The importance of proper rain gutter slope is often understated. The slope of gutters on your home must not drain too quickly or too slowly. Otherwise, it can spell trouble. Your gutters can look like they’re in good condition, free of cracks and leaks, but their slope might be all wrong.
The proper slope, or pitch, of rain gutters is critical to their function. Rain gutters rely on gravity to move water. As such, gutters must have a controlled slope towards a central drain or a downspout.
A downspout is connected vertically to the lowest end of the gutter, transferring the water to the ground without incurring damage.
Incorrect sloping is usually a result of poor installation, but under-supported gutters can also sag, changing the slope. When the gutter doesn’t drain because of poor sloping, the water will back up to the next lowest point and overflow.
The resulting erosion from the uncontrolled runoff can be an expensive problem to correct. Maintaining and evaluating the slope on your gutters and adjusting them as needed can prevent water runoff and damage.
Let’s take a closer look at why the pitch for gutters is essential for proper drainage and functionality.
What Is the Slope, or Pitch, of Gutters?
The slope is the angle at which your gutters should gently descend towards the downspout. It is often so slight that most people don’t even notice it.
The recommended slope ratio for most gutter types is about a quarter-inch to three-eighths of an inch gutter drop for every 10 feet.
The slope will usually start on one end of the gutter, but if the section is very long, the gutter can be installed slighter higher in the center and slope to both ends.
Sloping gutters should be consistent in pitch along the entire length of the gutter until it reaches the downspout.
Depending on your home’s roof type, your gutters may interconnect at each corner and go around the house completely.
Hip roofs are an example of a roof type with gutters all the way around, while gabled roof houses only have gutters on the two long sides.
The actual angle your gutters follow varies, depending on the gutter type, size, and length of gutter section. For example, a 6” gutter can hold more water volume than a 5” gutter.
Because the 6” gutter has more volume, less gravitational force is needed to move the water toward the downspout. The additional water weight increases the force of gravity, so the gutter doesn’t need as much help from the slope.
Conversely, a 5” wide rain gutter holds about 30% less water volume than a 6” wide version. A 5” gutter installed at a shallower angle will drain too slowly. Gutters that can’t empty before refilling again will often overflow, even during a light rain.
Why Is the Slope or Pitch of Gutters Important?
With a correct slope, your gutters will work as designed, helping prevent pooling, overflows, and leaks. If unaddressed, these issues will often damage the roof, siding, foundation, and landscaping.
The following are clues your gutter slopes might need attention.
Pooling can occur both inside the gutter and on the ground. A gutter that sags due to support problems will hold water.
Gutters are not designed to stay full all the time, so the weight of the pooling water puts additional strain on the fasteners as well.
By keeping the correct slope on your gutters, water will enter and exit at a similar flow rate, preventing pools from forming. Too much slope and the gutters won’t hold much water before they empty. Too little slope and the gutters will have too much water and overflow or leak.
Overflows occur when the gutter can’t empty as fast as it refills. This causes a backflow, which spills over from the gutter before it reaches the downspout.
Overflows are among the worst consequences of incorrect rain gutter slopes. Water weighs about 8 pounds per gallon, so the impact can be significant when it falls from the height of a roof.
This is where erosion issues usually begin. If near the foundation, the uncontrolled runoff can erode the side support provided by the ground to the footings, causing a crack.
Ceiling stains along an exterior wall are another manifestation of overflows. If you see this, it’s an indicator your gutters need attention.
The correct rain gutter slope (and gutter size) will allow runoff to flow constantly, helping avoid overflows and pooling.
Leaks are usually easier to fix than overflows but cause similar damage. Leaks are often found at joints and seams but can also appear at fittings, like an outside or inside corner.
The correct slope allows the runoff to flow efficiently, reducing the pressure on the joints and seams. This also keeps the average water weight inside the gutter relatively low, reducing the strain on the fasteners holding the gutter to the fascia.
Applying a high-quality sealant is often all you need to repair a leak, but some leaks are worse than others. Keeping your gutters sealed and clean goes a long way toward preventing leaks and the resulting damage they can cause.
Benefits of Proper Gutter Sloping
When a gutter slope is positioned correctly, it prevents the problems discussed in the previous section. It also provides many advantages, including the following:
- Roof Protection: The correct slope on your rain gutters will help prevent the common causes of roof sheathing damage. Overflowing, leaking, and pooling can allow water under the shingles, leading to wood rot.
- Reduction of Clogs, Corrosion, Pests, and Ice Dams In Your Gutters: Keeping your gutters clean and at the correct slope will keep the water moving and reduce clogs. Proper sloping prevents pooling, significantly reducing the chances of corrosion. Pest problems are less likely because they are not attracted to a dry gutter.
A proper gutter slope in winter can also help prevent ice dams by keeping the runoff moving. Re-frozen runoff causes ice dams, so an adequate gutter slope keeps the runoff moving, helping prevent it from freezing.
- Water Harvesting: The right gutter slope also ensures that all of the water in the gutter makes it to the downspout, where it can be harvested in a rain barrel and used rather than wasted.
- Siding Protection: Because the siding is under the gutters, leaks or overflows caused by an improper gutter slope will land on the siding. Often, this leads to premature wearing of the siding, which appears as discolored streaks.
- Landscape Protection: Protecting an expensive landscape is among the best reasons to keep your home’s rain gutters on the proper slope. A single overflow or perpetual leak can cause soil erosion under thick mulching.
How to Determine and Adjust the Slope or Pitch For Gutters
Calculating the slope of gutters isn’t rocket science, but a little math is involved. You’ll need to access your gutter, so you’ll need a ladder. You’ll also need a 48” level and a measuring tape. Be sure and use your tools safely and wear personal protective equipment.
Generally, the slope will be based on the roof area served by the gutter, the amount of rainfall, and the gutter system design. The gutters will have been originally designed and sized for the average expected rainfall in your area and the size of your roof.
Measuring and adjusting gutters is often more than homeowners want to take on. Hiring a gutter professional is often the best option, as they have the tools and training to do the job quickly and efficiently. But if you want to try it, we have a few tips.
You’ll be measuring a ratio, not an angle, so you only need two numbers. Place the 48” level on either end of the gutter along the underside. Now raise or lower the level (depending on which side you’re on) until the bubble in the level is between the two marks.
Measure the gap between the top of the level and the underside of the gutter. The slope angle is within range if the measurement is between ¼” and ⅜”. If the gap is more than ⅜”, the gutter slope is too steep. If the gap is less than ¼”, the slope angle is not steep enough.
Most gutter systems installed today are seamless guttering made from aluminum and formed on-site.
Seamless gutters are installed using a hidden hanger. The hidden hanger spans the top of the gutter’s opening from front to back and terminates into a lag screw. This lag screw can be loosened, allowing an adjustment of the hanger’s location on the fascia board.
You can move the hidden hanger anywhere along the length to correct a problem. Just relocate the hanger to where the gutter sags to correct the slope and re-install the lag screw.
If you have old, sectional gutters, they will probably use straps, gutter spikes, or gutter screws. These can also be removed and relocated to straighten a joint or re-support a sagging section.
Understandably, you may feel more at ease asking a gutter professional to adjust the gutter slope.
Contact Our Gutter Experts to Ensure a Proper Rain Gutter Slope For Your Home
Gutters protect your home’s foundations, siding, roof, and landscaping from water damage. However, gutters only work their best when installed at the correct slope.
We have a local team of gutter specialists servicing homes across the U.S. We specialize in installing quality seamless gutter systems and the correct slope of gutters to ensure maximum efficiency.