10 Things You Should Know About Composite Decking

10 Things You Should Know About Composite Decking

By Tom Booker

If you are considering building a deck or remodeling your existing deck, you have probably been hearing a little bit about composite decking. Let me help you by sharing some insight I have developed during years of experience selling and installing composite decking.

1. Different types of decking: Although people use the label “composite” for any decking product that isn’t cut from a tree, there are actually three different classes of alternative decking products. There are true wood/plastic composites, cap-stock products, and cellular PVC products. These different types of decking have different strengths and weaknesses.

1. Wood/plastic composite. As the name implies, these products are a mixture of wood and plastic in roughly equal proportions. Composite decking is what is generally sold in the big box stores. Wood/plastic composites, or WPCs, offer the lowest performance of any of the alternative decking materials. WPCs are not maintenance free; they need to be cleaned to try to prevent mold growth, which is common among all brands of WPC products. Typically manufacturers recommend cleaning WPC decks twice each year. Most people do not clean their WPC decks, and eventually they become unsightly or they develop mold. Mold is the single biggest factor responsible for unhappy WPC owners. Mold can grow on just about anything that is outside, but it is the wood content that causes most of the problems associated with WPCs. Other issues with wood fiber are staining and moisture absorption. You can identify WPCs by looking at the surface. They tend to look somewhat fibrous, and frequently you can see the wood fibers on the surface.
2. Cap-stock materials. These products utilize a high-performance polymer or plastic shell over a composite core. The shell is referred to as a cap-stock. The process of applying the cap is called co-extrusion, so these products are also sometimes referred to as co-extruded decking. The cap-stock may cover the core on all four sides, or it may just cover the top and sides of the board. Cap-stock products perform much better than WPCs.The purpose of the cap-stock is to cover the core of the decking, while providing a high-performance finish. This keeps the cost a little lower than a cellular PVC product by allowing the use of lower cost WPC core. Most people seem to be concerned with the cap-stock separating from the core, but I have never known this to be an issue. Cap-stock products can be identified by looking at the end of the product. A clear distinction can be made between the core and the cap. Cap-stock products weigh more than PVC products, which is another way to identify which type of product you are looking at. Typically Cap-stock decking has a 25 year warranty against fading or staining.

1. Cellular PVC. These products typically do not have any wood in them at all. They are made using an expanded cell PVC. This not the same as the vinyl decking that most people think of when they hear the term PVC. Cellular PVC is a high-performance decking product. Cellular PVC decking totally removes wood from the makeup of the decking. The result is a product that is stain resistant, scratch resistant and mold resistant. Cellular PVC is also very stable, and typically requires only 1/8” spacing between boards. These products can be identified by their lack of wood fiber and their much lighter weight compared to WPCs. The one drawback to PVC boards is their strength. They are a little softer to walk on, compared to Cap-stock or composite products. If you use PVC decking I recommend a frame system that is 12” on center, rather than the standard 16” centers. Another issue that has started to come up is a problem related to Low-E glass. In some cases PVC decking has been damaged by excessive heat generated by the reflection of the sun from Low-E patio doors. Manufacturers are starting to exclude Low-E damage from their warranty coverage. This problem does not affect the Polymer coated decking products.

1. Selecting a product: Selecting a decking product can be an eye opening process. There are dozens of manufacturers. Each manufacturer has several different colors, and many offer several different lines too. There are easily over a hundred different colors and textures of decking to choose from. They don’t all perform equally either. Here, in no particular order are the general characteristics of alternative decking products:

1. Color retention: What will it look like a year from now?
2. Slip resistance: How slick is it when dry? When it is wet?
3. Mold resistance: This pertains mostly to the WPCs
4. Maintenance requirements: Does it need to be cleaned?
5. Scratch resistance: How easily will it scratch?
6. Appearance: This is still #1 on most people’s list.
7. Stain resistance: Does it stain; if so how do you remove stains?

Carefully consider all of the attributes listed above and figure out which characteristics are the most important for your lifestyle. For example, if you have young children and two large dogs, scratch resistance may be vital. If you are empty nesters, maintenance requirements and slip resistance may be more important to you. Find a deck store or a lumberyard with a good selection of products and, here is the hard part, someone that knows all about the products. Not just a person that knows about one brand, someone that really knows all of the products. Find out what products best suit your lifestyle. Take samples home. Hold them next to your house, scratch them, stain them and abuse them. See how they look afterwards. How do they clean up? When considering performance of decking products, read the warranty. It is often very different than the marketing hype.

1. Don’t let your contractor selectthe decking: Don’t misunderstand me, contractors can be an important voice when selecting decking products, just don’t let them be the only opinion you seek, and try to understand why they recommend the products they do. Contractors are creatures of habit, just like the rest of us. Some contractors start using the first product their lumberyard carried and they never even research the other products. The alternative decking world is changing so fast that products that were the best product to use just a year or two ago are now being drastically out-performed by newer products. It is really important to keep up with the latest decking products since they have changed so much in the last five years. I will let you in on another little secret: Manufacturers try hard to become the decking product of choice for your contractor. They use things like free vacations, gift cards, rewards programs and other perks to influence contractors. Sometimes your contractor is using the product because it is easy to sell or easy to install. Sometimes it is because they earn perks by selling the product. You should certainly talk to your contractor about your choices, but you should also try to understand his motivations too.

1. Measure the width: Not all alternative decking boards are the same width as wood decking. This is one way manufacturers mislead consumers, by making so called “value boards” that cost less but are much smaller. While some really are a good value, some of them are just smaller. In many cases these value boards are only 5” wide, rather than the full 5-1/2” width that is the standard in the decking world. That ½” difference equates to 9% of the width of a standard deck board. That means your value board had better be really cheap, because you will need more boards, more screws and more labor to attach them with. Many times value boards are also thinner than other decking too!

1. Color matched handrail: When you are shopping for decking for your new deck, keep in mind that not every decking has a color matched handrail. Is that a reason to avoid a particular decking color? Not at all. There are literally hundreds of rail products available today. There are composite and co-extruded handrail frames in White, Black, and any number of wood tone colors. It is not unusual to select a decking made by one manufacturer and a handrail made by another manufacturer.

1. Look at real decks: After you have narrowed your choices to one or two favorites, go look at actual decks built with those products. If you can look at a deck that is at least a year old, it will even be better. It is really difficult to tell what your deck will really look like if you are just looking at 6” long samples. By looking at a deck that has been in the elements for awhile, you can see what the deck will really look like in the real world.

1. Learn how they are installed: Although these new materials can typically be cut and drilled just like wood, installing them is still a different process than installing wood. If you are going to build your own deck, obviously you should carefully read and follow the manufacturer’s instructions. Here is what most people don’t do: I recommend reading the installation instructions even if you are going to hire professionals to build your deck. Then when you are interviewing potential contractors you will know if you are dealing with a contractor experienced with the particular product that you have selected. This will also allow you to follow along as your deck is being installed to insure it is done properly.

All newer products involve a bit of learning. Take the time to follow these steps and you will make wise choices, which will lead to a deck project that you will be happy with for years to come.

About Tom Booker

Tom has been a fixture in the Indianapolis decking market for over 20 years and spends many hours each year researching the latest trends in decking products. Tom founded Decks of Distinction in 1991. His deck installation company is a market leader in the installation of alternative decking products, and was the first company in Indianapolis to achieve top installer recognition by two of the biggest decking manufacturers. His company has received the Angie’s List Super Service Award multiple times; and has also been recognized by Indianapolis Business Journal. In 2006, frustrated by local lumberyards that only wanted to carry one or two alternative decking products, Tom and his wife Angie opened The Deck Store, a specialty lumberyard that features Indianapolis’ largest selection of decking products. Questions or comments about this report are welcomed and can be sent to .