In the market for decking? Chances are for those who answer “yes,” many will choose composite decking for their projects. Recent research predicts wood-plastic composite decking materials will experience double-digit demand gains through 2014, and in light of their increasing appeal, composite decking product options are more plentiful now than ever.
Among the many composite decking products being introduced are deck boards made with an outer layer or “shell” of polymer or plastic-based material surrounding a wood-plastic composite core. Referred to as cap stock composites, manufacturers are positioning these new boards as an enhanced version of traditional composite decking, stating that the extra layer makes the boards more durable and resistant to water intrusion, color fading, scratching and staining.
While this may be true for some composite products – namely those that have experienced problems with mold and mildew, excessive color loss and scratching or staining – it is not true for all. These “new and improved” claims for cap stock can mislead consumers to believe all composite decking is manufactured the same and therefore in need of additional protection. This is simply not the case.
Composite decking that is made using a total encapsulation process, wherein the wood fibers are completely surrounded and bonded in plastic, already has the all-over protection needed to make it moisture, insect and scratch and stain resistant. The durability of these composites allows them to be installed on the ground, in the ground and under the water without voiding their warranty. Some manufacturers also include pigments, stabilizers, mold and UV protectants to further enhance the product’s performance and minimize fading.
Cap stock composites use a thin layer of veneer, typically 1/16” thick, to protect an inner core that is vulnerable to mold and mildew should water infiltrate. In examining some of these new boards, it is clear that moisture can and will penetrate their core. For example, one brand of cap stock only has the outer layer on three of its four sides, leaving the bottom exposed. Another has a cap on all four sides, but when the grooves for hidden fastening systems are cut into the sides of the board, the shell is compromised. For deck boards that are installed with screws, the screws will go through the protective layer and create crevices where water can make its way in. By comparison, with boards that have fully encapsulated wood fibers, there isn’t a worry about water intrusion and how it could impact the performance or warranty.
Another concern with cap stock composites is delamination and peeling of the veneer. This has already posed problems for one popular brand of cap stock, and only time will tell whether it will become a widespread issue.
In any case, when choosing decking materials (or any material for that matter), it is very important to do your research and look beyond product claims to find what will work best for your project. New is not always better, and if there are problems with a product to begin with, they don’t necessarily go away when covered up.