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Downspout Buying Guide: Types, Installation & More

A downspout is a drain pipe that helps carry rainwater away from your home's foundation. It is an important part of your home's landscaping and can help improve its overall appearance. 

Before your next home improvement project, be sure to review this downspout buying guide for everything you need to know about types, installation, and more.

What Are Downspouts & How Do They Work?

A downspout is defined as a vertical pipe that carries rainwater from the roofline to the ground.

The gutters are sloped towards the downspout to channel the water down. The water then flows through the downspout due to gravity and is discharged away from the foundation of your home. At the end of the downspout is usually a drainpipe that directs the run-off water with an elbow above ground or drains below ground into a drain tile. 

Downspouts come in a variety of colors and materials to match your gutters or trim. And they can be either round or rectangular. Most downspouts range in size from 2 inches to 4 inches in diameter.

Downspouts protect your home from water damage by redirecting rainwater away from the foundation. They prevent flooding in your basement or crawlspace. They reduce the amount of runoff and erosion around your home and improve the overall appearance of your home.

Types of Downspouts

There are two main types of downspouts: round and rectangular. Typically they are paired based on the style of gutters, though ultimately interchangeable. Let us look at these two types of downspouts.

Round Downspouts

Round downspouts are the standard first choice for a half round gutter system installation but are also compatible with box-style and k-style gutters There are two primary round downspout styles to consider: Plain Round or Round Corrugated both are circular in shape, however, Round Corrugated, also called Fluted Downspouts have corrugations/flutes that provide extra strength as well as conceal dents over time. 

Round downspouts are available in a range of sizes and finishes. The diameter can be 3, 4, 5, or 6" and they come in painted aluminum, mill finish aluminum, copper, galvanized, galvalume, freedom gray copper, and Rheinzink. Not every size and profile is available in all metals so be sure to check availability for the particular system you are installing. 

Rectangular Downspouts

Rectangular downspouts are typically used with k style and box style gutter systems; although they can be used with half round gutter systems. Since they are roll formed through a downspout machine they have corrugations. These corrugations strengthen the downspout and add additional rigidity. Standard and readily available sizes are 2x3, 3x4, and 4x5.

Downspouts vs. Rain Chains

There are two main types of rainwater drainage systems: downspouts and rain chains. 

Downspouts are the more traditional option, consisting of a simple pipe that directs water from the gutter to the ground. Rain chains, on the other hand, are a series of metal links or cups that funnel rainwater from the gutter to the ground. 

Unlike downspouts, rain chains do not discharge the water directly to the ground. They are usually hung from the gutter with an installation clip or kit. The water cascades down the rain chain and is discharged into a rain barrel or onto the ground.

Both rain chains and downspouts have their own advantages and disadvantages. Downspouts are more effective and can handle more rain flow than rain chains, while rain chains add more architectural appeal than downspouts. 

Rain chains are a popular alternative for homeowners to downspouts because they are easy to install and add a decorative touch to your home. However, they are not as effective as downspouts and can be problematic in areas with heavy rains. If you live in a city with light rainfall, a rain chain may be a good option for you. But if you live in an area with heavy rains, it is best to choose downspouts.

Downspout Installation Tips

Below is a step-by-step guide to installing a downspout. Downspout installation is simple. You may contact a professional installation service if you need assistance or want to ensure the job is done perfectly.

  • Step 1: Start by cleaning the gutters to ensure the downspout is properly installed and working correctly. Check the gutters are pitched toward the downspout with a chalk line.

  • Step 2: Cut a hole in the bottom of the gutter where the outlet tube is to be installed.  Hold the outlet tube to the bottom of the gutter and trace a pencil line on the bottom of the gutter that matches the profile/size of the outlet that is to be installed.  Drilling a pilot hole in the bottom of the gutter makes it easier to get the tin snips started to finish the cutting.   

  • Step 3: Install the outlet tube from the inside of the gutter.  The flanges of the outlet tube will hold the outlet from falling through the gutter.  Rivet the outlet tube to the gutter and apply sealant around the perimeter of the outlet tube.

  • Step 4: Measure the length of the overhang (soffit). Often, two elbows will be needed to bring the downspout from the eave (overhang/soffit) to the wall of the structure. And a piece of downspout may be needed between the two elbows to span the soffit.  The elbows and downspouts fit inside one another and the top/higher pieces should go inside the pieces below it to ensure water does not escape the downspout.  the pieces can be screwed or riveted together.

  • Step 5: Downspout straps will need to be secured to the wall before mounting the downspout.  Typically, two downspout straps should be used on a one story structure and three downspout straps should be used on a two story structure. Downspout straps can be screwed to the wall if there is wood, vinyl or composite siding. And lead anchors, masonry nails, or tap con screws can be used on brick and stone applications.  

  • Step 6: Install the elbows/downspout/offset pieces that are being used to span the overhang. The top piece can be riveted or screwed to the outlet tube.  Two screws or rivets will suffice in holding the pieces in place. Screw or rivet the downspout to the offset/elbow pieces.  

  • Step 7: Measure the length of the downspout. The measurement will depend on whether the system will have an elbow at the bottom or if it drains below ground.  Lengths of downspout can be cut to size using a hacksaw, a chop saw, or a pair of double cut snips. Mount the downspout to the wall by screwing or riveting the downspout to the downspout straps.

  • Step 8: Add an elbow at the bottom of the downspout to divert the water away from the foundation or install a downspout adapter to transition the downspout to the underground drain tile.

If you live in an area with heavy rains, we recommend that you install a second downspout to help prevent flooding.

Downspout Sizing

The size of the downspout must be uniform throughout the entire system. While it depends on the amount of rainfall in your area of the country, in general rules of thumb for choosing the proper size is determined by the roof square footage. Most homes use 3-inch or 4-inch diameter downspouts. The three commonly used downspout sizes are:

  1. Three-inch diameter 2x3 rectangular and 3 inch round downspouts can handle about the same amount of water flow. Typically, 3 inch downspouts can carry water from approximately 600 sq. ft. of roof area.  And at minimum there should be one downspout for every 30 ft. of gutter.

  2. Four-inch diameter 3x4 rectangular and 4 inch round downspouts can handle the water from approximately 1200 sq. ft. of roof area.

  3. Five-inch diameter 4x5 downspout and 5 inch round downspout can handle 2000 sq. ft. of roof area.

Primarily, the size of the downspout depends on the gutter system design, roof shape and pitch, and the amount of water needed to be drained. Ultimately, the size of the downspout determines how fast the water can escape making it in many cases making it more important than gutter size.  For instance, a five-inch gutter needs a three-inch downspout, and a six-inch gutter needs a four-inch downspout and so on. 

Other factors that affect the downspout size are:

  • The amount of rainfall: If you live in an area with light rainfall and few trees, you may use a smaller diameter downspout. But if you live in an area with heavy rains and lots of trees, we recommend using a larger diameter downspout to drain out the large volume of water quickly.

  • Slope, shape, and pitch factor of the roof: If your roof is sloped, you may need a larger diameter downspout to handle the increased volume of water. A roof with many hips and valleys will also require a larger diameter downspout. The steeper the pitch, the greater the volume of windblown rainwater. So, a steeper pitched roof will require a larger diameter downspout.

  • Length of the gutter run: If the gutter run is long, you may need a larger diameter downspout to prevent clogs.

  • Design of the gutter system: Simple gutter designs with few elbows can use smaller diameter downspouts. If the design is complex with many elbows, we recommend using larger-diameter downspouts.

Downspout Materials

Downspouts are made from a variety of materials, each with its own set of benefits and drawbacks. The most used materials are aluminum, vinyl, steel, and copper.

Aluminum downspouts are lightweight, durable, and inexpensive. Aluminum is the most popular material for gutters and downspouts. A vinyl downspout is easy to install and does not rust. Steel downspouts are strong and durable but may rust over time. Copper downspouts are the most expensive but are also the most durable.

Common Downspout Accessories

Special accessories are available to enhance the performance of your downspout system. A few of them are described below.

  • Splash Blocks - A splash block is a small concrete or plastic barrier placed under the downspout. The splash block is useful for directing water away from the foundation of your house and preventing erosion.

  • Flex-A-Spout- A flex-a-spout is a flexible downspout extension. It is useful for directing water around obstacles such as bushes and trees.

  • Flex-A-Elbow - As the name suggests, the flex-a-elbow refers to a flexible downspout elbow. It is useful for making tight turns around obstacles.

  • Tile Adapters - A tile adapter connects the downspout to a round drain pipe. It directs water from the downspout into the drain pipe.

  • Cleanout Grates- A cleanout grate is a small screen placed at the bottom of the downspout. It prevents leaves and other debris from clogging the downspout.

  • Rain Drains- A rain drain is a large drainage system that collects water from gutters, downspouts, and other sources. It is usually placed at the edge of a property to prevent flooding.

  • Wire Strainers - A wire strainer, like the cleanout grate, is a screen placed at the bottom of the downspout. Wire strainers are used when the gutters are not regularly cleaned.

  • Funnels & Diverters- A funnel is a wide-mouthed cone that is placed at the top of the downspout. It collects water from the gutter and directs it into the downspout. A diverter directs water away from the foundation of your house.

  • Gutter Guards- A gutter guard is a screen or mesh placed over the gutter to keep leaves and debris out. Gutter guards prevent clogs and make cleaning the gutters easier.

Downspout FAQs

Are gutter downspouts necessary?

Yes. Gutter downspouts are necessary to direct water away from your home and prevent flooding in your basement or crawlspace. They are particularly crucial if you live in an area with heavy rains.

Where do downspouts drain into?

Downspouts drain into either a splash block or a drainpipe. A splash block is a piece of concrete or plastic that directs the water away from your foundation. A drain pipe is a perforated pipe that drains the water into a drainage system.

Whats the most common downspout size?

The most common downspout size is four inches in diameter. A four-inch downspout is sufficient for most residential roof gutters.

Are larger downspouts better?

Larger downspouts can handle more water, so they are better for areas with heavy rains. They are also better for long gutter runs and complex gutter designs. 

Should I get a downspout diverter?

A downspout diverter is a device that redirects water from the downspout into a rain barrel or other container. A rain barrel collects water that is saved for later use. A downspout diverter can help you save water and money.

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