Q. What is the proper way to clean factory-made composite wood decking that has become dirty, scuffed and stained from heavy use? — B. Carlton A. Composite decks, made from ground-up wood and recycled plastic, in general require in a less degree maintenance than all-wood decks, but periodic cleaning is usually necessary to preserve the appearance. Composites also have a number of advantages over wood: They won’t rot, split or rend. But stains, mildew and dirt are common problems. B