Comparing Older Composite Decking to the Modern Product

Posted in: Deck Building Tips, Deck Building Questions, Deck Maintenance

James Moylan

Friday, April 03, 2020

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After making its appearance on the market more than 45 years ago, composite decking quickly became one of the most popular alternative decking products among builders for its durability and low maintenance.

Composite decking is made from a mix of natural wood waste and other materials, such as virgin or recycled plastic. Because of its design, it requires minimal cleaning and resists checking and splintering, but it wasn’t without its problems.


Luckily, around five years ago, a new type of composite decking emerged that is even easier to clean and maintain—capstock, or capped composite decking.

Uncapped versus Capped Composite Decking

Original uncapped composite decking is made of 100 percent composite material, with a wood flour component that makes it porous. While uncapped composite is relatively sturdy, its porous nature can cause it to soak up stains like a sponge. These stains can lead to mildew and mold within the boards if left untreated.

For certain brands of uncapped composite decking, dry rot can form if water sitting on top of the boards prevents them from breathing. To protect this older type of composite decking, regular cleaning and application of a composite surface sealant is necessary.

Capped composite decking, on the other hand, is easier to maintain. While 99 percent of this newer type of decking material is made from composite, capped decking also has an exterior skin made from a capstock material. The exterior cap provides the composite core with excellent protection from staining, scratching, and fading, making it a great long-term investment.

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Caring for Uncapped and Capped Composite Decking

Uncapped Composite:

When caring for a classic, uncapped composite decking, you should make an effort to keep your deck as dry and clean as possible. In order to avoid stains, mildew, and algae, you must clean your deck at least once or twice per year.

When cleaning, remove all leaves, debris, and organic materials, such as pollen, and wash the deck in a manufacturer-recommended cleaning product. Within one week after cleaning, you should coat the deck in a protective composite surface sealant.

Throughout the year, you can take steps to protect your uncapped composite decking material with certain precautions. You should ensure there is at least six inches of ventilation under your deck, and improve drainage to prevent standing water.

Don’t keep downspouts and splash guards around decking, and position your dryer vent so it points away from your deck. Regularly remove debris from between board gaps to allow rain to remove pollen and other debris. Try to avoid using wet mulch against the structure of the deck.

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For this type of older material, you’ll also need to pay a bit more attention to the furniture and other objects placed on the deck’s surface. Uncapped composite decking is susceptible to scratching, which means furniture, pets, and children’s toys can be a concern.

Additionally, if moisture collects beneath objects, such as hot tubs, mats, and flower pots, it may be prevented from evaporating properly. Over time, the moisture may react with the wood fiber to cause staining. While you can fight these stains with proper cleaning, the problem will continue to persist if not addressed.

Capped Composite:

While capped composite decking definitely requires less maintenance than uncapped composite, it is not completely maintenance free.  

You should regularly sweep your deck clear of leaves and other debris, and remove debris from gaps between the boards. You can clean your deck of dirt and spills with deck cleaner and regular water, spraying the mixture onto the deck and scrubbing its surface with a soft brush. These steps will keep your capstock deck looking its best for years to come.


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