 Inches for Primary Scuppers1 Inch for Secondary or Overflow ScuppersNotes:1. Adjusted wall areas should be put into the spreadsheet as the entire square footage. This number will beadjusted by the spreadsheet to calculate only one-half of the square footage in the calculation.2. The smallest pipe size available is 4 inches in the calculation. If you have a small roof area, verify if asmaller pipe size could be used in accordance with the applicable code.

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