All downspouts and rain gutters are the same, right? Not quite. If you’re getting new downspouts, you need to match them to your gutters so that they fit. Here’s a guide on how to choose the right gutter downspout size.
Why Downspout Sizes Matter
Don’t underestimate the importance of choosing the right gutter downspout. A good fit means a watertight seal, which will allow rainwater to flow naturally through your downspouts and harmlessly into your yard or drainage structure.
Conversely, a bad fit creates leaks that put all that water where you don’t want it. Excessive water seeping into the foundation can lead to costly damage and potential structural issues. In the worst-case scenario, an incorrect downspout and gutter size can even lead to health hazards.
Here are some of the problems that homes with incorrect downspout and gutter systems may face:
- Wall damage
- Foundation damage
- Basement flooding
- Fire hazards
- Reduced gutter and downspout functionality
- Landscaping damage
- Ice dams
- Roof and fascia board damage
- Animal infestation
- Aesthetic damage
The size of the downspout determines how efficiently rainwater is drained away from your home’s foundation.
Best Downspout Size and Shape Based on Gutter Type
There are a few types of downspouts available on the market, each with its own unique features and benefits. Here are the most common types of downspouts:
- K-style downspouts: Usually sized 2×3 or 3×4 inches; suitable for K-style gutters (see below)
- Rectangular downspouts: Usually sized 2×3, 3×4, or 4×5 inches; also suitable for K-style gutters
- Round downspouts: Usually sized between 3 and 6 inches; suitable for half-round gutters
Note: You may also need a downspout adapter if you’re going to connect your downspout to a downspout extension or a pipe.
When you’re buying a downspout, make sure you have the right gutter shape and size first. The most common gutter types and sizes include:
- K-style gutters: K-style gutters resemble a K shape and are the most popular option for US homes. They usually measure 5 to 6 inches. A K-style or rectangular downspout sized 2×3, 3×4, or 4×5 inches is suitable.
- Half-round gutters: These gutters are aesthetically pleasing but less effective at draining water than alternatives. They usually measure between 5 and 6 inches, but neither a 5- or 6-inch half-round gutter will hold as much water as its K-style counterpart. Nevertheless, a round downspout that’s 3, 4, or 5 inches in diameter should suit these gutters.
How to Choose a Gutter and Downspout Size
Your gutter size will determine the size of your downspouts. Undersized gutters may overflow and clog. But how do you choose the right gutter size? Generally speaking, 6-inch K-style gutters hold the most water and work the best.
There are a number of factors that will determine whether 6-inch gutters are necessary for you. For instance, homes with steep roofs and homes in areas with heavy rainfall are more likely to need them.
When to choose a half-round or a 5-inch K-style gutter:
- If your roof has a low roof pitch. Water won’t run down your roof too quickly, so you won’t need a jumbo gutter.
- If your roof’s total square footage is on the smaller side. It won’t collect too much water.
- If there isn’t much rainfall in your area.
- If there aren’t trees surrounding your house.
When to choose a 6-inch K-style gutter:
- Your roof has a high roof pitch.
- Your roof has multiple slopes.
- You have a large roof.
- Your area experiences a lot of rainfall.
- There are trees around your house that drop leaves and debris in the gutters.
Not sure which gutter size is right for you? Larger gutters are always the safer option, so if you’re unsure, 6-inch K-style gutters are probably the better choice. However, it won’t hurt to contact a local pro to make sure you pick the best size for your gutters.
FAQ
6-inch downspouts handle 40% more water than 5-inch downspouts. However, they’re also a bit more costly. The choice comes down to each home’s design. It’s important to consider the amount of water your system will have to handle.
Generally, it’s advisable to install one downspout per 20 to 36 feet of guttering. However, you may need more downspouts if your system handles a lot of water. Take note that there shouldn’t be more than 40 feet of space between your downspouts to ensure proper water drainage.
No, you can’t have too many downspouts. And having the right number of downspouts helps water drain efficiently.
DIY or Hire a Pro
Once you pick your downspout size, you can install them as a DIY project if you feel up to it. Learn how to install downspouts in our guide (but be sure that you know how to work safely on a ladder first).
Picking the right downspout size isn’t rocket science. However, when homeowners do pick the wrong size, it can have detrimental effects on their homes. If you’re not sure how to decide, you can get help with your downspout and gutter installation, repairs, and cleaning. Contact a gutter pro in your area that will help you install an effective water drainage system.
Main Photo Credit: Istvan Balogh / Canva Pro / License
13 comments
Comments are closed.