Understanding Gutter Slope and How to Measure It

By Amanda Lutz Updated March 21, 2024

Your home’s gutters are a critical part of keeping the house dry and protected. They guide water down from the edge of your roof before leading it away from the home’s foundation. Gutters and fascia boards must be in good condition to function properly, though, and gutters also need to be the correct slope. Read about gutter slopes in the guide below, including tips on how to correctly measure slope and how to fix problems you may encounter while trying to correct water flow.


Importance of Correct Gutter Slope

Gutters may look like they sit parallel to the roofline around your home, but they actually have a small angular tilt that guides water toward the nearest downspout. This gradual slope can be up to 0.5 inches per 10 linear feet, which allows for a steady flow of water during heavy rain.

If the slope is too shallow, water may move sluggishly or pool, causing the gutters to fill up too quickly and spill over the edges. Spilled water can cause erosion, foundation damage, and rot on the side of your home.

If the slope is too aggressive, the gutters will look crooked and reduce your home’s curb appeal. The gutters might also break or warp under the weight of excess water.


How to Measure the Slope of Gutters

If you believe your gutters aren’t performing correctly or it’s been years since a professional last inspected them, then we recommend measuring the slope of each gutter. The slope can change after years of exposure to the elements or to heavy rain.

Measuring the slope of gutters is simple and requires just a few tools: a tape measure, a pencil or piece of chalk, a level, and a piece of string. Follow the steps below to measure each gutter slope:

  1. Locate the end of the gutter that’s furthest from the downspout. This end should sit at the system’s highest elevation. Mark the point at which the top or bottom edge of the gutter sits flush against the edge of your home, and tie or tape the end of a string at that point.
  2. Measure a distance 10 feet along the gutter and mark the spot on a level line with the other spot. Pull the string until it is taut and use a level to determine whether it’s straight. The edge of the gutter should be between 0.25 and 0.5 inches below the marking.
  3. Repeat the second step every 10 feet along the gutter until you reach the downspout. The ratio of a 0.25-0.5 inch drop per 10 linear feet should be the same across the gutter.
  4. Repeat the entire process for every gutter around your home.

This process will tell you whether your gutters have the slope necessary to function correctly. Follow the tips below for the best results:


Common Problems with Gutter Slope

Just a fraction of an inch can drastically affect the flow of water around your home, especially if you live in an area with lots of rainfall. Consider these common problems of either under- or over-slanted gutters to avoid water damage.

Foundation Damage

Gutters are designed to direct water toward a downspout. Each of your home’s downspouts should have a footer that angles water away from the edges of your foundation and far from the property. Some homes also have French drains or extended downspouts to control the flow of water more precisely.

Below are the risks of improperly slanted gutters and of malfunctioning downspouts:

  1. Water will overflow and hit the ground around your foundation and landscaping in hard sheets. This could chip away at the soil.
  2. Water will sit around the edge of your foundation with nowhere to go. This may overwater the soil, causing clay-based soils to expand and shift. The process will push soil away from the deep edges of your foundation, leading to erosion, sudden cracks, and long-term foundation damage.

Overflow

Gutters that don’t have the correct slope may overflow in three directions: the outer-facing edge, the edge against your attic, and the downspout end cap. If your gutters have no slant or slope in the wrong direction, water can pour over the drip edge.

If the gutter overflows from the long outer edge of the gutter or the short end near the downspout, excess water will fall with particularly strong force. If water pours over the interior long edge, it can seep into the eaves, attic, and insulation along the edge of your roof. This could lead to mildew buildup, rot, pest infestations, and softening eaves and soffits.

Water Pooling

Light rainstorms or slight under-slopes may seem innocuous, but they can still cause damages. In these cases, water can sit stagnant in the gutters because it lacks enough momentum to move through the gutter to the downspout. This can lead to the following problems:


How to Fix Slope Problems

Address gutters that don’t have the proper slope (between 0.25 and 0.5 inches) quickly. You may need to realign poorly sloped lengths or replace gutters entirely.

Realigning Your Gutters

Follow these steps to realign your gutters:

  1. Find the hangers for whichever gutters have the wrong slope. Some hangers screw through the gutter walls while others are separate hooks in which the gutters sit. 
  2. Reposition the hangers. Loosen the hangers, and move them up or down to correct the angle. Then drill a new hole for the fastener or screw it into place.
  3. Continue to change the gutter slope. You may only need to adjust one gutter or may need to change multiple gutter lengths in a sequence. Carefully check each gutter length for the right amount of slope before moving on to the next.
  4. Seal the seams. Gutters are typically collections of several sections that slot into place or fasten together (some homes have custom seamless gutters that are a single solid length, though). Seal the interior seams with a silicone caulk so water can’t drip out.
  5. Check the entire slope again. Make sure the repositioning didn’t cause any sections of gutters to fall outside of their recommended slope range.
  6. Test the gutters by pouring water into them. Watch the flow of water to make sure it moves properly, doesn’t pool, and doesn’t seep through any leaks.
  7. Seal holes along your roofline wherever you repositioned the gutter hangers. Fill the holes with wood putty and paint over them to stop moisture and pests from accessing the wood.

Hire a professional gutter service to realign, repair, and inspect the gutters if you don’t want to complete this project yourself or if you can’t easily access the gutters.

Replacing Your Gutters

Improper gutter slopes can cause serious damages, and simply realigning gutters may not always fix issues. Replace gutters that have bent, warped, or rusted. Consult professional gutter installation contractors to help you decide on the best course of action.


Our Recommendation

Take good care of your gutters to keep them performing well. This includes measuring and realigning the slopes of your gutters to help protect your roofline, eaves, foundation, and the gutters themselves.

If you notice your gutters pooling or developing a tilt, make sure the slope at which they sit is between 0.25 and 0.5 inches. Realign gutters that have shifted too much and replace them if they’re beyond the point of standard gutter repair.Properly installed gutters protect your roof and foundation from water damage.

The sooner you correct slopes with do-it-yourself (DIY) methods or by hiring a gutter company, the less likely water is to damage your home during the next storm.


Gutter Slopes FAQ

What is the minimum slope for gutters?

A general rule of thumb is that gutters should go down by at least 0.25 inches for every 10 linear feet. Some builders install gutters at a 0.125-inch slope because of gutter design and the region’s climate.

What is a common slope for a gutter?

A common slope for a gutter is 0.5 inches over 10 linear feet, which is the maximum ideal slope for gutters. A steeper slope might lead to overflow around the downspout.

What is the best pitch for gutters?

The best gutter pitch is no more than 0.5 inches per 10 feet of length. This slope pushes the water down toward the downspout but isn’t so severe that it causes water to overflow.

How level should gutters be?

Gutters should not be level. All gutter systems should have a slight slope that’s between 0.25 and 0.5 inches per 10 feet to facilitate water flow.