Powerful Guide On How To Remove Black Stains From Wood Deck

Powerful Guide On Causes & Tips On How To Remove Black Stains From Wood Deck

Does your wooden floor or deck appear as if it has been plagued by unwanted decorations straight out of a horror movie? Exaggeration aside, this is a common issue that many wood deck owners face because of naturally occurring causes. Fortunately, common problems usually have solutions, thanks to how familiar people have become with them. 

In this article, we will explore these solutions to help you understand how to remove black stains from wood deck, which can potentially erode the wood itself. We will provide information on everything you need (as well as the budget-friendly alternatives you can opt to use instead) and the cleaning process. But first, let us talk about the root of the problem or the causes of this common issue.

How To Remove Black Stains From Wood Deck

What To Prepare

Most of the equipment we will mention is quite common. Some might even be available without leaving your home. As such, we will provide the most effective options and the more budget-friendly alternatives you can substitute instead:

A cleaning agent 


The best cleaning agent you can use would be wood cleaners. Most commonly, people with wooden decks would keep a supply of oxalic acid around to combat these black stains when they start appearing.

However, you can also use some products that are most likely already in your home, such as bleach, detergent, baking soda, and vinegar.

A cleaning agent that is specialized in wood would be your best choice. But since not everyone can access those products (especially if you urgently need to get rid of the black stains), you can use some common alternatives in place of wood cleaner.

The most effective alternative would be bleach, thanks to its high corrosiveness, which can be utilized against microbes, which include fungi. When using bleach or detergent, you may want to use the protective equipment we will discuss later since they can also harm you if used carelessly.

Baking soda, together with vinegar, are some of the staples for being alternatives for an abundance of cleaning agents. In terms of effectiveness, vinegar is often better than baking soda for removing black stains since it is more corrosive. 

Pressure washer, scrub brush, or a scrub broom.

These are the tools you would use in the cleaning process, essentially carrying out the cleaning agent and the water to use. Pressure washers are powerful as they exert a lot of force once they release the water, which easily eradicates dirt.

These are the most efficient methods to get rid of the black stains in a shorter amount of time. However, one downside is that some pressure washers can be costly, specifically if you desire something of high quality.

Using a scrub brush or broom instead can be much more tedious and straining than the top choice. Imagine having to scrub away on the deck through thick layers of fungi; it is not efficient, nor is it pleasing for most people. Though this is the cheap and traditional way of cleaning wooden decks if you choose to use scrubs, clean more frequently so the fungi will not build up over time. 

Protective equipment (optional)

When using a scrub brush or a scrub broom while also using bleach or detergent, it is recommended to put on some safety equipment. Gloves will usually do the work, but you can also wear a face mask if the scent of bleach easily irritates your throat or nasal area. For some people, exposure to bleach can cause unpleasant effects on their skin, which can lead to breakage and irritation. 

Meanwhile, scrubbing for extended periods can eventually cause the friction from the action to take a toll on your palms. Wearing cleaning gloves can reduce the amount of damage the friction can do by acting as a protective layer between your palms and your cleaning tool.

A whole lot of water

Water is essential to clean the mass of fungi on your wooden deck. It washes away the dirt and the remains of the fungi that had been exposed to the cleaning agents. However, you may wonder if it is a good thing that you are adding water to the process when fungi thrive in moisture. 

The answer is simple; fungi take some time before they can cause the black stains to appear. Since you are essentially getting rid of the fungi through cleaning, the wet wooden deck becomes a blank slate where there are little to no fungi left.

Naturally, you would want to clean the floors again in the future, but controlling the number of fungi propagating on your deck is the key to preventing any further damage.

Removal Process

Below is a procedure on how to properly get rid of the black stains:


Mix one cup of the cleaning agent into one gallon of water. The amount can vary based on the size of your wooden deck and what type of cleaning agent you are using, as some options like vinegar are much more soluble.

Allow the cleaning agent to dilute in the water for a couple of minutes to ensure the whole gallon of water is mixed with the cleaning agent. If you are using a pressure washer, add the water and use the ejector to soak up the cleaning agent. 



Dip the scrub of your brush or broom into the mixture and start cleaning. Make sure to scrub the wooden deck thoroughly and to dip the scrub constantly to ensure that the fungi are being eradicated as you clean.

For pressure washer users, spray away at the wooden deck and make sure not to miss any spots on the edges that may contain small spots of the black stain.

For black stains that are difficult to remove, try pouring a little bit of the mixture into the area and apply force while scrubbing or spraying. If the pressure washer is not doing the trick, then resorting to scrubbing forcefully can be done instead. 


Once the wooden deck has returned to its original color, you can try rinsing the remaining mixture away with more water. Some cleaning agents like bleach can cause damage to the wood if it remains there for an extended period. You should ensure that there is no excess bleach or detergent, which can be easily seen as it often produces a bubbly puddle of water. 


If your wooden deck is indoors, you may want to open your blinds, windows, or your door for the wood to dry up properly. Since fungi can quickly propagate if the wood is being stored while still wet, the lack of air or sunlight inside your house can emulate this condition. Ensure a steady airflow so your wooden deck can dry up faster.

Stain Prevention

Unfortunately, the conditions required for fungi to not propagate are hard to achieve, especially if it is inside of your home. The best method is to clean your wooden deck constantly to ensure that the fungi will not form black stains. This can be done annually, but you must use the appropriate cleaning agent, the wood cleaner. 

Wood cleaners can thoroughly clean your wooden deck without damaging the material. The best conditions for this cleaning session should be in the spring season as it will not be too hot to the point where the wood cleaner would evaporate faster. 

“Why the spring season?” you may ask. Well, since fungi cannot grow in the winter season and instead plant spores that can eventually grow during other seasons, it is best to eradicate them before they propagate. Since the upcoming season after winter would be spring, getting rid of the fungi in the season of their growth is an excellent choice to ensure they will do little to no disturbance.

Final Words

Black stains on a wooden deck are not a pleasant phrase for most wood deck owners. Following our steps mentioned above, your wood deck stains should be taken care of.