How to Remove Mold and Mildew From House Siding

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During a routine walk around your home, looking for any damage or issues that may need to be fixed, you notice stains on the siding of your house. Mildew, or even worse, mold may be the culprit. Whether it’s lighter white or tan, or darker black spots, you should take immediate action to clean these damaging fungi from your home.
Mold and mildew can stain your siding, cause wood to rot, and impact allergies or make occupants sick. When you remove the mold and mildew from your siding, you protect your home’s market value and your family inside.
Houses today use different siding materials including vinyl, wood, aluminum, brick, and stucco. Each type is susceptible to mold and mildew, but not all siding is created the same and it’s important to keep the materials in mind when removing mold or mildew.
In this four-part article, Part 1 helps you identify the problem (whether mold or mildew), Part 2 discusses steps to remove mold and mildew from your siding, Part 3 goes over when to call a professional, and Part 4 shares tips for preventing the growth of mold and mildew in the first place.

Part 1 of 4: Identify if your house has mold or mildew

The first step in removing mold or mildew from your home’s siding is to identify the problem. Once you see a problem, and before you go about cleaning up an unsightly stain, take the time to determine whether its mold or mildew. Both mold and mildew grow in damp, shaded areas of your home, but have differing needs when it comes to cleaning.
While both types of fungi, mildew is a milder problem caused by excess moisture. Mildew is usually a gray/white or light brown color. It is powdery and resides on the surface of materials. Mildew is easier to clean and notice. Mold, however, can be more difficult to find as typically the first sign is a bad smell. Mold comes in a rainbow of colors and is usually “fuzzier” than mildew appears. In addition, the mold you can see is often not all there is.
Both mold and mildew can cause allergic reactions, but mold can cause allergic reactions, skin irritation, respiratory infections, and even poison occupants. Both can be serious and should be immediately addressed and cleaned.

Part 2 of 4: Remove the mold or mildew from your siding

To keep your home looking beautiful it is important to immediately remove the growth of mold and mildew on your siding. Follow these steps to remove mold or mildew from your home:
Step 1: Cover plants up. Before spraying any cleaning solutions onto your home, be sure to cover up any plants or other items that may be damaged.
Step 2: Test a small spot. Test any cleaning solution and tools on a small, out-of-sight portion of your siding to ensure that the treatment will not cause damage.
Step 3: Choose your cleaning solution. The main types of siding are aluminum, wood, brick, stucco, and the most popular siding, vinyl. While a pressure washer is a fast way to remove dirt, it is not recommended for use on all siding types or for a light cleaning.
Remember, just because it may be okay to use on one brand of vinyl siding does not mean it is recommended for use for another. Before using a pressure washer, check to see if it is recommended by the manufacturer for cleaning use.
Depending on how much mold or mildew is on the siding, the following cleaning options can make quick work of the unwelcome fungi:
Light staining
  • Water
Light to medium staining
Medium to heavy staining
  • Laundry detergent solution (⅓ cup laundry detergent, ⅓ cup powdered household cleaner, one-quart of laundry bleach, one gallon of water)
  • Siding cleaning solution
  • Bleach solution
Heavy staining
  • Powerwash
Step 4: Clean it up. Use a soft-bristled brush to lightly scrub away mold and mildew stains for all solutions. A garden sprayer can be helpful in applying the various cleaning solutions to the siding. Follow directions on any siding cleaner or power washer.

Part 3 of 4: When to call a professional for exterior house cleaning

If you are worried about damaging your siding, simply do not have the time to do the cleaning, or have tried and the mold and mildew will not budge, there are many professionals that you can call.
Some places to locate a professional include:

Part 4 of 4: Tips to prevent mold or mildew problems on your siding

As the adage goes, “an ounce of prevention is worth a pound of cure.” Preventing damage can save you time, money, and effort in having to remove mold and mildew down the road. To do what you can to prevent the accumulation of mold and mildew on your siding, follow these tips:
Tip 1: Trim the trees and bushes. In general, regardless of the type of siding you have on your home, it is recommended to keep trees and branches away from your siding to limit moisture from causing damage, regardless of siding type.
Wood siding is especially vulnerable to damage from foliage, including birds who can rest on the branches and peck at the siding resulting holes, chips, and cracks.
Tip 2: Keep an eye on your siding. Monitor the problem and treat immediately. Take the time at least once a month, if not more often, to walk around your home and inspect it for any damage.
Immediately identifying the problem can help fix the problem before it grows and starts to damage the siding permanently, requiring replacement.
Vinyl siding will need more minimal care than wood or aluminum due to its durability. Occasional rinses and spot treatments for mold or mildew will keep vinyl siding looking good for years.
Wood siding requires treatment for prolonged life. Wood siding should be treated with some form of sealant, such as paint, stains, or a clear sealant.
Metal siding is going to be more prone to rust as well as stains. A coat of paint can help reduce the metal’s exposure to the elements and prevent rusting. If rust does occur, clean off the loose rust flakes and use some form or rust-inhibitor, such as a primer or sealant, before painting over the damaged area. This will help prevent the rust from spreading.
Tip 3: Wash your siding often. It’s best to do a quick scrub at least once a year in the fall to help prevent a mold or mildew problem. The start of mold and mildew issues can be difficult to spot until it’s a much larger problem, so preventive maintenance can stop a problem before it grows out of hand.
Keeping your home clean and well maintained not only helps with its general curb appeal, but it can make you as a homeowner happier and healthier, too. Keep mold and mildew at bay and immediately address any spots you see popping up.