Pitch or steepness also is a factor.
Roof area to gallons.
In the form below choose an area s and a rainfall amount to see how many gallons of water fell from the sky onto that area.
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.
Gutters and a downspout.
Rain barrel supplies list.
Take the dimensions of the footprint of your roof and convert them to inches.
One gallon will cover 50 square feet of foam or modified bitumen roofing concrete or bonded tar and gravel roofing.
Roof area the 3 inch rainfall will produce 18 700 gallons in one hour at the rate of 312 gallons per minute.
So a 50 x 20 roof is 600 x 240 multiply the roof dimensions by the number of inches of rainfall.
A roof of 1 200 square feet in size will collect more water than one that is 600 square feet.
The runoff for the grass portion of drainage zone a is.
Just a half inch of rain falling on a 1 000 square foot roof will yield 300 gallons of water.
The runoff q for the roof area in drainage zone a is.
You might even want to know how many baths you could get from your rainstorm.
Rainwater collection calculator in gallons.
The answer is about 623 gallons.
Or 0312 gallons per minute sq.
1 inch of rainfall in an hour will cover 1 sq ft.
Notice that even though the grass area is nearly 2x that of the roof the roof runoff is nearly 2x that of the.
Using a 10 000 sq.
Multiply across each row.
To calculate the runoff from any given rainfall.
Either way you would like to know how much rain has fallen how many gallons have come down from the skies onto your roof yard block or town.
Roof area ft 2 x precipitation amount in x 0 623 amount collected gallons easy formula to remember.
Total roof area also affects runoff.
An inch of rain is not much but it if falls in half an hour it could flood a gutter.
For all three products allow one gallon of roof coating for every 80 square feet of corrugated metal roof or 100 square feet of smooth metal roofing.
1 00 x 1 5 x 500 96 23 7 79 gallons per minute.
Highly porous concrete roofs may require more coating for proper coverage.
Converting this to gallons per minute per square foot gpm ft 2.
To a depth of 1 in 1 hour.
1 of rain on 1 000 sf roof will yield 623 gallons roof area m 2 x precipitation amount mm amount collected liters other water conservation calculators.
To get an idea how much water the roof of your own house might yield use the rainfall harvest calculator above.
0 35 x 1 5 x 900 96 23 4 91 gpm.
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.