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