5 Steps to Cleaning Composite Decking +Tips for Stains


Composite decking is quite possibly one of the best innovations in decking. Composite decksOpens in a new tab. have many benefits, from their durability and long-lasting qualities to their bug-resistant nature. But is cleaning composite decks an easy thing?

In short, cleaning and caring for composite decking is much less challenging than a wood deck. Not only do you get to skip some of the general care, but the cleaning routine is less rigorous and often.

So, let’s go through some general cleaning and care tips for composite decking. Then we’ll discuss how to remove stains from your composite decking and what areas you should be concerned about. Finally, we’ll go through certain chemicals and cleaning methods you should avoid when you’re cleaning composite decking. 

General Deck Cleaning

Manufacturers produce composite deckingOpens in a new tab. through a mixture of wood flour and a plastic compound like PVC. Since they don’t only consist of wood, you don’t need to keep up with standard regular wood care, such as:

  • Sanding
  • Sealing
  • Staining
  • Painting

The best part of composite decking is that those benefits last for the duration of the material, roughly 25-30 years. The only real care routine you need to concern yourself with is cleaning, which should be a cinch after you learn this method.

Let’s start by going through what materials you’ll need. Then, we’ll give you a step-by-step guide for how you can best clean your composite decking. Finally, we’ll go through specific cleaning conditions, like snowy weather.

Materials

You will need the following equipment to clean a composite deck:

  • Hose
  • Hose nozzle
  • Pressure washer (no greater than 1500 psi)
  • Fan attachment for pressure washer
  • Dishwasher soap
  • Bucket
  • Soft bristle brush
  • Soft bristle broom
  • Squeegee
  • Clothes

Optional:

  • Hose soap dispenser
  • Leaf blower

Weekly Cleaning Routine

Although this isn’t necessary, you should get into a weekly cleaning routine. That way, when the semi-annual composite deck cleaning comes around, it won’t be nearly as hard. And don’t worry, the weekly clean is more about decluttering than anything else. 

Start by sweeping off any light debris or dust from the deck. Doing this will help prevent any scratches or stains from forming on the decking. Then, hose off the deck to ensure that there’s no leftover dust or grime. 

Make sure you hose off everything. You might need to hose off areas more than once in some cases. When the water dries, it will leave a grimy film in some areas if you don’t.

Whenever you use the deck, you must clean food, grease, animal poop, or other wet messes immediately. These can leave stains on your deck that will get increasingly difficult to clean the longer they sit on your deck. If you let them dry, the problem will only get worse.

So, using a hose and a mild soap like dish soap, hose off any food or other wet messes from your deck. If a stain is forming, use a cloth and a soft bristle brush to get off any remaining discoloration. 

Once you get yourself into a weekly cleaning routine, it will be easier to keep your deck clean and maintained when the time arrives for a big clean. 

Semi-Annual Composite Deck Cleaning

Follow these steps when deep cleaning your composite deck.

Step One: Remove Dust and Debris

The first step is to clear off any dust and debris like you would during your weekly clean. So start by sweeping off the deck and hosing it off with fresh water. If you have a leaf blower, you can clear the deck with that. You don’t need to ensure the deck is spotless at this point because you’ll use a pressure washer to remove any stuck-on remnants.

Step Two: Apply Soap

You can either use a bucket filled with soapy water or a soap dispenser attachment for your hose for this step. Either option works, so it’s up to you which one you use. Just ensure you use dish soap since it doesn’t cause any damage to the composite decking. 

Once you choose a method, apply the soap to the deck. Wait a minute or two to allow the soap to degrease your deck. Don’t let the soapy water dry totally, as that can cause a dirty film to form on the deck.

Step Three: Pressure Wash

When using a pressure washer on composite decking, you need to be wary of a couple of things. First, the pressure can cause damage to your deck if you’re not careful. 

Different brands of composite decking can handle different levels of pressure. If you ensure you set your pressure washer to no more than 1500 psi, you should be safe. Before pressure washing, always check the manufacturer’s instructions for maximum allowable pressure.

The second thing you need to use is a fan attachment on your pressure washer. The fan attachment allows you to clean composite decking easier by making the water-jet larger and flatter.

So, after you apply soap to the deck and let it rest for a minute or two, it’s time to pressure wash. Using the fan attachment, position the end of the pressure washer no closer than ten inches from the decking. It will help protect the decking. 

Always remember to spray in a direction that leads off your decking. That way, you can easily remove any leftover debris instead of spraying it towards your home. Use the pressure washer on each plank or segment of composite decking to ensure you didn’t miss any spots. 

Once you’ve gone over every spot on your deck with the power washer, you should remove any large puddles of water that the power washer left on your deck. It’ll make cleanup easier and allow the deck to dry faster.

Step Four: Remove Any Remaining Stains

Although the pressure washer is a reliable tool for removing most imperfections from your composite deck, it doesn’t clean every spot. For the next step, start by locating any remaining stains or marks that the pressure washer didn’t remove.

Most composite deck planks have small textured finishes that make the decking less slippery. In some cases, dirt and grime can build up in these finishes. Using a bristle brush is the only effective way to remove the grime. 

Using soapy water and the soft bristle brush, clean off any remaining stains you didn’t clean with the pressure washer. This part will take some elbow grease, but hopefully, the soap, water, and pressure washer loosened some of the debris.

Step Five: Rinse Dry the Decking

For this step, you don’t need to achieve a bone-dry deck. Instead, this step is more about drying the deck before more dirt, dust, and grime form on the deck. Also, if you left any soap on the deck, it could leave a slippery film on the deck.

So, start by attaching the hose nozzle to the hose. It will give you slightly more pressure without having to worry about damaging the deck while rinsing. Once you connect the nozzle, hose off the deck, so all you’re left with is a wet deck. No soap residue should be visible.

Then, push the majority of the water off your deck using the squeegee. Although this will remove most of the water, you’ll still have some small, leftover puddles.

The best way to dry up these puddles is with a few rags. Allow the rags to soak up some water and then wring them out. Repeat until the deck is almost entirely dry. Only a few damp spots should be visible. The sun should dry these out without leaving a film.

Cleaning Composite Decking in the Winter

If you live in a snowy area, you know that cleaning your deck in the winter can be a real headache. When it snows, ensure you only use a plastic shovel to remove snow from your deck. If you use a metal shovel, you’ll scratch and damage your deck.

If you have ice build-up on your deck, it should be safe to use calcium chloride salt to melt and remove it. Remember to check with the manufacturer before applying salt, as it could potentially harm the integrity of the composite planks. Also, remember never to use colored salt, as it could stain your deck permanently.

As for cleaning your deck in the winter, the truth is it’s challenging. Once temperatures drop below freezing, cleaning your deck with water isn’t possible. The water would freeze before you have the chance to remove it.

That means your best bet is to clean your composite deck once winter ends. Once spring-time temperatures return, you can get right to cleaning your deck. Also, remember to remove and clean any small messes that may occur on your deck, like spilled food. It will help prevent stains, even in the winter.

Decking Stain Removal

Stains can turn into a real hassle. Whether you spilled some tomato sauce or some bird poop has sat on your deck for a while, stains are never fun. So how do you clean stains off composite decking?

Many types of stains can form on your deck. Let’s go through various kinds of stains and how to best remove them from your deck.

Tannin

Tannin stains form on your deck when dirt and debris get stuck on the composite planks. TanninOpens in a new tab. is an incredibly cumbersome problem when that debris builds up in the areas where two planks meet. The small gap can collect a lot of debris, making the stain harder to remove.

Start by using a hose to remove the debris. If the hose can’t remove all of it, use a plastic spatula to get in-between the cracks. Plastic has the least likely chance of scratching the surface of your deck. Ensure you remove all debris before moving on. 

You can use many products to remove these stains, from vinegar to bleach. Just remember never to mix chemicals when cleaning, even when you’re outdoors.

The best cleaning product for removing tannin stains is anything that contains oxalic acid. Commonly known as “wood brighteners,” oxalic acid products specialize in removing tannin stains. Always follow the product’s instructions so that your deck will remain in perfect condition.

Hard Water Stains

Hard waterOpens in a new tab. stains occur when your tap water is high in certain elements, such as calcium or lime. When you use hard water to clean, it will sometimes leave deposits of these elements on your deck. These deposits are most commonly white. 

Cleaning these deposits is only tricky because the water you’re using is hard. That means you need to clean them by hand without using any additional water.

The best way to remove these stains is with a rag and white vinegar. The acetic acid in vinegar is gentle enough not to damage your deck, but it will remove the stains. You have to rinse the deck after applying vinegar, so don’t use hard water. If your home only has access to hard water, boil it for ten minutes to remove some of the calcium or other elements. 

Animal Poop Stains

The most common type of animal poop that’ll end up on your deck is bird poop. Bird poop, along with other types of fecal matter, will cause a stain to form on your deck if you don’t clean it up immediately. 

Animal poop can carry harmful diseases, so always wear gloves to clean it up. Animal poop stains are generally easier to get off than other stains. Start by scrubbing it with warm, soapy water and a bristle brush. 

If that doesn’t work, rinse off all the soap and water. Once you rinse off the soap and water, allow the surface to dry. Then, apply vinegar and scrub with the brush.

Food, Oil, and Grease Stains

Remove food, oil, and grease stains as soon as you spot them. That way, stains won’t form, to begin with. But, if you wait too long, you’ll have to put in some work to remove the stain. 

In most cases, soap and water, alongside the bristle brush, will be enough to remove the stain. If that isn’t enough, use a mild household cleaner that contains hydrogen peroxide. It should help lift the stain from the decking. 

Mold

Mold can be a much harder thing to remove from your decking. Even though composite decking is mold resistant, mold can still form on the top of the decking. 

First, apply vinegar to the moldy area. Allow it to rest for an hour on the mold, which should kill most mold spores. Mop up and wipe away the vinegar. Finally, rinse the area with water and dry thoroughly. 

If that doesn’t work, you’ll need to buy a heavy-duty mold remover. You can purchase these at your local home improvement store. Always remember, never mix chemicals like vinegar and mold remover with each other.

Areas of Concern

Certain high and low-traffic areas on your deck are more prone to stains than others. One area that always seems stained is the area directly in front of the doorway to a deck. Since people are constantly walking in this area, it can become dirty.

Another area that often gets dirtier faster is any spot where eating occurs. When food touches your composite deck, it can leave a stain. Those stains will build up if you don’t clean your deck often, causing a dirty-looking deck.

If you have a dog or another type of animal that spends its time on the deck, check under their favorite spot for stains and dirt. As much as we love dogs, they bring dirt and dust everywhere on their fur.

Finally, you should be aware of spots with little to no use. Areas such as corners can have large amounts of leaves or dirt built up in them. Once dirt and dust build up in an area, it’ll inevitably begin to stain the decking. 

Cleaners and Chemicals to Avoid When Cleaning

Here’s a list of products you should avoid when cleaning a composite deck. As with any information in this article, verify that your deck can handle certain types of chemicals and cleaning routines by contacting the deck manufacturer. 

So, when you’re cleaning composite decking, you should avoid:

  • Metal cleaning equipment (metal-toothed brushes, metal shovels, etc.)
  • Super high-powered pressure washers
  • Ammonia
  • Bleach
  • Sodium hypochlorite 
  • Isopropyl alcohol (lower concentrations may be acceptable) 
  • Sodium-chloride or sand for ice melting
  • Oils
  • Paints, sealants, or stains
  • Wood fillers or putty
  • Other, non-manufacturer certified materials

Final Thoughts

Caring for a composite deck isn’t the hardest thing in the world, especially when you have access to all the tools and chemicals you need. If you recently purchased a composite deck, then gather all the products you need to clean your deck.

Once you’ve gathered all the products you need, you can get started with your weekly cleaning routine. Getting into this habit will not only make your deck look amazing, but it’ll help take a load off of your semi-annual cleanings.

So, if you have a composite deck and are worried about how tough cleaning composite decking is, don’t worry! Although there may be a lot of steps to remember, the pressure washer makes the whole thing a breeze. So, what are you waiting for? It’s time to give your composite deck the cleaning it deserves!

Ryan Nickel

A Red Seal carpenter, passionate about building decks to be enjoyed.

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