What Size of Rain Gutters do I Need?

October 19, 2020

A durable rain guttering system is vital to upkeep the integrity of your home, and many people take the installation process for granted until it's actually time to choose the most fitting option among all the designs and styles available. You can't jump straight into rain gutter installation without discussing a series of variables with the company of your choice. Some people's favorite design isn't really appropriate for the water density in their area. For others, the most affordable choice can't be properly adapted to the structure of their home. The size of a rain guttering system, for instance, is inevitably tied to the size and layout of your house, and previous evaluation of your property is imperative to reach the best choice.

It's a known fact that all types of gutters are available in different sizes and the shape of a gutter will determine the final size, with standard k-style gutters carrying as much water as larger half-round gutters. Each gutter style can be of 4, 5, or 6 inches, with 7 and 8 inches gutters usually reserved for custom-made works. 5 inches gutters are suitable to most homes, but the frequency and intensity of rainfalls on the area might call for 6 inches gutters, since they can carry more water. Meanwhile, downspouts sizes are available in 2 x 3 inches and 3 x 4 inches.

Choosing a size involves a close look into styles and materials, as well as a healthy amount of basic math. Some parts of the process might be tedious but they will give you a clearer picture of what to look for when discussing sizes and styles with your rain gutter installer.

Roof Calculations

The structure of your roof is an important factor and the first step you need to take before choosing a rain gutter size. Larger roofs not only accumulate more water, they also collect more dirt and leafs from the surrounding area. Meanwhile, a steeper roof will make the water run off much faster. While it's safe to say that both scenarios would benefit from oversized gutters, you still need to calculate the exact area and pitch of your roof to know which size will result in a functional water channeling system.

• Roof drainage area: You have to multiply the length and width of all the parts on one side of your roof and add them together to get the surface area of your roof. Gable-end roofs are the easiest to gauge, with a simple roofline and no more than two slopes to cover in your measurements. If you happen to have a unique roofline with multiple valleys, this calculation also includes the measurement of each surface dividing your roof in.


• Roof pitch: Hold a 2-foot level against your roof and use a tape measure to determine the distance from the center point of the level, down to the roof below. Calculate the resulting number against an angle of 12 inches corresponding to the distance between the roof and the center point of the level. After that, you just have to guide yourself with the figures below to determine the resulting roof pitch factor:



For example, if your measurements from the middle of the level to the roofline are of 4 inches, you have to multiply your drainage area by 1.05, and so on according to the numbers of the chart.

What Goes into Choosing your Rain Gutter Size

After contacting a rain gutter professional, you can look into the installation options (whether you want a sectional or seamless guttering system), the available colors to improve appearance, and the fastening method that will keep your downspouts fixed. The rain gutter installer will also help you choose the best materials depending on the size your prospective gutter is meant to have. The thickness of the gutters is determined by the chosen material, with the overall costs increasing for thicker gutters made out of copper and other sturdier materials.

While the calculations above will give you a clear estimate, both the material and the style of the gutter will play a role in defining the final size of your rain guttering system. Most residential properties solve their water-leaking problems with either a set of 5 inches k-style gutters or a 6 inches half-round gutter, but if you have a unique roofline and/or your area suffers from intense rainfalls, you might need an oversized gutter.

If you're not confident in your calculations when you compare them to the volume of the rainwater and the intensity of the runoff on your roofline, you can benefit from the assistance of a rain gutter installer that has experience working in your city. Being familiar both with rain gutter dimensions and the climate in your area, rain gutter professionals will evaluate your home after scheduling an appointment, helping you interpret the figures to see how much a particular gutter can carry from the drainage area.

Choosing the Downspouts for your Rain Guttering System

Choosing the right rain gutter size also might also entail looking into downspouts size if your drainage area is particularly big. Installed at every 20 feet of a rain guttering system, downspouts are a useful asset to carry rainwater when the building is particularly big and the roofs are too steep.

The right downspout size is also affected by the volume of water and roof's area. The right roof pitch will ensure that all the water flows to the gutter downspouts and away from the foundations. Among the two main options, oversized 3 x 4 downspouts are gaining more traction among homeowners because of their enhanced water-channeling capacity.

If you need assistance to choose the best size and style to make the best of your rain guttering system, the specialists at Rain Gutters Solution are ready to provide clear recommendations and conduct a seamless installation process for you. Get all the information you need for your renovation process calling (305) 270-7779 or filling out the contact form on this website to schedule an appointment. We will satisfy all your needs and ensure the most sophisticated rain gutters for your property.

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