Roof Area Per Roof Drain

Step by step sizing of zurn drains step 1.

Roof area per roof drain.

The speed at which the rain collects at the drain. The number of roof drains shown should be verified with local code requirements. Calculate the total roof area by multiplying its length by width. The above result is the number of roof drains required for the building.

Divide the total roof area by the area that one leader will handle. Roof area is 300 x 500 ft. Determine rate of rainfall for this example use 4. Size downspouts to fit the gutter.

4 roof drain 3 determine your building s location on the above map to determine the approximate rainfall as measured in inches per hour. Drainage design specific to location. Calculate total roof area. 300 x 500 150 000 sq.

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. Doubling the number of downspouts halves the required capacity for each. The roof drain calculator below is based on the maximum amount of rainfall in inches per hour of the hypothetical worst storm in the past 100 years and which has a two percent chance of occurring in any given year. Calculate total roof area.

1 inch of rainfall in an hour will cover 1 sq ft. Roof area is 200 x 500 100 000 sq. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. If the result is a fraction less use the next higher number.

Required roof drainage flow rate in gallons per minute 0 0104 x rainfall rate x roof area where rainfall rate is expressed in inches per hour and roof area is given in square feet. Walls that drain onto a lower storey roof can increase the effective roof area by around 50. Converting this to gallons per minute per square foot gpm ft 2. Total roof area 500 by 200 100 000 sq.

There are 5 easy steps to figure out how many drains your commercial roofing project will need. Roof drainage systems need to be designed to cope with the rainfall intensities for the specific building location. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. Determine leader or pipe size.

Rainfall intensities vary throughout new zealand and are often very high.