5 inches and 6 inches gutters are the most common sizes installed for residential use. However, 7, and 8 inches are available although the larger sizes are more suitable for larger buildings or business properties. As far as downspouts go, they run at 2″x3″ and 3″x4″ in size or 3 or 4 inches in diameter.
Standard-sized downspouts (2″ round or 1 3/4″ x 2 3/4″ rectangular) are connected to a 2″ (diameter) round drop outlet (metal sleeve) that is inserted and sealed into the gutter. The area of a standard 2″ round hole is 3.14 square inches.
If there's a standard gutter size, it would be 5 inches for seamless gutters. That's what many residential homes have, though you can also opt for other common choices. Those can include 4-inch or 6-inch gutters or, in special cases, 7-inch gutters.
1. With your flexible tape measure, measure all the way around the outside of the downpipe horizontally to get the circumference of the pipe. 2. Then divide that measurement by 3.14 (π pi) to get the outer diameter of the pipe.
Use a minimum width of 4 in., except for canopies and small porches. The minimum ratio of depth to width should be 3 to 4 inches. Many custom shapes for gutters and downspouts are available; consult manufacturers' design manuals.
But what is the best type of downspout? The bigger the better. The larger your gutter downspout, the more water it can accommodate and efficiently dispel from your gutter system and away from your home.
It must have a minimum clear width of 200 mm with a minimum height of 20 mm. The weir edge must be installed 25 mm below the top of the fascia. A rainhead (G) provides 3.5 L/s of overflow.
A standard size downspout is 2×3. That means that is is 2 inches deep by 3 inches wide. An oversized downspout is 3×4 so it is 3 inches deep by 4 inches wide. This gives it twice the volume or carrying capacity.
The standard size for residential gutters is 5 inches, but homeowners can choose 6-inch gutters instead. While traditional 5-inch gutters are a common choice among homeowners, 6-inch gutters can hold significantly more water.
Downpipes are available in four sizes: 75mm, 87mm, 100mm and 120mm.
Sizing downpipes
Usually, the size for the largest collection area on the roof is used to size downpipes throughout. up to 50 m². Areas A and B require 74 mm diameter downpipes and Area C requires a 63 mm diameter downpipe (see Figure 2). Therefore, 74 mm downpipes are adequate for A, B and C.
Plastic pipes are the preferred drainage pipe due to its versatility and availability. It is lightweight and easy to use for installation. There are several plastic drainage pipes to serve different purposes and they come in various diameter sizes to accommodate different amounts of water.
Downspouts should be buried at least a foot deep underground. If you live in a cold climate, keep in mind that the frost line falls between 36 and 48 inches underground. In that case, you should dig down to below that depth to previent the need to thaw your gutters and downspouts during a cold snap.
The trench must be at least 10-inches-deep, but be aware that in cold-weather regions the pipe occasionally will clog with ice during periods of heavy precipitation.
On sloped land with clay-rich soil, downspouts should extend at least three feet out from the foundation. On flat land, the Association recommends 10 feet, unless the soil is very sandy, in which case the extender may need to be much longer.
Quad gutters
The slotted varieties are especially favoured because they are constructed to handle water overflow in areas with heavy rainfall. Quad gutters are generally made from galvanised, ZINCALUME® or COLORBOND® steel.
Dividing the total "effective" roof catchment area by the catchment area for the gutter selected, will give the number of downpipes required. This is not normally a whole number, so it is rounded up to the nearest whole number.
There is no such thing as a single standard. In fact, guttering sizes in the UK can vary anywhere from mini guttering, which is 75mm in diameter, all the way to industrial guttering, which is 200mm in diameter. That's a lot of sizes! That being said, there are certain common sizes depending on the gutter profile.
Shape of Gutters
Goes best with round downspouts. Round downspouts drain water more efficiently than rectangular ones.
6-inch gutters can handle almost 50% more water than 5-inch gutters. They are installed with bigger 3”x4” downspouts for better water management. 6-inch gutters are less likely to get clogged up because they can handle more water flow, and they come with a bigger outlet.
Larger, six-inch gutters are easier to clean and maintain because their mouth at the top is an inch wider, giving more space for removing debris. Since they are easier to take care of, they are also less likely to clog.
Gutter downspout sizes are 3 to 6 inches wide. The larger a gutter downspout, the more water it can drain away quickly. However, if a gutter downspout is too large, it can look unattractive. Most downspouts are rectangular, but they can also be round or square.
There's no shortage of options. Even though 68mm round and 65mm square downpipes are among the most common, most rainwater systems are available in multiple sizes. For example, this might be 75mm, 87mm, 100mm and 120mm for a certain range, with corresponding gutter sizes to match.
The typical recommendation is one downspout for every 20 to 30 feet of gutters. The next factor to take into account is the pitch of your roof, because the pitch will cause water to flow in a certain direction.