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How to Clean Fiber Cement Siding (2024 Guide)

Written by Ashlyn Needham , Edited by Gianna Cappuccio

Published on September 26, 2024

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How to Clean Fiber Cement Siding (2024 Guide)

Are you tired of the eyesore that is your dirty fiber cement siding? If your home needs a wash, here are the steps you need to follow.

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Fiber cement siding is one of the strongest materials you can have to protect your home. Not only does the incredibly durable material come in fabulous color choices to please the eyes, but you can also expect this material to be around for the long haul. Even though fiber cement siding features amazing benefits, like being able to withstand the strength of powerful storms, it’s not invincible to the occasional dirt, grease, grime, or even mold and mildew. 

Does your siding look a little dingy? If it’s time to revitalize your home’s exterior, we’re happy to say that cleaning fiber cement siding is fairly easy and a great DIY project (unless you have some hard-to-reach areas). Here’s how to clean fiber cement siding, what products work best for this material, and when to call in the help of a nearby professional.

Hire a local pro to clean your fiber cement siding

What cleaners are safe for fiber cement siding?

When you clean your fiber cement siding once a year, the products you use matter a great deal since they can negatively affect the overall design and performance of your siding. You want to protect your lavish new boards, so fiber cement material needs to be kept free from harsh or abrasive chemicals. It’s said that the best cleaners that are safe for this siding are those that are targeted towards mildew removal.

Unless you’re making a homemade cleaner (which only needs liquid detergent, water, and TSP), here are store-bought cleaners to look for that come with a green light to use:

  • Jomax

  • Mildew Check 

  • Mold Armor

  • Oxy Solve

  • Krud Kutter

How to clean off dirt or grease

If you need to clean off dirt or grease that’s stuck on your fiber cement siding, then you’ll need a simple cleaner that you can make yourself, and no extra products are needed! You will, however, need a soft cloth or bristled brush to work the cleaner onto the surface as you follow these instructions:

  • Mix together water and detergent in a large bucket.

  • Dunk a soft rag or soft bristled brush into the cleaning solution.

  • Start scrubbing at the dirty or grimy areas.

  • Rinse off the cleaning solution with water from your garden hose.

If dirt or grease persists after cleaning, you may need to repeat steps two through four until the dirt is fully removed. 

How to clean off chalk or dust

Have contractors been working at your home lately? The good news is that when it comes to cleaning off chalk or dust on your fiber cement siding, all that’s really needed is water. Use your garden hose to gently rinse the light particles off the side of your house. If any of the material is truly hard to remove, you can use the cleaning solution from the previous step to help. 

How to clean off mold or mildew

It’s impossible to keep your home from developing mold or mildew, but the good news is that if it’s caught early enough, it’s easy to remove yourself.

When cleaning off mold or mildew from siding, wear safety goggles and gloves as you use the following cleaners. Of course, you can use a store-bought cleaner that’s specialized to tackle mold and mildew while remaining safe enough for fiber cement siding, but if you want to make a homemade rendition, you can use the following products:

  • Bleach

  • Baking soda

  • Ammonia

  • Salt

Using one of these products, spray it onto the affected area before rinsing it off with water from your garden hose. If simply rinsing won't do the trick, you may need to use a soft brush or cloth to work the product into the areas. 

More fiber cement siding cleaning tips

A yellow sponge being rung out into a blue bucket with soap and waterOne of the perks of fiber cement siding is that, compared to other siding materials, it does not require as much upkeep or maintenance – but that doesn’t mean it should be neglected.

Here are some other tips to keep in mind for cleaning and maintaining fiber cement siding:

  • This siding type should be cleaned at least once a year. 

  • When cleaning, start at the top and work to the bottom in small sections. 

  • Avoid using harsh chemicals at all costs. 

  • Never use a pressure washer on this siding type. 

  • Inspect caulking once a year and reapply as necessary to keep your siding moisture-free.

  • If you find any significant damage, contact a professional immediately. 

Should you DIY cleaning your fiber cement siding or hire a pro?

Cleaning your home’s siding material is a pretty straightforward process that can be done DIY style, but there are a few times when calling in professionals can be a major help. For instance, professionals can get the job done if you’re having trouble reaching areas that are way up or hard to reach. If you find the spots you’re cleaning unrelenting, it might be best to call in a professional.

Get a quote from a professional siding pro

Fiber cement siding frequently asked questions

You can use two types of cleaners to clean fiber cement siding. The first is a homemade cleaner mix that consists of mild liquid detergent and warm water. You can also sprinkle TSP in the solution to boost the cleaning agents. You can also look for a specialized house siding cleaner free of harsh or abrasive chemicals. Chemicals can damage the aesthetics and performance of the siding, so the best type of store-bought cleaner for this project is something like Jomax, Mildew Check, or MoldArmour.

It is not recommended that you power wash fiber cement siding since it can damage the material. Instead, it’s best to use your cleaner with a soft-bristled brush to scrub the cleaning solution in before rinsing it off with your garden hose, as garden hoses have a much gentler pressure that won’t damage the siding.

Regular inspections and washing are the best way to maintain fiber cement siding. Since damaged siding can compromise your house's underlayment and foundation, you must check your siding for damage several times a year or after major storms. That way, you can hire professionals to make necessary repairs once something is caught so your house stays structurally sound. Also, regular washing is crucial for keeping your fiber cement siding. Washing off dirt and grime keeps your siding aesthetically pleasing but allows you to prevent the build-up of mold or mildew, which can cause more problems.

Written by

Ashlyn Needham Content Specialist

Ashlyn is a freelance writer with 8 years of experience writing interior design, DIY, and renovation content. Her work has appeared in multiple publications including The Spruce, Southern Living, House Beautiful, Fixr, and more.