Composites

These are plastic-wood materials that are impervious to water and will not rot. Moreover, they resist mold discoloration and are immune from the forces of shrinkage, warping, cupping, splitting and "checking" which operate on all natural wood exposed to the weather. There are many manufacturers of composites, with "Trex" being perhaps the most widely recognized. Other good manufacturers include "Timber Tech" and "Veranda" (Home Depot's brand). These materials are most frequently used for the decking surface in conjunction with pressure-treated lumber framing and either wood or metal rail systems. Most of the manufactures have their own selection of rail systems which can be used in whole or in part with other products. Other accessories include hidden fasteners which eliminate the use of visible nails or screws in the decking and leave a clean and very nice appearance.

Composites contain plastic and are therefore more subject to expansion and contraction than their wood counterparts (which typically only shrink after installation, but do not expand). For this reason, gaps must be provided between boards and at joints so as to allow for this movement. Moreover, composites can soften with heat and if not properly supported can appear "wavy". Although the manufacturers insist that 16" on center joist spacing is sufficient to counteract this tendency, Just Decks prefers to space the joists at 12" on center when using composite decking. Composites also get hot to the touch in mid-summer and can be uncomfortable to bare feet.

Perhaps due to its popularity and it superior performance to wood in weathering, the biggest disadvantage to the use of composites is their cost. The material components of a deck constructed with "Trex" typically cost about 30% more than the cost of wood – and also require more labor to install. Shopping around among brands is a disappointing exercise, as they are all priced pretty much the same.