4 ft 2.
Gallons per square foot of roof.
5 ft 2.
Code to add this calci to your website.
So a 50 x 20 roof is 600 x 240 multiply the roof dimensions by the number of inches of rainfall.
For example a 3 inch per hour rainfall will build up to a 3 inch depth on a flat roof in one hour at the rate of 1 87 gallons per hour sq.
Roof area square feet per linear ft of gutter underneath.
Up to 6 12 7 12 8 12.
Or 0312 gallons per minute sq.
To calculate the runoff from any given rainfall.
Rainwater can be collected from the roofs using the rain water harvesting method.
1 us gallon 231 cubic inches.
To a depth of 1 in 1 hour.
Take a guess what is the volume of water that runs off a 1 000 square foot roof during a 1 rain storm.
Sq ft safe for maximum rainfall reduce by 10 per 90 degree turn.
Of water 231 sq in.
Where rainfall rate is expressed in inches per hour and roof area is given in square feet.
Converting this to gallons per minute per square foot gpm ft 2.
Using a 10 000 sq.
The collectable rainwater from the roof can be calculated in gallons using this calculator based on the rainfall and area.
Of water in a gallon 0 623 gallons per hour.
1 inch of rainfall in an hour will cover 1 sq ft.
Roof area the 3 inch rainfall will produce 18 700 gallons in one hour at the rate of 312 gallons per minute.