Why Gutters Overflow and How to Fix Them

Causes of overflowing gutters and what you can do to prevent this damage-causing gutter problem.

Water spilling over front of gutter

Overflowing gutters cause water damage to foundations, basements and crawl spaces, concrete walkways and patios, fascia boards, siding, and landscaping.

Rain gutters run along the base of the roof and channel water away from your home. This protects your home and landscaping from water damage. But when gutters overflow during a heavy rainstorm, this can cause water damage, including foundation cracks, flooded basements, cracked concrete, rotted fascia boards, discolored siding, and damaged landscaping.

Top 6 Causes of Overflowing Gutters

Although gutters are simple by design, they are prone to malfunction, especially with age. They need periodic cleaning and when that doesn’t happen, the gutter clogs. To make matters worse, many types and brands of gutters on the market are poorly designed and cheaply built. Finally, improper installation can cause gutters to clog and overflow or function ineffectively.

These are the six most common causes of overflowing gutters.

  1. Clogged Gutters

    Gutter filled with leaves and twigs

    Leaves, twigs, and debris block the flow of water through the gutter.

    If your gutters aren’t covered, they will get dirty and clogged over time. Failing to clean the gutters regularly leads to clogs that either slow or prevent the flow of water entirely. When this happens, water spills over the gutter onto the ground below, putting your siding, foundation, and landscaping at risk of damage.

    Gutters clog in a number of ways:

    • Trees close to your home shed leave that either fall or blow onto the roof and into your gutters and downspouts.
    • Poorly designed or improperly installed downspouts trap debris - typically at the entry and exit points - and block the natural flow of water.
    • In regions where there’s snow and ice, thawing snow slides onto cold gutters, and some of the melting snow refreezes, causing an ice dam to form, which clogs the gutter.

    How to Fix: Clean your gutters at least twice a year - more often, depending on how wet your climate is and how many trees you have in your yard. When it’s time to upgrade your gutter system, choose one that requires less maintenance. Covered seamless gutters are less prone to leaking and protect against clog-causing debris. This describes the Gutter Shutter system, which is backed by a lifetime no-clog warranty.

  2. Improperly-Pitched Gutters

    For gutters to drain properly, they should slope ¼ inches for every 10 feet toward the downspout. If this isn’t the case when water flows through the gutter, some leaves, twigs, pine needles, and other debris can remain behind. When clogs form, water backs up behind the clog and spills over the side of the gutter. Too much slope causes water to spill over the gutter, especially during heavy rain.

    How to Fix: You can check the slope of the gutter and try to realign it. If you have a metal gutter that’s sagging or bent, upgrade your gutter system.

  3. Small Gutters

    Gutter filled with water

    A high volume of water can fill a gutter and cause overflowing.

    Sometimes a standard 5" gutter isn’t enough to handle a heavy downpour. The gutter might not be big enough or effective enough to handle the volume of water running off the roof, especially during heavy rains and if you have a large or steep roof. When it comes to properly draining water away from your home, the quality of your gutters matters, too: a cheap, DIY system is more likely to clog, sag, or pull away from the home or fail to keep up when it matters most.

    How to Fix: If your gutter is clear, but still overflows during heavy rain, upgrade your gutter system. In some cases, you might need additional downspouts installed. Gutter Shutter is a high-capacity system designed to carry 20% more water than 5” gutters.

  4. Clogged Downspouts or Underground Drains

    Short downspout with tall plants growing underneath

    Downspouts that are too short or clogged can lead to serious water damage.

    If water is flowing over your gutter and not through your downspouts, your downspout or underground drain could be either partially or completely clogged. This causes water to leak or overflow in different sections along the gutter system and damages your siding and foundation over time.

    Check for these signs of a clogged downspout or underground drain:

    • Water is spilling out of the drainage pipe or pooling around the bottom of the downspout during rain.
    • Pavement, concrete, or decking is stained near the drainpipe.
    • The ground near the drainpipe is soggy or oversaturated.
    • Water is leaking out of the downspout seams or elbows.
    • Water is leaking from gutter seams or spilling over the sides of the gutter.

    How to Fix: Have your gutter system inspected to see if it’s time for repair or replacement. Make sure your new gutter system has wide-mouth outlets and protection against clog-causing debris. Our 3x4" downspouts have twice the capacity of standard 2x3" downspouts. Gutter Shutter offers RainChute downspout extensions, installed at the end of the downspouts to effectively channel water further away from the foundation. For below-ground drainage, we recommend the LawnScape Outlet keep out debris, mice, and other small critters from getting in and clogging the system.

  5. Too Much Water Flow at Roof Valleys

    Leaves collecting in roof valley

    Water can overshoot the gutter where two sections of the roof meet.

    Water flows faster down roof valleys than other parts of the roof. If you have a roof with valleys, you might notice water overshooting the gutter at sections where two roof surfaces meet, especially during heavy rain.

    How to Fix: Splash guards are designed to divert water to keep it from overshooting the gutter, but most splash guards are made with cheap materials that fail to withstand heavy water flow. A large, steep roof with long valleys requires high-performance gutters big enough to handle the volume of water. Have your gutter system looked at by a professional who can advise you on whether installing larger gutters will stop the overflow.

  6. Loose Gutters

    Gutter with a loose spike

    Loose hangers or spikes can cause gutters to tilt away from the house, allowing water to spill over.

    Gutters that are sagging or loose and pulling away from the fascia are usually a sign that the hangers or fasteners are loose, deteriorated, or spaced too far apart to support the weight of the gutters, especially if they become clogged with wet leaves, twigs, and other debris. When the gutter sags, water spills over the sides, similar to tipping a glass of water.

    How to Fix: When gutters are either loose or completely fall off, this exposes the fascia to wet weather and increases the risk of mold or rot. Have your loose or sagging gutters checked by a professional before bad weather strikes. The Gutter Shutter system has a high back that protects the fascia board and extra-strong brackets that support the front and back of the gutter to protect your foundation from potential water intrusion and structural damage.

If your gutters are overflowing or clogged, check out the Benefits of Our System or contact us to schedule a free gutter evaluation and estimate with your local Gutter Shutter contractor.