Roof area ft 2 x precipitation amount in x 0 623 amount collected gallons easy formula to remember.
Roof area to gallons.
1 inch of rainfall in an hour will cover 1 sq ft.
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.
The collectable rainwater from the roof can be calculated in gallons using this calculator based on the rainfall and area.
To a depth of 1 in 1 hour.
Multiply across each row.
To get an idea how much water the roof of your own house might yield use the rainfall harvest calculator above.
Converting this to gallons per minute per square foot gpm ft 2.
Total roof area also affects runoff.
The answer is about 623 gallons.
Highly porous concrete roofs may require more coating for proper coverage.
The runoff for the grass portion of drainage zone a is.
A roof of 1 200 square feet in size will collect more water than one that is 600 square feet.
1 00 x 1 5 x 500 96 23 7 79 gallons per minute.
Pitch or steepness also is a factor.
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.
Notice that even though the grass area is nearly 2x that of the roof the roof runoff is nearly 2x that of the.
Rainwater collection calculator in gallons.
Using a 10 000 sq.
The total rainfall and how rapidly it falls will affect the runoff from the roof.
Rain barrel supplies list.
An inch of rain is not much but it if falls in half an hour it could flood a gutter.
To calculate the runoff from any given rainfall.
One gallon will cover 50 square feet of foam or modified bitumen roofing concrete or bonded tar and gravel roofing.
0 35 x 1 5 x 900 96 23 4 91 gpm.
Take the dimensions of the footprint of your roof and convert them to inches.
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.
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.
You might even want to know how many baths you could get from your rainstorm.
Gutters and a downspout.
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.
The runoff q for the roof area in drainage zone a is.
Or 0312 gallons per minute sq.
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.
So a 50 x 20 roof is 600 x 240 multiply the roof dimensions by the number of inches of rainfall.