Half of the decking in the northeastern United States is now made of synthetic materials such as plastic composites, according to a new study. Wooden decking still has a 46 percent market share in the region, but a majority of outdoor living spaces are now constructed with composite and cellular PVC boards that stand up to weather and require little maintenance. Alternative decking products, which include capped and uncapped composites, are doing best in this U.S. region, according to an industry analyst at Principia Consulting LLC, a Malvern, Pa.-based research and consulting firm. The West is next. However, in this region, alternative decking accounts for 40 percent of demand, compared with 56 percent for wood — particularly cedar — although some pockets of California prefer redwood. The market share gap widens in the Midwest, Southeast and Southwest, where wood, which also includes pressure-treated lumber and hardwoods, satisfies 59-73 percent of demand, while alternatives top out at 25-36 percent. Composite decking manufacturers are out to change that. They have been chipping away at wood sales for years with improved performance and better warranties. Now they’re tryi...