While vital for keeping water away from your foundation, gutters occasionally require special care and attention to keep them clean and functioning. If not properly maintained, gutters can become filled with debris, begin to clog, and even eventually start growing mold. This mold will grow along the undersides of your gutters, coating them with grime. If left unattended, you can wind up with mold-damaged eaves, weakened shingles, and mildew stains.

This article goes over how gutters get mildew and everything you need to know to eliminate it.

Gutter Cleaning Service
The national average price of gutter cleaning is $160, assuming you have about 200 feet of gutters.
Gutter Guard Installation
In general, the national average cost of gutter guards ranges from $650 to $2,000.
Gutters Installation
In general, it costs somewhere between $1,000 to $7,000 to get a full set of gutters installed on your home.
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    Why Do Gutters Mold?

    There are two major reasons why your gutters are molding, one, the gutters have not been properly maintained, and two, your gutters are older or installed incorrectly. If your gutters are not consistently cleaned, unclogged, and maintained, they’ll build up large amounts of plant and animal waste over time. While cleaning out your gutters can be an unpleasant chore, as a homeowner, you’ll want to take care of them to ensure they’re in tip-top shape.

    Plants growing out of gutters filled with dirt and debris
    Image Source: Canva

    For older gutters, mold can be a warning sign of structural damage or the need for repairs. As gutters age, the connections between gutter pieces will loosen and produce small gaps. These gaps will eventually collect plant matter and moisture, which will cause mold growth. Furthermore, the weight of older gutters will cause the screws or spikes attaching the hangers to the fascia to sag. This lilting will expose these holes and the wood behind the gutters to the elements. Now exposed and unprotected, this wood will begin to develop mold around the spike holes.

    When Is the Best Time To Clean Mold off of Gutters?

    You should immediately remove mold from your gutters after thoroughly cleaning and de-clogging the rest of the gutter system. We recommend cleaning your gutters twice per year, once at the end of fall and again at the end of spring.

    Read about how much it costs to have your gutters clean.

    Cleaning your gutter system and removing mold at these times has several benefits:

    • Spring and autumn cleaning removes the maximum amount of debris: Spring and fall produce the most plant debris of any season. Spring flowers, pollen blooms, and seed pods will fill your gutters throughout the season. As for fall, the constant leaf drops, dead tree limbs, and acorns will fill your gutters up to the beginning of winter. If you clean your gutters in the middle or at the beginning of these seasons, your gutters will immediately fill back up, so cleaning at the end is the most optimal.
    • You’ll get the most mold during spring and fall: Moisture in the air is needed to make mold. Since spring and fall are the wettest seasons, they’ll experience more mold growth than any other. You’ll have clean, mold-free gutters for the rest of the year by cleaning and removing mold from your gutters at the end of these seasons.
    • Mild weather and increased safety: There are plenty of safety concerns when cleaning gutters. Of these, extreme temperatures and the weather are two of the most significant. The blistering temperatures of the summer can lead to heatstroke while making roof and gutter materials hot and difficult to handle. The slick ice, high winds, and frigid cold of winter create an increased risk of falling, slipping, and other hazards. Thankfully, the mild spring and fall temperatures possess no such problem.

    What Tools Do You Need To Remove Mold From Gutters?

    Person using a scooper to clean dirt out of gutters
    Image Source: Canva

    Gutter cleaning and DIY mold removal require the right tools. We’ll separate the tools into two groups, one for general gutter cleaning and the other for specifically removing mold.

    To clean your gutters, you’ll, at minimum, need:

    • A ladder
    • Sturdy, waterproof gloves
    • Eye protection
    • Long-sleeved shirt
    • A gutter scoop
    • A garden hose
    • Reliable gutter guards or gutter covers (optional)
    • Ladder stabilizer (optional but recommended)

    To safely remove mold from your gutters, you’ll need:

    • A ladder
    • Waterproof gloves
    • Eye protection
    • A scrub brush
    • Bleach
    • A sprayer
    • A garden hose
    • Ladder stabilizer (optional but recommended)
    • An extendable sprayer wand (optional)

    One final note on using the proper tools: some home improvement sites recommend using a pressure washer (or power washer) for gutter cleaning and mold removal. We don’t, as pressure washing or soft washing gutters can lead to damage, like weakened connectors. Using bleach, warm water, a scrub brush, and a sprayer is enough to get mildew off.

    Read about highly rated gutter cleaning companies and hire a professional to maintain your gutters without the stress.

    How To Clean Mold off of Gutters

    The first step in removing the mold from your gutters is ensuring the rest of your gutter system is free and clear of debris. Removing mold from all the nooks and crannies it can hide in will be impossible if your gutters are clogged with plant matter. If your gutters are already clean, feel free to skip ahead to the instructions.

    Person climbing a ladder to clean out their gutters
    Image Source: Canva

    To clean out your gutters, you’ll need to:

    1. Find a stable place to put your ladder: Firm, solid, flat ground works best. When setting up your ladder, ensure it connects solidly to the wall and does not shift or move. If your ladder wobbles, is not fully secure, or if you are working over a window, always use a ladder stabilizer.
    2. Wear protective clothing: Ladders can be filled with unpleasant materials, like plant matter, animal waste, and roofing materials. You may also encounter live pests that have taken up residence, so you’ll want to ensure you’re fully protected.
    3. Ascend and begin cleaning: Climb your ladder and shovel the debris with your gutter scoop. We recommend working from the corners to the center of each gutter section. If you work from corner to corner, you risk creating clogs in the downspout when you push the materials from one end to the other. Instead, work from one corner to the middle, stop, move to the opposite corner and work toward the middle again. Repeat until all gutter sections have been cleaned.
    4. Thoroughly rinse: Once most of the debris has been removed, now is the time to give your gutters a good rinse. Take your hose and fill the gutters with water. While the water flows toward the downspouts, keep an eye on its speed and flow. If you spot any leaks or downspout clogs (evident from water slowing down before exiting the downspout), you’ll want to repair those.

    Now let’s look into how to clean mildew from your gutters.

    1. Mix a bleach spray, then add to the sprayer: You’ll want one part bleach to three parts water. Mix this cleaning solution and add it to your sprayer. If you have an extendable telescope arm for the sprayer, we recommend attaching it now.
      1. This solution can also remove mold, grime, and oxidation from vinyl siding.
    2. Place ladder: If you have not done so already, find a stable, flat surface for your ladder. You should rest it on the wall below where you’re cleaning and never on the gutters themselves – doing so can lead to damage and is not secure. If your ladder moves, wobbles, or is over a window, we recommend using a stabilizer.
    3. Wear protective clothing: Now is the time to put on your gloves, mask, and eye protection. Remember, bleach will stain clothing, so wear something you don’t mind losing.
      1. Before spraying, remove all potted plants from under your gutters, and cover permanent plants with a drop cloth. Bleach will kill plants and damage soil, so you want to cover the areas beneath your gutters.
    4. First spraying: Use the extendable sprayer to douse mildew-ridden areas of your gutters. This initial spraying won’t remove any mildew but will kill and weaken the mold.
    5. Allow your gutters to sit: Let the bleach mixture sit for 10 to 15 minutes.
    6. Scrub: Douse your scrub brush in the bleach solution and ascend the ladder. Thoroughly scrub the problem areas until they’re free of mold. When scrubbing, do so briskly, but don’t apply too much pressure, as this can warp, break, or loosen gutter connections.
    7. Second rinse: Using the bleach solution, lightly rinse the problem areas again after most of the mold has been removed. This rinse will help kill the remaining mold within the small nooks and crannies that the initial spray and scrubbing might have missed.
    8. Allow gutters to sit again: Let your gutters soak for another 15 to 20 minutes.
    9. Final rinse: Once the bleach has killed the remaining mold particles, all that is left is to rinse with the hose.
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    Final Thoughts

    Moldy gutters are not only unsightly, but they also pose a risk of structural problems. As the mold grows and festers, it will weaken the surrounding wood structures, leading to sagging, moisture damage, and even collapse. If you have gutter mold, we recommend thoroughly inspecting your gutter system after it’s cleaned. Look for unsecured connections, sagging gutter sections, and loose hangers. If you experience constant gutter mold problems, it might be a sign of more serious structural failings, and you should hire a professional to inspect your gutter and roof systems.

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    Sam Wasson

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    Sam Wasson graduated from the University of Utah with a degree in Film and Media Arts with an Emphasis in Entertainment Arts and Engineering. Sam brings over four years of content writing and media production experience to the Today’s Homeowner content team. He specializes in the pest control, landscaping, and moving categories. Sam aims to answer homeowners’ difficult questions by providing well-researched, accurate, transparent, and entertaining content to Today’s Homeowner readers.

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    Lora Novak

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    Lora Novak meticulously proofreads and edits all commercial content for Today’s Homeowner to guarantee that it contains the most up-to-date information. Lora brings over 12 years of writing, editing, and digital marketing expertise. She’s worked on thousands of articles related to heating, air conditioning, ventilation, roofing, plumbing, lawn/garden, pest control, insurance, and other general homeownership topics.

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