Composite Decking: How To Clean, How Often To Clean, and What Cleaning Products Work Best

January 25th, 2023 | by Jim Gates

how to a clean composite deck

Whether it’s sunbathing, having the family over for a barbecue, or curling up in a comfy chair reading a novel — you love spending time on your new composite deck. 

But it’s starting to look a little grimy, and you’re wondering just how to go about getting it back to its former glory. 

If your composite deck is in need of a bit of tender loving care, you’ve come to the right place. 

We’ve got the details on how to clean composite decking, including how often you should clean and the best products to use to keep your deck looking its very best.

Table of Contents

How To Clean Composite Decking: A Step-by-Step Guide

Step #1: Prep the Deck

The first thing you’ll want to do to clean composite decking is to clear off your deck. Remove: 

  • Tables
  • Chairs
  • Rugs
  • Grills
  • Planters

It’s also a good idea to prepare the surrounding area by covering anything you don’t want to get cleaner on, such as nearby:

  • Shrubs
  • Grass; or
  • Yard ornaments. 

Step #2: Mix Your Cleaning Solution

Using a bucket and warm water, mix your cleaning solution. 

Depending on the type and amount of dirt and build-up on your composite decking, you may choose to use:

Step #3: Use a Soft Broom or Deck Brush

Next, it’s time to start scrubbing.

In most cases, a soft broom, handheld brush, or long-handle deck brush should get the job done. For hard-to-remove spots, however, a handheld deck brush may be your best option. 

Apply the cleaning solution directly onto the deck and scrub gently, but thoroughly.

And be sure to brush the surface of the deck along the length of the grain of the board. This ensures that all traces of dirt and debris are removed from the expansion gaps between the boards.

Step #4: Scrub Stubborn Spots First

Knock out any especially dirty areas first. 

This includes spots of :

  • Tree sap
  • Caked on dirt
  • Grease or oil
  • Hard water deposits like lime, calcium, or silica

Check for grime that may be stuck in the grooves and around the edges of your deck, and be ready to put in a little elbow grease, if necessary.


Step #5: Get Rid of Mold and Mildew

Next, you will want to tackle any mold or mildew on your composite decking. 

These must be cleaned using a specialty cleaner that will not only kill the spores but also prevent the growth of any additional mold.

A product such as Mold Armor E-Z Deck, Fence, and Patio Wash makes quick work of cutting through those unsightly splotches of mold and mildew. And since it’s a bleach-based product, it kills mold, cleans, and brightens your composite decking without scrubbing. 

Just be sure to do a test run and apply a small amount of cleaner to a hidden or out-of-the-way spot before you begin to ensure it doesn’t discolor your composite deck boards.

And rinse extra thoroughly once you’re done to remove any excess cleaner.

Step #6: Spray Entire Deck With Water

You’ve gotten rid of the stubborn spots, mold, and mildew. 

The next step in getting your composite decking sparkling clean is to wet down the entire deck in preparation for scrubbing the full areas with soap.

Step #7: Clean and Rinse the Deck

Using your pre-mixed solution, begin to clean your deck. 

If the day is sunny and hot, just do a small area to avoid the solution drying as you go. Otherwise, you can cover the entire deck with cleaner and scrub away.

Don’t forget the final rinse!


composite deck how to clean


How Often Should You Clean Your Composite Deck

If you’re serious about keeping composite decking nice and clean, you’ll want to get rid of dirt and stains as they appear. 

Are you watering your newly-planted flowers and accidentally splashing dirt onto your deck? Wash it off right then and there.

You move a chair and notice water deposits underneath? Clean them right away.

You’re rearranging the flower pots and notice mold growing underneath? Treat it now, so it doesn’t become a bigger problem that’s harder to clean down the road.

If you keep up with dirt as it appears, you should be able to keep it looking its best by cleaning composite decking once in the spring and once in the fall, with a bit of spot cleaning during the summer. If not, you will want to wash it down once a month.

What Is the Best Thing To Clean Composite Decking With?

At Three Rivers Custom Decks we recommend Simple Green Deck and Fence Cleaner. You can use a soap product, such as Dawn dish soap, but you might not get the same results as you would with Simple Green.


Can You Power Wash Composite Decking?


A power washer can be the perfect solution to clean composite decking if you have waited too long between cleanings and have a dirty buildup or have a lot of tree sap or other hard-to-remove dirt.

But proceed with caution if you decide to pull out the power washer. If it is not used properly, the high water pressure can cause irreparable damage to your composite decking.

To power wash your composite decking, follow these guidelines: 

  1. Use a pressure washer with under 3100 psi that has a fan tip attachment and a soap dispenser filled with warm, soapy water.
  2. Hold the fan tip no closer than 8-in from the surface of your composite decking. 
  3. Spray each board with soap, moving in broad, sweeping motions that follow the grain of the board.
  4. Gently scrub each deck board with a soft bristle brush.
  5. Rinse thoroughly before moving on to the next board. If you allow dirty water to dry, a grimy film will remain on the decking surface.`

What Products Should You Avoid Using on Composite Decking?

When cleaning composite decking, you NEVER want to use:

  • Bleach
  • Grease removers 
  • Other chemical products

These can damage the surface of your composite decking, break down the UV inhibitors, and cause it to bleach out over time. 


how to clean composite deck


Are You Ready To Install New Composite Decking? Contact Three Rivers Custom Decks in Portland

Is it time to install a new composite deck? 

If so, the professionals at Three Rivers Custom Decks can help. 

With our combined experience of over 25 years, we’re experts in creating beautiful, easily maintained, one-of-a-kind living spaces.

Give us a call to schedule your no-obligation consultation and start planning your dream deck today.