Plastic Decking: Is maintenance required?

Plastic Decking is a Major Investment

Plastic decking on a dock or deck is a major portion of the your investment.  It makes sense to take time to maintain it properly.  This is particularly important on marine structures vulnerable to the elements.  All plastic decking requires some yearly maintenance to remain attractive for years to come.

What causes my Plastic Decking to appear dirty?

Mold/mildew is the common term used to describe a growth on the surface of matter.  It’s caused by fungi, especially in the presence of dampness.  Under a microscope, mold has an octopus-like structure.  Its legs attach to a surface in a web-like manner.  Once mold has successfully colonized, it releases thousands of new spores over and over again. This growth makes your plastic decking appear dirty.

What makes the mold grow?

Mold needs three things to grow:

  1. Food, (Leftovers from a bird’s diet and their “droppings” provide the “menu” mold needs to thrive.)
  2. Moisture (rainwater and people walking on the dock) and
  3. Temperate weather.

When the spores are in the favorable environment described above, they will germinate.  The spores settle out of the air or are deposited by rainwater and wet feet.  As a result, they will be more prevalent on horizontal surfaces (like your dock panels).  The colonies do not migrate, but rather establish colonies and release even more spores.

Plastic decking is inorganic but nature deposits “food” and moisture in the form of rainwater. Birds deposit further nutrients and even you carry moisture, suntan lotions and dirt from the environment and deposit it on the decking.

While plastic surfaces appear sleek and impermeable, plastic decking still cannot escape the mold/mildew cycle.  Plastic decking needs to be cleaned at least once/year. This is particularly true with HDPE plastic decking (usually recycled, solid plastic boards) used as plastic decking,

How can I clean the mold and other dirt off my decking without chemicals?  

We all know that we must avoid introducing pollutants, including soaps and cleaning products into our waterways. Still, you do have an option.

With Plastic Decking it usually is not necessary to use ANY chemical cleaners.  If you must use a cleaner be sure to use natural biodegradable cleaning solutions that removes buildup without damaging the environment. 

Using a Pressure Washer on Plastic Decking makes it super easy to clean

Note – In all cases, the use of safety gloves, face masks or eye protection is highly recommended. Bare feet  and hands are very vulnerable to pressure washers and chemicals.  Serious injury can occur.

Remember- No chemicals are needed with a pressure washer on Plastic Decking.

With a pressure washer, use a “fan” nozzle with a 20 – 40 degree tip to reduce the pressure.  Never use more than 1800# of pressure. The less pressure at the sprayer head, generally the better.

Sweeping across plastic decking in either direction is very effective even without the use of chemicals.

 Hand scrubbing

Using a hand brush with natural or plastic bristles and a commercially available product like “OxiClean” is a safe way to wash the decking.  “OxiClean” breaks down to oxygen, water and soda ash so it won’t harm the environment. “OxiClean” uses oxygen ions to neutralize stains and dirt.

Many scrub brushes allow you to use a pole handle.  This way you do not have to kneel down and it will be more comfortable for you.

Do not press so hard that the bristle bend to the side as the real cleaning takes place at the ends of the bristles.  If there is a wood-like or knurled pattern in the decking surface try to follow that direction.  This allows you to get deeper into the grooves with less effort.

Get into the deck spacing as far as possible to make the decking look even better.  Before the decking dries, rinse the decking with clear water.

If the product you plan to use has oxalic acid (very corrosive) or chlorine bleach we strongly recommend that you do not use it.  It is not biodegradable and It could also get you a major fine from the DNR.

As an extra caution, check the label of any product you plan to use to see if it contains harmful ingredients like hypochlorite bleach.


Pier & Waterfront Solutions (PWS) is located in the center of Door County at 7325 St Hwy 57, south of Sturgeon Bay at the intersection of Idlewild Road.  Our staff looks forward to serving all of your waterfront needs.

Found this article helpful?  Go to “NEWS” on any page of our website for a complete list of articles meant to keep you informed on the latest product information and maintenance issues. Check out our “older entries” also.

The wide variety of articles on dock and boat lifts issues will answer many of your questions.   PWS believes that an informed consumer makes better decisions.

Call Jerry at 920-493-4404 or Email for more information.  

.  Coming Soon – “The PWS Store” on our website.