You should have enough gutter downspouts to effectively handle the size of your entire gutter system.
Gutter and downspout dimensions.
Size of the gutter drainage area.
Use the chart below to figure out how many extra downspouts you need.
Use this downspout extension to divert water away from the foundation or connect to drainage pipe and catch basin to control drainage.
Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area.
The flexible design easily bends and holds its shape and can be extended from 25 in.
How to figure the right downspout size.
The size of the downspout should be constant through out its length.
Gutter downspout sizes are 3 to 6 inches.
Continuing with our example in the last step we know our gutter downspout system may be subject to as much as 1 880 gallons per minute.
Downspouts are commonly 2 x 3 inches and 3 x 4 inches in size or 3 or 4 inches in diameter.
You should be able to.
Round 3 inches 706 square feet 4 inches 1 255 square feet.
Measure your gutter across the top from the back where the gutter meets the home to the outer edge.
Rectangular 2 by 3 inches 600 square feet 3 by 4 inches 1 200 square feet.
Offset of more than 10 ft 3 0 m can affect drainage capacity.
The larger a gutter downspout the more water it can drain quickly.
The most common gutter sizes are 5 inches and 6 inches although 4 inches is available as well.
Most downspouts are rectangular but they can also be round or square.
The gutter outlet capacity should suit the downspout capacity.
The sizes available in this style are 3 4 5 and 6.
But more could be.
For design purposes and aesthetics let s assume you have selected an 8 gutter.
As with gutters a downspout s capacity must match or exceed the expected runoff.
5 inch standard k style gutter shop 5 gutterbrush.
Rainfall intensity is measured in inches per hour at a 5 minute interval.
See photos below most residential gutters will measure approximately 5 inches across the top with the actual opening being approximately 4 5 inches.
Round downspouts come in various sizes and colors and mostly used with half round gutters.
One downspout is typically enough for every 20 25 feet of guttering.
The downspout size must suit.
Downspouts should be constructed with conductor heads every 40 ft 12 2 m to admit air and prevent vacuum.