What Causes Gutter Overflow? 6 Common Causes

What Causes Gutter Overflow?

There are a few different things that could cause gutter overflow or leaks to happen in your gutter system. A gutter overflow could be caused by a number of different things such as clogged gutters or pitch issues.

The best way to determine the cause of exactly what is going on, is to observe the water overflow happening during rain. Let’s go through the 6 most common reasons causing gutter overflow.

1. Clogged Gutter Downspout

The number one cause of all gutter problems, including gutter leaks and gutter overflow, is clogged gutters.

All debris that lands on your roof eventually washes into the gutters. If the debris is small enough and the gutters are configured properly, then the debris will flow right through the gutter and downspout system. As long as there are no obstructions in the downspouts. All it takes is one twig or leaf to get snagged in the pipe where it creates a traffic jam. Soon more and more twigs and leaves get stuck in the same spot until they obstruct the water flow and form a clog or blockage.

 

Once your downspouts become clogged with debris the water is not able to drain properly. What happens next is the gutter will fill up with water until the water starts to pour over the top. Overflowing gutters have many different looks. In the video below you can see how the water gently flows over the gutter face to where it eventually drips down.

To the untrained eye you may think that this gutter is leaking because of all the drips. We get it. The section that is dripping is about 10 feet wide! But make no mistake, the water is actually flowing across the front face of the gutter to where it drops once it reaches the underside of the gutter.

Solution

A thorough gutter cleaning should do the trick. In the case of downspout clogs, we recommend calling a professional as you will likely need additional tools to dislodge the clog.

2. Incorrect Gutter Pitch

Anytime we see water going over the end cap of the gutter we automatically assume the Gutter Pitch is off. All gutters are tilted or “pitched” so the water easily flows towards the downspout. Since water is not able to flow uphill all the gutters must be pitched in accordance with the downspout locations. Sometimes the downspouts are on the sides of the home and the water has to make it around a few corners to get there. As long as everything it pitched correctly the water will flow properly.

Whenever you see water going over the end cap or sometimes even leaking through the end cap the gutter is tilted the wrong way. The water should never not be moving towards the downspout. The solution to this problem is to have the gutter re-pitched to the proper direction. If the gutter was back pitched for a long period of time the end cap seal might have worn off. You’ll see the water seeping through the end cap if this has happened. To fix it you’ll need to re-seal the end cap with a waterproof based sealant. We always suggest scraping the old caulk away before applying a new seal.

CLICK HERE for more information regarding Gutter Pitch.

Solution

To address the issue of gutter overflowing caused by incorrect pitch, it is crucial to ensure proper gutter alignment and angle. This will allow rainwater and debris to flow smoothly and efficiently through the system, preventing any accumulation and potential overflow.

3. Loose Gutters

Gutters that have become loose will leak or overflow in different ways depending on how loose the gutter is. For example a gutter that is slightly loose may only have a little water going behind the gutter that flows down the wall. Where as if the same gutter was about to fall off of the home all of the water would be pouring out of the gutter like a bucket.

 

When gutters become “Very Loose” the water usually forms a spout or a lip on the face of the gutter to escape. In the short video below we show a gutter that is starting to lean slightly and the water has formed a spout to escape, creating the gutter overflow.

If this gutter isn’t re-secured with new hardware soon it could fall of the wall. All it takes is one major storm. If you can see the inside of your gutter from the ground or street level chances are that your gutter is “leaning” or is “tilted.” Once the gutter tilts or leans the water will just fall out, causing overflowing gutters. Sometimes when the gutters are loose the gutter will fill all the way up with water. Then once it gets to a certain point the whole gutter shifts and dumps the water out on it’s own like a troth.

Read also: Loose Gutter Guide: The Stages of Loose Gutters

Read also: Gutter Repairs Guide

Solution

Prompt action is essential to avoid potential damage and improve the overall effectiveness of the gutter system. The first step is to conduct a thorough inspection to identify the cause of the problem, which could range from deteriorating brackets to loosened fasteners.

Once the source is determined, tighten or replace any damaged brackets and fasteners to secure the gutters firmly to the structure.

4. Fascia Board Damage

When the water is going behind the gutter it is sometimes hard to tell the cause from the ground. We suggest a process of elimination to determine the cause.

First check the downspouts during rain to see if water is coming through them. If no water comes out of the downspouts then they are clogged. You can determine if it is a pitch issue by checking if the overflow is happening near a downspout. Loose gutters you can usually see a gap behind the gutter. If you check all 3 of those items off the list then your left with drip edge issues.

 

Water going behind the gutters is a major problem to your home. Gutters are mounted to a trim board called “Fascia Board.” This wood needs to stay solid so it can support the weight from the gutters. However if the wood is in contact with water it will eventually become soft and start to rot.

 

More Info on Fascia Board Damage

More info on Drip Edge

5. Clogged Underground Drain

Whenever water is overflowing your entire gutter system we automatically think Clogged Underground Drains. The signs for clogged underground drains are the same as clogged downspouts, just more extreme. Water that is unable to drain through the downspouts ends up pouring over the gutters, especially near the downspouts. However when the water overflows the entire gutter system then something is very wrong.

If your entire gutter system looks like this and you do not have underground drains then you either have clogged downspouts all around your home, or your entire gutter system is loose and/or pitched incorrectly.

Read also: Clogged Gutter Drains: How to Inspect & What to Do

Solution

Professional plumbers equipped with drain cameras should locate and assess the blockage’s extent.

6. Water Going Over The Gutters

Sometimes water will look like it’s going directly over the gutters. It’s almost like the water doesn’t even go in them at all. There are only a few situations that could cause this so it’s easy to determine the cause. Here are the most common causes of gutter water overflow:

a) Gutter Covers

The main cause of water going over the gutters is gutter covers. Especially in problem areas like under roofing valleys or roofing seams. If your home had problems with water going over the gutters in these high traffic areas before gutter covers. The problem is going to be worse with the covers. Different styles of gutter covers all handle the water in their own way. Some have better water flow than others. The only solution to this is to add splash guards to your problem areas. If that doesn’t work than the only other option is to remove them.

b) Roofing Valleys/Roofing Seams

When two different sections of roof come together they form a valley. The valleys become water channels when it is raining. Water flows down them where it splashes down into the gutter or miter section below. The only option in this situation is to add splash guards below the roofing seams and problem areas. You could always upsize your gutters with a larger size too.

c) Obstructions

Something as simple as a pile of leaves or a pile of pine needles could cause the water to go over the gutter in that spot. Especially under a roofing valley. The water comes flying down that channel and if it hits a pile of leaves it sometimes will bounce right back out of the gutter.

d) Roof Pitch/Shingle Over Hang

When we mention roof pitch we are referring to how steep the roof is. The steeper the roof is the more difficult it is for the gutters to catch the water. Especially with gutter covers. If the roof is too steep you won’t be able to have gutter covers installed to your gutters at all. In some situations you are able to install Gutter Wedges so the gutter sits more level.

Shingle overhang refers to how far the shingles stick out over the roofing edge. If the shingles stick out to far the water will go straight over the gutters. The only solution here (besides removing shingles) are gutter wedges or upsizing your gutter.

Gutter Overflow Solutions

In most cases, a gutter clog is the cause in which case a thorough gutter cleaning should do the trick. If that doesn’t fix the gutter overflow, you might have to look into other reasons why that might be happening.

The best way to go about figuring it out is to observe your gutters during rain. If you can determine where the water is coming from you can usually determine the cause. Or at least you can narrow down the list of possibilities. You might need to: 

• Repitch gutters
• Unclog underground drains
• Repair the gutter fascia board
• Install a gutter overflow diverter