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How to Prevent and Remove Mold from Cedar Siding

Black mold – we have all seen wood sided homes that turned an unattractive moldy color, it just looks bad. The problem is that for years many oil-based stains did not have proper mildew-cide. 

Oil, in and of itself, will actually feed mold. It needs to contain a proper mildew-cide (chemical agent that kills mildew while preserving the oil particles that protect the wood).

The reason we love oil is because nothing does a better job at conditioning and preserving the beauty of wood.

Black Mold on Western Red Cedar Siding
Black Mold on Western Red Cedar Siding

Learn how to remediate mold on your wood siding - both removing mold and then preventing mold from returning.

How To Prevent Mold from Forming on Your Cedar Siding

As wood siding experts, the first step to long-term performance is stain selection. In today’s market, due to environmental restrictions, we must be careful that the stain we select is a penetrating stain.

We recommend contacting the technical support department of any stain you are considering and asking what the refinishing requirements are when it’s time to maintain the wood. 

Some stains require harsh chemicals and 100% molecular removal of the existing stain in order to refinish, while others require a simple wash/scrub combination and heavy rinse to refinish.

The labor difference between these two methods is significant enough to consider the cost of each and then make an educated decision.

The next big decision is factory finishing. Once you determine you have a penetrating stain it’s important to find out whether or not that stain can be applied by a factory finishing machine.

If you use a penetrating stain on the first coat at the factory, you can probably get away with a less expensive stain that may not last as long but will work in a factory finish machine. 

The benefit of the machines is a finish on the back, both sides, and the face, which provides you a complete seal on the board but does not necessarily require the most expensive stain in the marketplace.

factory finishing wood siding

Once you have a six-sided seal on the wood and you install, in about a year or two it’s time to do maintenance. 

If you have used the penetrating stain, you have the option of using any stain you would like on the first maintenance cycle.

A film-forming or water-based stain, in many cases, will not allow you to apply an oil or resin-based penetrating stain afterwards. The film-forming particles will not allow an even penetration.

We recommend a product called DEFY.

They have created a synthetic, resin-based stain that will penetrate very well. It will not feed mold and provides an excellent protection for your wood investment.

Also, minimize the amount of mulch you add around the perimeter of your house and wood siding, as this can also encourage mold growth on your wood siding. 

The key is do not wait. If you start to notice discoloration, appearance, or evidence of mold, it’s time to clean your wood siding.

Don’t wait until your wood siding looks like this!

mold forming on wood siding
Mold forming on wood siding

How To Clean Mold Off Cedar Siding

First things first, do not pressure wash your wood on a high pressure setting it can permanently damage your wood. Secondly, do not clean your wood mold with Chlorine Bleach, it will eat the fibers and discolor your wood siding.

Check the wood cleaner product label for the chemical name for chlorine bleach, sodium hypochlorite.

For more in depth instructions on how to clean your wood siding, read our guide on How to Clean Cedar Siding in Just 4 Steps

  1. Clean your wood siding with water.
  2. Apply Oxygen Bleach.
  3. Apply Oxalic Acid.
  4. Re-stain your wood siding.
Cedar Siding Home After Mold Removal
Cedar Siding Home After Mold Removal

Just remember that 99% of all reported siding problems are installation and maintenance related. If you take care of your wood- it will take care of you. If you're interested on hearing a customer's experience with wood siding prevention and removal, visit our Buffalo Lumber Community page to read our case study and gain expert field advice on wood siding mold removal.

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