Big Hammer, Lowe's Deck Designer and Trex Deck Designer are free online deck design software tools. Other choices include USP Deck Designer and MoistureShield DeckLife.
MoistureShield DeckLife is a free 3-D design tool for Windows. After the design phase, the software compiles a printable list of the materials required to construct the deck. Trex Deck Designer, a similar tool, also provides lists of nearby Trex vendors and construction contractors.
Big Hammer is a free design program for decks, fences, garages and outbuildings. This product allows users to store their projects online, share them with The Home Depot associates, generate required supply lists and superimpose designs over photographs of existing property.