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How to Clean Cedar Siding in 4 Easy Steps

How to Clean Cedar Siding in 4 Easy Steps - Cedar Siding Maintenance

Learn how to clean and prep cedar siding using oxygen bleach and oxalic acid (always follow manufactures recommended instructions, this is a guide only). This is a great read if you're looking to learn how to prevent mold from forming on your cedar siding. If you’re looking to buy cedar siding but first want to learn about cedar siding maintenance so that you can better understand the cedar siding pros and cons, read on, because understanding how to maintain cedar siding is an important part of the equation!

We recommend that you follow these four steps to clean and prep your cedar siding.

Clean cedar siding with water.

The first thing to do is to remove any dirt or organic material from your cedar siding. Use either a pump sprayer or a power washer for this. If you use a power washer, use a nozzle that hits the full width of the wood siding board, so the pressure is diffused.

Hold the power washer no less than 6 inches and at an angle no fewer than 15 degrees so that you will not be creating pockmarks on the wood siding.

WARNING: When using a power washer, having the pressure up too high has caused more wood to be ruined beyond the point of repair than any other single thing I have seen in my career. If you’re going to pressure wash you have to be extremely careful of the pressure itself. The pressure level used must be significantly lower on wood siding.

Apply Oxygen Bleach.

Next, apply Oxygen Bleach to your exterior cedar siding to neutralize the organic material. I recommend the brand STAIN SOLVER for two reasons. It has the most active ingredients and also is 100% made in the USA. Other brands made overseas use quite several filler ingredients that don't do anything needed.

Follow the instructions and mix it into a bucket or sprayer before applying it liberally on the wood siding. The direction when applying should be from the bottom up.

With the solution in place, scrub the cedar siding from the top down to prevent streaking. Leave the solution on the wood siding for about 15 minutes, keeping it wet. Once cleaned, rinse thoroughly.

A before and after application of oxygen bleach:

Before Application
Before Applying Oxygen Bleach


After Applying Oxygen Bleach
After Applying Oxygen Bleach

Apply Oxalic Acid

I have not encountered a specific brand of Oxalic Acid that sets itself apart from the rest so just go with any recommendations by your local paint store. If I find one, I'll give an update so be sure to regularly check out our websites Buffalo Lumber and  Buffalo Lumber Community and connect to us on social media to receive more tips.

Apply the Oxalic then observe your cedar siding. If you are not getting the results you want, hit it again. Keep doing it until you are satisfied with the cleanliness of the wood. Once you are, rinse. It is important to remember to rinse, rinse, rinse when you are using chemicals. And just when you think you are done rinsing, rinse again.

Once the moisture content reaches 15%, your exterior cedar siding is ready for stain. To measure the moisture level, use a moisture meter which is available at the local hardware store.

After applying Oxalic Acid:

After Oxalic Acid Application
After Oxalic Acid Application

Finish by re-staining the cedar siding

When selecting the right stain to use, make sure it can achieve the right level of penetration so you can use the steps above for the next time you clean your cedar siding. The wrong type of stain means that you will need to use strippers for the next cleanup.

Strippers contain hazardous chemicals that are difficult and laborious to clean up, while also bad for the environment. We recommend Defy Oil-based Wood Stains because it can be cleaned using Defy's environmentally friendly wood cleaner. But regardless of the brand, it is always a good idea to contact the tech department and ask for their recommended cleanup process and possible labor cost. Also, every state has different laws of what they can or cannot sell with stains based on their chemicals contents.

Once the stain is ready, apply it following the orientation of your wood siding board. For vertically oriented siding, stain from the top-down, doing the entire course, without overlapping the stain on any given area. This will allow you to manage drips and streaks. For horizontally oriented sidings, start from the top corner and then go all the way across.

After re-staining:

After Re-staining with Timber Ox
After Re-staining with Timber Ox

To recap how to clean cedar siding:

  • Make it a habit to inspect your cedar siding annually, If there is an issue, you should address it as soon as you can. A little 2-hour labor now will save you time. Waiting for another year might worsen the problem and you will be spending more time and money in the process.
  • Clean the wood siding with water from the bottom up, apply Oxygen Bleach from the bottom up, scrub/rinse the solution from the top down. This way, the cleaning agent will be able to do its work without leaving any streak marks behind.
  • Condition your cedar siding using Oxalic Acid. Oxalic acid restores the PH balance of the wood siding, making it ready to accept the coating of stain so it can adhere properly.
  • Rinse, rinse, rinse and then rinse again. Thoroughly rinse between each application of Oxygen Bleach and Oxalic acid to keep everything healthy and clean.
  • Choose your stain carefully. Contact the tech department of the chosen stain and ask about the cleanup process for re-finishing.
  • Stain from the top down. Control drips and streaks by staining in continuous motion and avoid overlapping.

And there you have it, wood-lovers, straight from the Buffalo's mouth. Remember to follow this guide and enjoy your well-maintained cedar siding.

Let us know how this worked for you and tag us in your social media posts! And if you need help with your cedar siding project, contact us here.

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