How to Clean a Wooden Deck [Remove Mold and Mildew]

Wooden decks are one of the best installations in a home. When taken good care of, wooden decks can give years of service without the need for repair and maintenance. It is one of the spots you can hold a small evening party or just relax as you unwind from the long day’s events in the evening.

The wood on your deck takes a lot of beating from the weather. During the spring, the wood is frequented by leaves, flowers, and all sorts of organic matter from the trees shedding most of their leaves.

Then comes the heavy ice presence during the winter months. If the organic matter stays for long without being removed, it will rot and encourage the growth of mildew and sometimes mold. Mold and mildew on wooden decks do not only cause wood rot, but it causes accidents due to the slipperiness. Let’s look at how to clean a wooden the right way.

NOTE: Always protect yourself when dealing with mold. While cleaning, wear goggles, rubber gloves and a face mask that covers your nose and mouth to avoid any contact with mold.

How to Clean a Wooden Deck

Cleaning a wooden deck is quite involving as compared to cleaning a composite decking. Wood is a naturally absorbent material that can warp or decompose when exposed to water a reason as to why a protective sealant is applied afterwards. The following are easy steps for cleaning a wooden deck

1. Remove everything from the deck

To have a clear view of the whole floor space and ensure that no spot is left dirty, begin by removing everything from the deck. This includes the furniture, flowerpots, and everything else that might be on the deck floor.

You might want to secure a large cloth to cover the furniture and flowers on pots; this prevents them from picking so much dust when sweeping the deck in later steps of the process. Some furniture and flower pots may be too big or too heavy, which means you might need a helping hand to remove them.

Not unless you are very confident and the flower pots are very small, do not remove them all by yourself. You do not want to solve a problem while creating another on the other end.

2. Sweep the deck

Pets and our feet will always pick dirt and transfer it onto the deck wood. Winds can also carry dirt and debris and deposit on the deck wood. It, therefore, means that the deck wood can have a lot of dirt and debris on its surface. To get rid of the debris and most dirt, sweep the surface using a broom.

3. Inspect the deck

Some deck wood may warp when it sucks a lot of rainwater and ice. This is very common especially when it is unsealed. The inspection helps you spot debris that may be trapped in the spaces between the boards. It also helps you identify whether or not if your wooden deck needs a new fresh sealant.

When wood contracts and warp in the intense summer heat, dirt and debris may be trapped there and cause wood rot. At the same time, some dirt may be deposited in the gaps when sweeping.

To remove the debris and dirt trapped in the spaces, use a spatula or putty knife to widen the gaps and use a hard brush to raise it.

4. Spray the deck with a water hose

You will find that even after sweeping, some debris and dirt will still not come off. To get rid of most of the dirt and debris, spray water on the deck with a water hose.

The water helps by loosening the dirt debris to make the cleaning easier and faster. To remove the dirt debris even faster, press the nozzle of the water hose to create some pressure.

5. Apply a cleaning solution and scrub

For the common dirt and debris, add a cup of dish soap to one bucket of water. Then use a broom to spread the solution across the surface and let it sit for about 20 minutes. This allows the solution to act on the debris.

For a deck wood covered with mold and mildew, pre-rinse the surface with a pressure washer to remove the large amounts of mold and mildew. Then mix a cup of white vinegar to one bucket of water and use a broom to spread the solution.

Then sprinkle a few spoonful’s of baking soda on the surface and let it soak the dirt for 20 minutes. I know by now you are wondering why you should use the powdered baking soda instead of mixing it with vinegar and water. Powdered baking soda is more effective than the solution form.

Mold can develop on almost any structure material. Probably the greatest advantage of the present covered and shell-supplied composites is that shape has no natural material to develop on, and hence can’t stain the decking similarly it could with original composite items.

Use a hard brush to thoroughly scrub the surface for a clean finish. Ensure to follow the direction of the grain to avoid damaging the wood. But if the wood has a sealant, you can scrub in circular motions.

A hard brush means you will have to bend over, and this might be too tiresome for you if you at some point, especially if your deck is too big. Instead of a hard brush, you can use a broom to scrub the surface. Ensure to start from the point where the deck attaches to the main house and work your way across the deck.

6. Rinse the deck thoroughly

Being sure that the dirt, debris, and mold and mildew are now gone, use a pressure washer to rinse the grime off the surface of the deck. A pressure washer is the best because the thin water streams will not soak the wood, something that may otherwise cause wood rot and warping.

As you rinse the deck surface, ensure not to bring the nozzle of the washer too close to the deck surface. Water streams from a pressure washer come at a very high pressure, which may damage the wood sealant when the nozzle is too close to the surface. The pressure washer wand should be around 12 inches above the surface of the deck.

With this in mind, you should run your pressure washer at a lower pressure setting of between 500 and 600 PSI. Rinse the deck along in the direction of the wood grain and ensure to overlap each board to ensure no spot is left untouched.

7. Air-dry the deck

Use a broom to sweep most of the water left on the deck surface. Depending on how hot is; the deck will take between 2-3 days to air dry. Air drying is the best if you want to get rid of all the water and prevent the growth of mold in the future.

To ensure a faster and complete air drying, schedule the cleaning on a hot summer day. Also, avoid stepping and keep the pets off the deck when it is drying. Doing so would only stain the deck again since it is still wet.

8. Run a water test

Applying sealant on a wet wood does not solve anything; on the contrary, it only makes the situation worse. This is because the water trapped in wood may cause warping and wood rot. To prevent this scenario, a water test is best to determine whether or not deck wood is ready for a new fresh sealant.

Pour a cup of water across the deck surface and observe how it behaves. If the water is absorbed into the wood within the first 30 seconds, then it means the wood is dry and ready for another sealant. If it takes longer to be absorbed, then the wood is still dumped with water and is not ready for another sealant application.

9. Apply a new sealant

Replace the old deck wood boards with new and seal the wide crevices and gaps between the boards. Depending on the extent to which the sealant has been damaged, it is now time to apply a new sealant.

An old and worn out wood sealant leaves your deck wood vulnerable to weather elements. Expansion during the hot summer months and contraction in the winter months causes warping and this reduces the longevity of the deck.

To apply the sealant, use a brush to spread finish over the surface, following the direction of the grain. A good sealant protects the wood against adverse weather while giving your deck a new look like it is new all over again.


Regular cleaning your deck is important for your quality of outdoor fun. The best thing about cleaning your deck with vinegar is that it also works by keeping flies away so that you can enjoy your outdoor parties in peace.

Having done all that, then return the furniture and flowerpots to the deck. Consider changing the arrangement of the flower pots and furniture every time you clean your deck. This works by bringing in a new setting and this breaks the monotony so that you can enjoy your outdoor moments even better. Invite your friends over and have fun at your fresh clean deck!

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