The downspout size must suit the bottom width of the gutter.
Gutter length per downspout.
The larger a gutter downspout the more water it can drain quickly.
Increasing the pitch increases a gutter s handling capacity but the gutter may look askew over a long run.
Size downspouts to fit the gutter.
The above recommendations assume that you have properly sized downspouts every 40 feet.
The gutter outlet capacity should suit the downspout capacity.
Design of roof drainage systems.
Please lower the maximum spacing between downspouts to see this effect.
The capacity of a sloped rectangular gutter may be approximated by using a gutter cross section area not less than that of a semicircular gutter and a depth to width ratio of at least 0 75.
You can t do the math like that.
For most homes this means installing spouts at either end of a gutter section.
For example adding one 4 inch round downspout will increase the gutter capacity by 1 255 square feet and one 3 inch round downspout would increase capacity by 706 square feet.
15 m is a practical maximum gutter length to be served by a downspout.
The standard is about inch per 10 feet.
If we have to sum it up in a single rule gutters need a downspout around every 30 to 40 feet.
As with gutters a downspout s capacity must match or exceed the expected runoff.
Gutter downspout sizes are 3 to 6 inches.
I m not sure what the answer is but i know you can t do it per foot of gutter.
However too large a gutter downspout can look unattractive.
Offset of more than 10 ft 3 0 m can affect drainage capacity.
The gutter and downspout size required is highly dependent on the amount of gutter and the spacing of the downspouts.
A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour.
Adding additional downspouts will require less gutter and downspout volume resulting in smaller gutters downspouts.
Downspouts should be constructed with conductor heads every 40 ft 12 2 m to admit air and prevent vacuum.
To limit the effects of thermal expansion in gutters 50 ft.
Doubling the number of downspouts halves the required capacity for each.
Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.
The standard is about inch per 10 feet.
Most downspouts are rectangular but they can also be round or square.
The above recommendations assume that you have properly sized downspouts every 40 feet.
Increasing the pitch increases a gutter s handling capacity but the gutter may look askew over a long run.
