How to Clean Fiber Cement Siding


Fiber cement siding has been developing a reputation of late as one of the most durable and low maintenance options for covering your home’s exterior. This extremely heavy and durable material is reinforced with sand, glass, and concrete to help ensure that it needs less maintenance and fewer replacements over its lifetime than wood, vinyl, or aluminum siding. Like any material exposed to the elements, however, it does occasionally need to be cleaned. Because your siding plays such a major role in your home’s curb appeal, it’s important that you remove any dirt or debris from your fiber cement siding as soon as you notice it. Thankfully, cleaning your siding is fairly simple no matter what substance may be on it.

Protecting Yourself and Your Landscaping

It’s important to remember that while fiber cement siding is easy to clean, you still need to take steps to protect yourself and your landscaping both from the debris that could be on your home and from the cleaners you use. Be sure to cover your landscaping with plastic sheeting before you begin. Wear protective eyewear, gloves, and any other equipment you may feel is necessary to help protect your skin, eyes, and lungs from any harmful materials that may come off your home during the cleaning process.

Remove Dirt and Debris

Depending on where you live and what kind of sunlight and exposure your fiber cement siding gets, you may find that the most common material you’re removing from your home is simply dirt and other natural debris. Sand, mulch, soil, and other materials may collect on the sides of your home, having been blown there by strong winds or pushed there by drifts of snow.

Because fiber cement siding has a natural-looking wood grain, some of this debris may collect and stick to the siding over time. It’s easily removed, however, and requires no special equipment or cleansers.

Use a medium-bristled brush to remove any of the loose particles from your siding. You may want to brush in a few different directions to help free any dirt that gets trapped in the boards. Once you’ve gotten the dirt loose, use a garden hose to rinse the siding and remove any left behind stains. You can let your siding dry naturally once you’re done.

Removing Oil and Grease

If you’ve been working on your car’s engine close by the house and have gotten oil or grease on your siding, this is easy to remove with a soft cloth and some gentle cleansers.

Dishwashing soaps with a neutral PH such as Dawn or Ivory liquid are perfect for use on your fiber cement siding. Mix up a solution of plain water and liquid dish soap and apply it to your siding with a soft cloth. Do not use abrasives to try to remove the stains; let the soap break it down for you while you rub with the cloth. To rinse, simply use a garden hose to remove the soap and grease residue once you’re done.

Removing Mold and Mildew

If you live in an area that has a lot of shade, you may find mold or mildew growing on your siding. You may also find black streaks caused by blue/green algae spores which are commonly blown onto houses by the wind. While unsightly, these are fairly easily removed from your home and your fiber cement siding.

Mold, mildew, and algae can all be killed by either lowering or raising the PH on your siding. You can do this in a few different ways. Chemicals and sprays aimed at killing mildew are suitable for use on your fiber cement siding. Simply spray your siding, allow it to work for several minutes, then rinse with a garden hose.

This is not advisable for repeated applications, however, as the highly acidic solution could eventually begin to damage the finish on your siding. So if you find that algae, mold, or mildew is a recurring problem, you may want to use a substance that lowers the PH on your siding instead. This could mean using:

- Bleach

- Ammonia

- Salt

- Baking soda

Use only one of these materials at a time, mixing it with a solution of plain water, and use a pump sprayer to apply to your siding. Allow it to sit for several minutes, then rinse with plain water. For extremely stubborn stains, you may need to agitate the solution on the siding using a soft bristled brush; do not use abrasives on the siding to remove the stain. Repeated applications of the cleanser may be necessary for extremely large or dark mold or mildew stains.

Keep Your Siding Looking Great

Fiber cement siding needs little to no upkeep beyond regular cleaning to keep it looking its best. Remember that your siding plays a major part of your home’s curb appeal, and that you should clean off dirt, debris, or stains as soon as you notice them. Take care of your fiber cement siding to keep your home looking great for years to come.