How to Easily Calculate Gutter Slope

Are your gutters not draining right? Or are you looking to install new gutters?

In this guide, we’ll talk about how to easily calculate gutter slope. We will also go over some tips for setting the right gutter slope super easy with minimal tools.

We want the rainfall that comes off of your roof to flow through your downspout and away from your home. Easy peasy.

sloped gutters

What Should the Slope of Gutters Be?

The ideal gutter slope is 1/8 – 1/4 inch for every 10 feet of gutter.

When setting the slope of your gutters, its important not to under slope the gutters, or they may have trouble draining when it rains, leading to issues like gutters overflowing. The gutters may also hold water for several days at a time, which can put extra weight on your gutters and can weigh them down, leading to your gutters sagging.

With standing water in your gutters, you may also run into issues like mosquitoes living near your home and even mud buildup which leads to clogging.

On the other hand, over sloping your gutters has it’s own host of issues too.

With gutters that are too aggressively angled, it can limit the amount of water your gutters can handle making them less effective overall. Not to mention, the water may overshoot your gutters damaging the landscaping surrounding your home.

If your gutters are too sloped, they may look misaligned and strange, ruining your homes curb appeal. They will look crooked and out of place.

So naturally, we need to find the middle ground.

A gutter slope is 1/8 – 1/4 inch for every 10 feet of gutter will ensure proper water flow to your downspouts without looking out of place and causing any issues.

How to Calculate Gutter Slope

Gutter DistanceTotal Slope
10 feet1/8 – 1/4 inch
20 feet1/4 – 1/2 inch
30 feet3/8 – 3/4 inch
40 feet1/2 – 1 inch

To calculate how much drop your gutters have, first measure the total distance your stretch of gutters have. Then add up 1/8 -1/4 inch for every 10 feet of gutter you have.

For example, if the side of your house has 40 feet of gutter, you would need 1/2 inch – 1 inch slope for your 40 feet of gutter

If you don’t want to measure the drop with a measuring tape, here is another way to do it. A 1/8 inch drop over a 10 foot section of gutter is not something that is easily measured with measuring tape.

Instead you can use a level.

With the level you want to hold up to the gutters and see how aggressively they are sloped. If you notice the bubble in the level is heavily tilted either direction, it’s a sign they may need to realigned.

Ideally, the gutters should be barely sloped and the level should just show the air bubble slightly off-center. If the bubble in the level is slightly offset, but still in-between the lines, you have found the right slope for your gutters.

I’ve included a video above showing the method for getting the perfect gutter slope.

Is Gutter Slope Important?

Gutter slope is extremely important to ensure the proper water flow in your gutter system. Properly sloped gutters will make sure water enters your downspouts and is directed away from your home.

The gutters are important for protecting your siding, foundation, landscaping, and interior of your home from water damage. Issues like soil erosion and foundation repairs can be costly and time-consuming to deal.

So it’s best to make sure your gutters are properly working and maintained.

What Problems Can Arise From Incorrect Gutter Slope?

If you gutters are not sloped correctly, there are 3 main issues you will run into.

Not Enough Slope

If your gutters are installed dead flat, you will notice that water does not drain from them fast enough.

During heavy rainfall, water will fill up in your gutters and overflow before it has a chance to drain out through the downspouts.

The overflowing water can damage your home and lead to costly siding repairs, interior ceiling water damages, and foundation erosion.

Add a little bit of slope can ensure that your gutters work properly, even during heavy rainstorms.

Sloping Gutters Away From Downspouts

If your gutters slope away from your downspouts, the water will pool up in areas where there is no exit for the water.

This will also lead to overflowing. You will also notice water staying in your gutters for a long period of time after rainstorms, weighing down your gutters. Over a long enough period of time, your gutters will begin to sag and become misaligned.

It’s always wise to slope your gutters towards the downspouts for the ideal water flow.

Too Much Slope

If your gutters are sloped too much, you will notice your home looks crooked. The gutters are often overlooked as a piece of your homes aesthetic, and in this case, they will detract from the curb appeal.

The overly sloped gutters can cause real damage to your home in addition to hurting the curb appeal. The gutters will not be able to carry as much water when it rains and you may run into problems where the rain overshoots the gutters.

When it comes to gutter sloping, you really want to be in the goldilocks zone of 1/4″-1/8″ of slope.

Not too much slope, not too little slope. Just the right amount of slope.

Do You Need to Add a Downspout?

If you notice your gutters are overflowing, it may not be because your gutters are improperly sloped. In fact, it could be due to a lack of downspouts.

The ideal number of downspouts is one every 25-35 feet. So if you notice your downspouts are spaced too far apart, that could be the root cause of your issue.

Another common problem is that the downspouts may be too small as well. You always want to have properly sized gutters and downspouts for your home.

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