Mold: The choice for decking materials has grown considerably in the last 20 years. Many composite decking companies were started after Trex came out with the first marketable composite decking product twenty years ago. The problem with the first composite decking material was that manufacturers used saw dust combined with plastic to give a more desired natural look while providing the longevity of a plastic product. In theory this was a good idea but the problem that many consumers ran into was that over time the decking would develop spotting from mold growth. The organic natural of the sawdust contributed to this problem. Over the last 20 years, manufacturing companies have ironed out these problems by primarily moving to an all-plastic product to eliminate the spotting problem.
Strength: One of the other major problems customers ran into in Suffolk county over the early stages of composite decking manufacturing, was that the rigidity was not strong enough to span 16 inches on center. 16 inches on center is standard building code for the spacing of floor joists on all decks in Suffolk County especially in Brookhaven. As a result of this rigidity problem 2 things happened in cases of replacement decking (applies when an old deck frame is replace with new decking materials.) One, the decking planks would sag or droop in between joists to produced a wavy look to what should be a flat surface, essential ruining the deck. Two, the customer would now have to reposition the joists at 12 inches on center to support the rigidity and counter the drooping. Although this would fix the sagging problem it would add additional costs to reframe an existing structure.