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How to Clean a Deck the Right Way

Cleaning a deck can seem daunting at first. What chemicals do you use? Do you even need chemicals? Can I pressure wash a deck? Do I have to use a brush? These are the questions that are likely going through your head. At one point, we have all had these questions going through our heads, professionals and DIYers alike. Deck cleaning seems complicated on the surface, but once you come to know your chemicals, types of decking, and how to clean each one, you will soon be proficient at this valuable skill. Get ready for a thorough, in-depth analysis on deck and wood restoration from the pros at Mount Pleasant Pressure Washing.

Deck Cleaning Solutions

Vinegar – Deck cleaning with vinegar is a common starting point for novice DIYers. It is safe to use, relatively plant-friendly, and you can find it just about anywhere. We recommend using vinegar as a neutralizer after cleaning with one of the chemicals below. All the chemicals below are "bases," which are chemicals that have a pH value higher than water, which has a pH of 7. The pH of wood is best kept around 7, so when you clean with a basic chemical, you need to follow up with an acidic chemical. The active ingredient in vinegar is acetic acid, which is an excellent neutralizer.

Even better than vinegar, however is oxalic acid. Oxalic acid is more potent than household vinegar, and it brightens wood decks in addition to its powerful neutralizing powers. It is not a common item found in big box stores but can be ordered relatively cheaply online from Pressuretek, a pressure washing chemical and equipment supplier.

OxiClean – Otherwise known as oxygen bleach, OxiClean’s active ingredient is sodium percarbonate. It creates hydrogen peroxide, an amazing plant-friendly cleaner best used on wood and other surfaces that corrosive chemicals would otherwise damage when added to water. Sodium percarbonate is our preferred wood deck cleaner. It is less likely to damage healthy wood fibers than other cleaners. We also buy this product from Pressuretek, but OxiClean powder can be just as effective.

Bleach – Sodium hypochlorite (SH) is the active ingredient in bleach. It is the most common cleaner used by pressure washing companies – it is highly effective at killing mold and algae, is cheap, and is readily available in large quantities. Bleach can be safely used on wood decking, but we prefer to use sodium percarbonate as it is a gentler cleaner. Wood can be sensitive, especially expensive woods such as Ipe or cedar. We do not want to dissuade anyone from using bleach to clean a deck, but we believe that over time if mild cleaners like sodium percarbonate are used, the wood will be healthier for longer.

TSP – Short for trisodium phosphate, TSP is a powerful paint and stain stripper, as well as an effective biocide to kill mold and algae. TSP is highly corrosive, and we only mention it because DIYers commonly recommend it. If you plan to do any paint or stain stripping, we recommend using sodium hydroxide (NaOH) instead of TSP. It is more plant and user-friendly, leading to less injury or damage to landscaping and painted surfaces. However, sodium hydroxide will strip paint, so be careful to cover any nearby painted surfaces with painter's plastic.

Deck Cleaning with a Pressure Washer

Power washing a deck is the quickest and most effective way to clean a deck. Important to remember, there is such thing as too much pressure. Applying cleaners to your deck before hitting it with the pressure washer and knowing the right pressure washing tips to use are the two crucial considerations before cleaning a deck. Later on, we will touch on the chemical side of things when explaining how to clean each type of decking. As far as pressure goes, any residential pressure washer from a big box store will work. When cleaning wood decking, use the 25-degree fan tip about 6 inches away from the deck. After applying your cleaners and letting them sit, start with the dirtiest area for a pressure test. Start with your pressure washer wand 12 inches away from the deck and slowly move it closer to the deck. You should be applying just enough pressure to dislodge the dirt, grime, and dead wood fibers. If you start to see furring in the wood, which is tearing up healthy wood fibers from the board itself, you are too close to the deck and damaging it. Be careful when releasing pressure from the wand, as the PSI is higher than when the water has been continually running through the wand (called burst pressure).

Deck Cleaning with a Brush

Deck cleaning can be accomplished with a brush, but it will take much longer than with a pressure washer, and the results will likely be subpar. A more feasible solution would be to clean the deck with a scouring pad attached to a pole. The scouring pad will be better at lifting caked-on dirt and grime from the deck.

Start first by applying your cleaners with a pump-up sprayer. Let them sit for the desired amount of time, scrub the deck in long streaks with the scouring pad, and cleaning the pad when needed. Rinse away any remaining debris with a garden hose, and then apply your neutralizer, letting it sit and keeping the surface wet. Rinse the neutralizer away, and now you have a renewed deck free of dirt and grime.

Does Deck Cleaning Need to be Done Before Staining?

Sometimes, a deck can look clean upon appearance, but it has a layer of dead wood fibers, invisible mold, and algae spores feeding on the deadwood and dirt caked to the boards. It is always a best practice to clean your wood deck with the appropriate cleaners, making sure to let the wood dry completely before applying any stain. If you choose not to clean the deck before staining, you can end up having mold and algae colonizing underneath the stain. Not only will this look unsightly, but you now must strip the entire deck of the stain to clean the wood and then reapply, causing yourself to spend unnecessary time and energy fixing such a simple mistake. Not cleaning the wood properly can accelerate rot formation, leading to hundreds to thousands of dollars of repairs.

How to Clean Trex Deck and other Composite Decks

A long-lasting, durable, and easy maintenance type of decking is composite decking, with the most popular brand being Trex Composite Decking. Composite decking looks strikingly like real wood decking without the hassle of routine cleaning and staining, and the boards are not susceptible to rotting like wood. Composite is great for busy families and professionals looking to minimize their time spent managing their outdoor decking.

We recommend using bleach and water to clean composite decking – but before getting started cleaning the whole deck – do a test spot with bleach straight from the bottle. Some generations of Trex decking and other brands of composite have been known to fail during cleaning with bleach. The color of the boards can change color during the cleaning process, which is an undesirable outcome for many. If your test spot with bleach straight from the bottle fails and looks different in color after rinsing, go ahead use Oxiclean or another sodium percarbonate-based cleaner. Here are the mixing ratios for cleaning with household bleach (5.25-6% sodium hypochlorite) and sodium percarbonate:

  • Household bleach: 1 gallons of household bleach to 1 gallon of water
  • Oxiclean: 1 cup of powered Oxiclean to 1 gallon of water
  • Sodium percarbonate: 4-8 oz of powder to 1 gallon of water

Regardless of which cleaning method you choose, for every gallon of solution you have, finish it off by adding 1 ounce of laundry detergent to the cleaner. This helps the cleaner stick to the decking and helps grab dirt and grime to be rinsed away.

Start by brushing or using a leaf blower to remove surface-level dirt and debris from the decking. Do your test spot, confirm which cleaner to use, and then apply your cleaner to a workable area of the deck. If using bleach, let it sit for 2-5 minutes or until you notice a color change in any algae and mold. Once killed, algae and mold should turn a brownish-tan color. If using OxiClean or sodium percarbonate, wait 10-15 minutes before rinsing it away. Use a garden sprayer with the jet nozzle, or use a pressure washer with the 25-degree fan tip. Damaging composite decking takes more pressure than it would take to clean wood decking, but damage can still be done. Using the 25-degree fan tip roughly 6 inches from the surface will allow for the dirt and debris to be lifted from the synthetic grain of the composite boards. Once dislodged, it can be rinsed with the 40-degree fan tip or a garden hose with the jet nozzle setting.

How to Clean Ipe Decking and Other Wood Decking

Brazilian hardwoods such as Ipe have become increasingly popular for outdoor decking and patios. They come in different colors of rich browns, tans, and reds, have an amazing lifespan and are easy to maintain. The boards are less susceptible to rotting than traditional wood decking and have a more sleek and modern appearance. For Ipe decking and wood decking, our preferred cleaning method is to use Oxiclean or sodium percarbonate powders. Many times, cleaning with bleach goes against manufacturer recommendations.

Start by adding 1 cup of Oxiclean per gallon of water, mixing thoroughly, and applying with a pump sprayer. The same can be done with 8 ounces of commercial-grade sodium percarbonate to 1 gallon of water. Both solutions should bubble up immediately upon contact with mold and algae. Let the solution sit for 10-15 minutes, misting the wood with your garden hose sprayer's misting nozzle. Fire up your pressure washer with the 25-degree fan tip attachment. Start by pressure washing about 12 inches from the surface, moving closer to the board until you notice the dirt and grime sloughing off the wood. This usually happens about 6-8 inches away with the pressure washing wand. Working in one direction from top to bottom, being sure to not get too close and fur the wood.

After rinsing thoroughly, it is time to add your neutralizer. Manufacturer recommendations are often oxalic acid, which can be ordered online and sometimes found in local chemical supplier stores and big box stores. We recommend wearing a respirator when using oxalic acid, as the fumes can cause lung irritation and other health issues. Mix 8-9 ounces of oxalic acid per water, and be sure to never add water to an acid; always add acid to water. Stir the solution until all the granules are dissolved and begin applying to the wood. Allow the neutralizer to sit for 10-15 minutes, keeping the wood wet with a misting sprayer. You can rinse the wood with a pressure washer, but there is no need to apply high pressure during this step, and you can get faster rinsing accomplished with your garden hose. Rinse each board a couple of times to remove all the oxalic acid.

Your results should look similar to those below: Years of dirt, mold, and algae gone, dead wood fibers stripped from the surface, and the natural color restored to the boards. Once dried, it is the right time to consider staining or oiling your wood, depending on what kind you have. Check out the next section to learn how to further protect your prized wood decking.

How to Protect Wood Decking by Staining or Oiling

Many homeowners choose to keep their wood decking void of any stain or oiling to preserve the "natural" look of the wood. Although this may seem tempting, not staining or oiling your decking can cause premature aging of your wood decking, leading to a dull grey deck instead of a rich brown color. The constant shrinking and expanding of the wood fibers during cooling and heating temperatures causes cracks and splinters in the wood, allowing mold and algae to begin colonizing in the wood, leading to even more deterioration. Not protecting your decking is a domino effect of damage and can lead to catastrophic dollar amounts worth of repairs.

Whether to stain or oil your deck is up to you, but we do have some recommendations based on certain criteria associated with wood decking.

  • Staining: Staining is like sealing a driveway or pavers – it provides a protecting coating on the surface of the wood. Some of the staining penetrates the wood, however, as wood is absorbent by nature. Staining needs to be done less often, lasts longer between coats, and protects the wood better than oiling. Staining is most common with standard wood planks and cedar.
  • Oiling: Oiling is like putting castor oil in your hair or butter on toast – you provide a naturally derived, carbon-based oil that hydrates the surface and keeps it from drying out. Oiling is required more often, lasts a shorter amount of time between coats (but does not need to be cleaned between coats), and provides a more natural method of protecting your wood decking. This is the manufacturer's recommendation for almost all kinds of Ipe decking.

We do not personally recommend anyone use a gas-powered sprayer to apply oils or stains – this is because it is common for DIYers to accidentally spray stain on their house, get leaks in their hoses, and have difficulty maintaining their equipment. You are better off either hiring a professional team or using a Deckboss stain brush. The Deckboss is 7 inches wide and can be screwed onto any standard broomstick. Whether applying oil or stain, start by covering any nearby surfaces with painter's plastic and taping around the edges. Place your stain or oil into a painter's tray, slightly saturate the brush, and begin applying even coats to your decking. Depending on the stain or oil you use, two coats may need to be applied.

Professional Deck Cleaning and Refinishing

If you are ready to save your wood deck and yourself a weekend of hefty laboring, reach out to our team at Mount Pleasant Pressure Washing to get on our annual wood restoration schedule. We work with clients across the Charleston area to provide exceptional and hassle-free deck cleaning and refinishing services. From wood cleaning, sanding, oiling, and staining, we do it all. Here is a recent wood deck cleaning we provided in Sullivan's Island, SC.


How to clean a deck the right way

The decking pictured above was cleaning with sodium percarbonate from Pressuretek at around 5 ounces per gallon. We pressure washed the deck with the M5 Twist nozzle, providing just enough pressure to remove grime and dead wood fibers. We followed up with oxalic acid, also from Pressuretek, at around 6 ounces per gallon. With the proper chemical application, pressure washing, and thorough rinsing, you can expect amazing results from just a bit of hard work.

If you have any more questions or concerns about wood restoration and refinishing, reach out to our team at Mount Pleasant Pressure Washing to get top-of-the-line industry knowledge on proper deck cleaning protocols. We are always happy to share what we have found over the years, spending hundreds of hours cleaning wood decks, log cabins, and wood playsets. Check out our intake form or calls us at (843) 471-0799 to get the best wood cleaning tips available from professionals.

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