Co-extruded decking is made with a plastic shell that makers say resists staining and fading better than solid composite decking. Trex says it leaves the plastic off the bottom of Transcend boards so that moisture can escape and the surface can accept adhesives. The 1-inch-by-5 1/2-inch decking is made in four colors and costs about $3 per linear foot. Matching fascia and railing components are also available. Trex, 800/289-8739,