Your gutter and drainage systems are essential for keeping water away from your foundation and making sure that your lawn doesn’t flood. However, if you don’t take the time to properly maintain your gutters, they 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. As a worst-case scenario, this mold and mildew could also become a bigger structural problem and a health habit.

The team at Today’s Homeowner knows that you want to take the best care of your exterior of your home. That’s why I’ve compiled a guide for you about how mildew and mold can form in your gutters, as well as a step-by-step guide for how to clean your drainage system effectively.

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. The first is that the gutters have not been properly maintained. The other reason could be that 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 make sure that they’re in tip-top shape.

Plants growing out of gutters filled with dirt and debris
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You should especially pay attention if you find mold in your gutters. This is because mold can be a warning sign of structural damage or a need for repair. But how does mold develop in your gutters in the first place?

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 tilting 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. This can cause damage both to the interior and the exterior of your home.

Can Moldy Gutters Harm My Health?

While mildew and mold are generally not harmful in small amounts, mold can have serious impacts on your health if it is left unchecked. This can range from mild allergies to serious long-term complications that can result from toxic mold exposure. If you don’t clean your gutters for a long time, mold and mildew can affect not only the side of your house but the interior of your home as well, making the problem all the worse.

For this reason, I always recommend taking the time to clean and inspect your gutters so you can stop mold problems before they start. So let’s get into how you can take the steps to clean your gutters, starting with what time of year is best to do so.

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

I recommend cleaning your gutters twice per year, once at the beginning of fall and again at the end of the spring. You will need to immediately remove the mold from your gutters after fully cleaning and de-clogging the rest of the drainage system.

While this is a process that you can do yourself, you can also research how much it costs to have your gutters cleaned.

Cleaning your gutter system and removing mold at the times that I recommend 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 do not cause this problem.

Now that you know what time of year is best to clean your gutters, let’s look at what you’ll need to remove mold from your drainage system.

What Tools Do You Need To Remove Mold From Gutters?

Person using a scooper to clean dirt out of gutters
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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 the following materials in addition to the above tools:

  • A scrub brush;
  • Bleach;
  • A sprayer;
  • A garden hose;
  • 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. As a member of Today’s Homeowner’s expert team, I don’t recommend using this tool, 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 and mold off.

Keep in mind that if you don’t have the above tools or are concerned about cleaning gutters yourself, I recommend reading about our highly rated gutter cleaning companies so you can 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 making sure 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, make sure 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: Gutters 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 make sure you’re fully protected.
  3. Ascend and begin cleaning: Climb your ladder and shovel the debris with your gutter scoop. I 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, which will be evident from water slowing down before exiting the downspout, you’ll want to repair those.

Now let’s look into how to clean mildew or mold 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, it is best to attach it now.
  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, it is best to use 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. This is why I recommend moving all potted plants from underneath your gutters and covering permanent plants with a drop cloth before spraying. This is because bleach kills plants and damages 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.

    Keep in mind that while you can do the above process yourself, you may want to invest in a professional gutter cleaning service if the mold and mildew on your gutters is extensive.
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Final Thoughts

Moldy gutters or ones that are filled with mildew are not only unsightly, but they can also pose a risk of structural and health problems. As the mold grows and festers, it weakens the surrounding wood structures on the exterior of your home. This leads to sagging, moisture damage, and even collapse.

If you have gutter mold, I recommend that you thoroughly inspect your gutter system after it’s cleaned. You want to 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.

Frequently Asked Questions About Gutter Mold

What causes mold and mildew growth in gutters?

Mold and mildew thrive in damp, shaded areas with organic debris like leaves, twigs, and dirt that accumulate in gutters over time. If you don’t clean your gutters, this mold can affect the structural integrity of your home by damaging the gutter system and siding.

Is gutter mold and mildew harmful?

While typically not toxic in small amounts, mold can cause respiratory issues for some people and lead to staining and structural damage on the house itself if left unchecked. This is why it is always recommended to clean your gutters at least twice a year.

How do I remove mold and mildew from my gutters safely?

As written in the above article, the best way to remove mold and mildew from your gutters yourself is by using a stiff brush and a bleach solution. You can also opt to use a commercial gutter cleaning product.

What can I do to stop future mold growth?

The best ways to stop mold from growing in your gutters is to install gutter guards, regularly clean your gutters at least twice a year. You should also make sure that your gutters are properly aligned so water drains away from your home.

How often should I clean my gutters to prevent mold build-up?

The team at Today’s Homeowner recommends cleaning your gutters twice a year, in spring and fall. This allows you to clean your gutters when the weather is nicest and also avoid having to remove debris later in the season.

Are there any natural mold removers that I can use on gutters?

If you don’t feel comfortable using bleach, using vinegar, baking soda, or hydrogen peroxide in small amounts can work well as eco-friendly gutter cleaners. Be sure to always check to make sure that your cleaning products are safe to use on the type of gutters that you have. I also recommend moving any plants from underneath your gutters if possible to prevent the cleaning solution from draining on them.

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Reviewed for accuracy, cost data, industry best practices, and expert advice by Nikki Stavile
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Sam Wasson

Staff Writer

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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Nikki Stavile

Nikki Stavile is a writer based in Tucson, Arizona. As an avid backpacker and passionate environmentalist, her work often focuses on sustainable movements at the personal and societal level.

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